fallacies arguments essay

What this handout is about

This handout discusses common logical fallacies that you may encounter in your own writing or the writing of others. The handout provides definitions, examples, and tips on avoiding these fallacies.

Most academic writing tasks require you to make an argument—that is, to present reasons for a particular claim or interpretation you are putting forward. You may have been told that you need to make your arguments more logical or stronger. And you may have worried that you simply aren’t a logical person or wondered what it means for an argument to be strong. Learning to make the best arguments you can is an ongoing process, but it isn’t impossible: “Being logical” is something anyone can do, with practice.

Each argument you make is composed of premises (this is a term for statements that express your reasons or evidence) that are arranged in the right way to support your conclusion (the main claim or interpretation you are offering). You can make your arguments stronger by:

• using good premises (ones you have good reason to believe are both true and relevant to the issue at hand),
• making sure your premises provide good support for your conclusion (and not some other conclusion, or no conclusion at all),
• checking that you have addressed the most important or relevant aspects of the issue (that is, that your premises and conclusion focus on what is really important to the issue), and
• not making claims that are so strong or sweeping that you can’t really support them.

You also need to be sure that you present all of your ideas in an orderly fashion that readers can follow. See our handouts on argument and organization for some tips that will improve your arguments.

This handout describes some ways in which arguments often fail to do the things listed above; these failings are called fallacies. If you’re having trouble developing your argument, check to see if a fallacy is part of the problem.

It is particularly easy to slip up and commit a fallacy when you have strong feelings about your topic—if a conclusion seems obvious to you, you’re more likely to just assume that it is true and to be careless with your evidence. To help you see how people commonly make this mistake, this handout uses a number of controversial political examples—arguments about subjects like abortion, gun control, the death penalty, gay marriage, euthanasia, and pornography. The purpose of this handout, though, is not to argue for any particular position on any of these issues; rather, it is to illustrate weak reasoning, which can happen in pretty much any kind of argument. Please be aware that the claims in these examples are just made-up illustrations—they haven’t been researched, and you shouldn’t use them as evidence in your own writing.

What are fallacies?

Fallacies are defects that weaken arguments. By learning to look for them in your own and others’ writing, you can strengthen your ability to evaluate the arguments you make, read, and hear. It is important to realize two things about fallacies: first, fallacious arguments are very, very common and can be quite persuasive, at least to the casual reader or listener. You can find dozens of examples of fallacious reasoning in newspapers, advertisements, and other sources. Second, it is sometimes hard to evaluate whether an argument is fallacious. An argument might be very weak, somewhat weak, somewhat strong, or very strong. An argument that has several stages or parts might have some strong sections and some weak ones. The goal of this handout, then, is not to teach you how to label arguments as fallacious or fallacy-free, but to help you look critically at your own arguments and move them away from the “weak” and toward the “strong” end of the continuum.

So what do fallacies look like?

For each fallacy listed, there is a definition or explanation, an example, and a tip on how to avoid committing the fallacy in your own arguments.

Hasty generalization

Definition: Making assumptions about a whole group or range of cases based on a sample that is inadequate (usually because it is atypical or too small). Stereotypes about people (“librarians are shy and smart,” “wealthy people are snobs,” etc.) are a common example of the principle underlying hasty generalization.

Example: “My roommate said her philosophy class was hard, and the one I’m in is hard, too. All philosophy classes must be hard!” Two people’s experiences are, in this case, not enough on which to base a conclusion.

Tip: Ask yourself what kind of “sample” you’re using: Are you relying on the opinions or experiences of just a few people, or your own experience in just a few situations? If so, consider whether you need more evidence, or perhaps a less sweeping conclusion. (Notice that in the example, the more modest conclusion “Some philosophy classes are hard for some students” would not be a hasty generalization.)

Missing the point

Definition: The premises of an argument do support a particular conclusion—but not the conclusion that the arguer actually draws.

Example: “The seriousness of a punishment should match the seriousness of the crime. Right now, the punishment for drunk driving may simply be a fine. But drunk driving is a very serious crime that can kill innocent people. So the death penalty should be the punishment for drunk driving.” The argument actually supports several conclusions—”The punishment for drunk driving should be very serious,” in particular—but it doesn’t support the claim that the death penalty, specifically, is warranted.

Tip: Separate your premises from your conclusion. Looking at the premises, ask yourself what conclusion an objective person would reach after reading them. Looking at your conclusion, ask yourself what kind of evidence would be required to support such a conclusion, and then see if you’ve actually given that evidence. Missing the point often occurs when a sweeping or extreme conclusion is being drawn, so be especially careful if you know you’re claiming something big.

Post hoc (also called false cause)

This fallacy gets its name from the Latin phrase “post hoc, ergo propter hoc,” which translates as “after this, therefore because of this.”

Definition: Assuming that because B comes after A, A caused B. Of course, sometimes one event really does cause another one that comes later—for example, if I register for a class, and my name later appears on the roll, it’s true that the first event caused the one that came later. But sometimes two events that seem related in time aren’t really related as cause and event. That is, correlation isn’t the same thing as causation.

Examples: “President Jones raised taxes, and then the rate of violent crime went up. Jones is responsible for the rise in crime.” The increase in taxes might or might not be one factor in the rising crime rates, but the argument hasn’t shown us that one caused the other.

Tip: To avoid the post hoc fallacy, the arguer would need to give us some explanation of the process by which the tax increase is supposed to have produced higher crime rates. And that’s what you should do to avoid committing this fallacy: If you say that A causes B, you should have something more to say about how A caused B than just that A came first and B came later.

Slippery slope

Definition: The arguer claims that a sort of chain reaction, usually ending in some dire consequence, will take place, but there’s really not enough evidence for that assumption. The arguer asserts that if we take even one step onto the “slippery slope,” we will end up sliding all the way to the bottom; they assume we can’t stop partway down the hill.

Example: “Animal experimentation reduces our respect for life. If we don’t respect life, we are likely to be more and more tolerant of violent acts like war and murder. Soon our society will become a battlefield in which everyone constantly fears for their lives. It will be the end of civilization. To prevent this terrible consequence, we should make animal experimentation illegal right now.” Since animal experimentation has been legal for some time and civilization has not yet ended, it seems particularly clear that this chain of events won’t necessarily take place. Even if we believe that experimenting on animals reduces respect for life, and loss of respect for life makes us more tolerant of violence, that may be the spot on the hillside at which things stop—we may not slide all the way down to the end of civilization. And so we have not yet been given sufficient reason to accept the arguer’s conclusion that we must make animal experimentation illegal right now.

Like post hoc, slippery slope can be a tricky fallacy to identify, since sometimes a chain of events really can be predicted to follow from a certain action. Here’s an example that doesn’t seem fallacious: “If I fail English 101, I won’t be able to graduate. If I don’t graduate, I probably won’t be able to get a good job, and I may very well end up doing temp work or flipping burgers for the next year.”

Tip: Check your argument for chains of consequences, where you say “if A, then B, and if B, then C,” and so forth. Make sure these chains are reasonable.

Weak analogy

Definition: Many arguments rely on an analogy between two or more objects, ideas, or situations. If the two things that are being compared aren’t really alike in the relevant respects, the analogy is a weak one, and the argument that relies on it commits the fallacy of weak analogy.

Example: “Guns are like hammers—they’re both tools with metal parts that could be used to kill someone. And yet it would be ridiculous to restrict the purchase of hammers—so restrictions on purchasing guns are equally ridiculous.” While guns and hammers do share certain features, these features (having metal parts, being tools, and being potentially useful for violence) are not the ones at stake in deciding whether to restrict guns. Rather, we restrict guns because they can easily be used to kill large numbers of people at a distance. This is a feature hammers do not share—it would be hard to kill a crowd with a hammer. Thus, the analogy is weak, and so is the argument based on it.

If you think about it, you can make an analogy of some kind between almost any two things in the world: “My paper is like a mud puddle because they both get bigger when it rains (I work more when I’m stuck inside) and they’re both kind of murky.” So the mere fact that you can draw an analogy between two things doesn’t prove much, by itself.

Arguments by analogy are often used in discussing abortion—arguers frequently compare fetuses with adult human beings, and then argue that treatment that would violate the rights of an adult human being also violates the rights of fetuses. Whether these arguments are good or not depends on the strength of the analogy: do adult humans and fetuses share the properties that give adult humans rights? If the property that matters is having a human genetic code or the potential for a life full of human experiences, adult humans and fetuses do share that property, so the argument and the analogy are strong; if the property is being self-aware, rational, or able to survive on one’s own, adult humans and fetuses don’t share it, and the analogy is weak.

Tip: Identify what properties are important to the claim you’re making, and see whether the two things you’re comparing both share those properties.

Appeal to authority

Definition: Often we add strength to our arguments by referring to respected sources or authorities and explaining their positions on the issues we’re discussing. If, however, we try to get readers to agree with us simply by impressing them with a famous name or by appealing to a supposed authority who really isn’t much of an expert, we commit the fallacy of appeal to authority.

Example: “We should abolish the death penalty. Many respected people, such as actor Guy Handsome, have publicly stated their opposition to it.” While Guy Handsome may be an authority on matters having to do with acting, there’s no particular reason why anyone should be moved by his political opinions—he is probably no more of an authority on the death penalty than the person writing the paper.

Tip: There are two easy ways to avoid committing appeal to authority: First, make sure that the authorities you cite are experts on the subject you’re discussing. Second, rather than just saying “Dr. Authority believes X, so we should believe it, too,” try to explain the reasoning or evidence that the authority used to arrive at their opinion. That way, your readers have more to go on than a person’s reputation. It also helps to choose authorities who are perceived as fairly neutral or reasonable, rather than people who will be perceived as biased.

Definition: The Latin name of this fallacy means “to the people.” There are several versions of the ad populum fallacy, but in all of them, the arguer takes advantage of the desire most people have to be liked and to fit in with others and uses that desire to try to get the audience to accept their argument. One of the most common versions is the bandwagon fallacy, in which the arguer tries to convince the audience to do or believe something because everyone else (supposedly) does.

Example: “Gay marriages are just immoral. 70% of Americans think so!” While the opinion of most Americans might be relevant in determining what laws we should have, it certainly doesn’t determine what is moral or immoral: there was a time where a substantial number of Americans were in favor of segregation, but their opinion was not evidence that segregation was moral. The arguer is trying to get us to agree with the conclusion by appealing to our desire to fit in with other Americans.

Tip: Make sure that you aren’t recommending that your readers believe your conclusion because everyone else believes it, all the cool people believe it, people will like you better if you believe it, and so forth. Keep in mind that the popular opinion is not always the right one.

Ad hominem and tu quoque

Definitions: Like the appeal to authority and ad populum fallacies, the ad hominem (“against the person”) and tu quoque (“you, too!”) fallacies focus our attention on people rather than on arguments or evidence. In both of these arguments, the conclusion is usually “You shouldn’t believe So-and-So’s argument.” The reason for not believing So-and-So is that So-and-So is either a bad person (ad hominem) or a hypocrite (tu quoque). In an ad hominem argument, the arguer attacks their opponent instead of the opponent’s argument.

Examples: “Andrea Dworkin has written several books arguing that pornography harms women. But Dworkin is just ugly and bitter, so why should we listen to her?” Dworkin’s appearance and character, which the arguer has characterized so ungenerously, have nothing to do with the strength of her argument, so using them as evidence is fallacious.

In a tu quoque argument, the arguer points out that the opponent has actually done the thing they are arguing against, and so the opponent’s argument shouldn’t be listened to. Here’s an example: imagine that your parents have explained to you why you shouldn’t smoke, and they’ve given a lot of good reasons—the damage to your health, the cost, and so forth. You reply, “I won’t accept your argument, because you used to smoke when you were my age. You did it, too!” The fact that your parents have done the thing they are condemning has no bearing on the premises they put forward in their argument (smoking harms your health and is very expensive), so your response is fallacious.

Tip: Be sure to stay focused on your opponents’ reasoning, rather than on their personal character. (The exception to this is, of course, if you are making an argument about someone’s character—if your conclusion is “President Jones is an untrustworthy person,” premises about her untrustworthy acts are relevant, not fallacious.)

Appeal to pity

Definition: The appeal to pity takes place when an arguer tries to get people to accept a conclusion by making them feel sorry for someone.

Examples: “I know the exam is graded based on performance, but you should give me an A. My cat has been sick, my car broke down, and I’ve had a cold, so it was really hard for me to study!” The conclusion here is “You should give me an A.” But the criteria for getting an A have to do with learning and applying the material from the course; the principle the arguer wants us to accept (people who have a hard week deserve A’s) is clearly unacceptable. The information the arguer has given might feel relevant and might even get the audience to consider the conclusion—but the information isn’t logically relevant, and so the argument is fallacious. Here’s another example: “It’s wrong to tax corporations—think of all the money they give to charity, and of the costs they already pay to run their businesses!”

Tip: Make sure that you aren’t simply trying to get your audience to agree with you by making them feel sorry for someone.

Appeal to ignorance

Definition: In the appeal to ignorance, the arguer basically says, “Look, there’s no conclusive evidence on the issue at hand. Therefore, you should accept my conclusion on this issue.”

Example: “People have been trying for centuries to prove that God exists. But no one has yet been able to prove it. Therefore, God does not exist.” Here’s an opposing argument that commits the same fallacy: “People have been trying for years to prove that God does not exist. But no one has yet been able to prove it. Therefore, God exists.” In each case, the arguer tries to use the lack of evidence as support for a positive claim about the truth of a conclusion. There is one situation in which doing this is not fallacious: if qualified researchers have used well-thought-out methods to search for something for a long time, they haven’t found it, and it’s the kind of thing people ought to be able to find, then the fact that they haven’t found it constitutes some evidence that it doesn’t exist.

Tip: Look closely at arguments where you point out a lack of evidence and then draw a conclusion from that lack of evidence.

Definition: One way of making our own arguments stronger is to anticipate and respond in advance to the arguments that an opponent might make. In the straw man fallacy, the arguer sets up a weak version of the opponent’s position and tries to score points by knocking it down. But just as being able to knock down a straw man (like a scarecrow) isn’t very impressive, defeating a watered-down version of your opponent’s argument isn’t very impressive either.

Example: “Feminists want to ban all pornography and punish everyone who looks at it! But such harsh measures are surely inappropriate, so the feminists are wrong: porn and its fans should be left in peace.” The feminist argument is made weak by being overstated. In fact, most feminists do not propose an outright “ban” on porn or any punishment for those who merely view it or approve of it; often, they propose some restrictions on particular things like child porn, or propose to allow people who are hurt by porn to sue publishers and producers—not viewers—for damages. So the arguer hasn’t really scored any points; they have just committed a fallacy.

Tip: Be charitable to your opponents. State their arguments as strongly, accurately, and sympathetically as possible. If you can knock down even the best version of an opponent’s argument, then you’ve really accomplished something.

Red herring

Definition: Partway through an argument, the arguer goes off on a tangent, raising a side issue that distracts the audience from what’s really at stake. Often, the arguer never returns to the original issue.

Example: “Grading this exam on a curve would be the most fair thing to do. After all, classes go more smoothly when the students and the professor are getting along well.” Let’s try our premise-conclusion outlining to see what’s wrong with this argument:

Premise: Classes go more smoothly when the students and the professor are getting along well.

Conclusion: Grading this exam on a curve would be the most fair thing to do.

When we lay it out this way, it’s pretty obvious that the arguer went off on a tangent—the fact that something helps people get along doesn’t necessarily make it more fair; fairness and justice sometimes require us to do things that cause conflict. But the audience may feel like the issue of teachers and students agreeing is important and be distracted from the fact that the arguer has not given any evidence as to why a curve would be fair.

Tip: Try laying your premises and conclusion out in an outline-like form. How many issues do you see being raised in your argument? Can you explain how each premise supports the conclusion?

False dichotomy

Definition: In false dichotomy, the arguer sets up the situation so it looks like there are only two choices. The arguer then eliminates one of the choices, so it seems that we are left with only one option: the one the arguer wanted us to pick in the first place. But often there are really many different options, not just two—and if we thought about them all, we might not be so quick to pick the one the arguer recommends.

Example: “Caldwell Hall is in bad shape. Either we tear it down and put up a new building, or we continue to risk students’ safety. Obviously we shouldn’t risk anyone’s safety, so we must tear the building down.” The argument neglects to mention the possibility that we might repair the building or find some way to protect students from the risks in question—for example, if only a few rooms are in bad shape, perhaps we shouldn’t hold classes in those rooms.

Tip: Examine your own arguments: if you’re saying that we have to choose between just two options, is that really so? Or are there other alternatives you haven’t mentioned? If there are other alternatives, don’t just ignore them—explain why they, too, should be ruled out. Although there’s no formal name for it, assuming that there are only three options, four options, etc. when really there are more is similar to false dichotomy and should also be avoided.

Begging the question

Definition: A complicated fallacy; it comes in several forms and can be harder to detect than many of the other fallacies we’ve discussed. Basically, an argument that begs the question asks the reader to simply accept the conclusion without providing real evidence; the argument either relies on a premise that says the same thing as the conclusion (which you might hear referred to as “being circular” or “circular reasoning”), or simply ignores an important (but questionable) assumption that the argument rests on. Sometimes people use the phrase “beg the question” as a sort of general criticism of arguments, to mean that an arguer hasn’t given very good reasons for a conclusion, but that’s not the meaning we’re going to discuss here.

Examples: “Active euthanasia is morally acceptable. It is a decent, ethical thing to help another human being escape suffering through death.” Let’s lay this out in premise-conclusion form:

Premise: It is a decent, ethical thing to help another human being escape suffering through death.

Conclusion: Active euthanasia is morally acceptable.

If we “translate” the premise, we’ll see that the arguer has really just said the same thing twice: “decent, ethical” means pretty much the same thing as “morally acceptable,” and “help another human being escape suffering through death” means something pretty similar to “active euthanasia.” So the premise basically says, “active euthanasia is morally acceptable,” just like the conclusion does. The arguer hasn’t yet given us any real reasons why euthanasia is acceptable; instead, they have left us asking “well, really, why do you think active euthanasia is acceptable?” Their argument “begs” (that is, evades) the real question.

Here’s a second example of begging the question, in which a dubious premise which is needed to make the argument valid is completely ignored: “Murder is morally wrong. So active euthanasia is morally wrong.” The premise that gets left out is “active euthanasia is murder.” And that is a debatable premise—again, the argument “begs” or evades the question of whether active euthanasia is murder by simply not stating the premise. The arguer is hoping we’ll just focus on the uncontroversial premise, “Murder is morally wrong,” and not notice what is being assumed.

Tip: One way to try to avoid begging the question is to write out your premises and conclusion in a short, outline-like form. See if you notice any gaps, any steps that are required to move from one premise to the next or from the premises to the conclusion. Write down the statements that would fill those gaps. If the statements are controversial and you’ve just glossed over them, you might be begging the question. Next, check to see whether any of your premises basically says the same thing as the conclusion (but in different words). If so, you’re probably begging the question. The moral of the story: you can’t just assume or use as uncontroversial evidence the very thing you’re trying to prove.

Equivocation

Definition: Equivocation is sliding between two or more different meanings of a single word or phrase that is important to the argument.

Example: “Giving money to charity is the right thing to do. So charities have a right to our money.” The equivocation here is on the word “right”: “right” can mean both something that is correct or good (as in “I got the right answers on the test”) and something to which someone has a claim (as in “everyone has a right to life”). Sometimes an arguer will deliberately, sneakily equivocate, often on words like “freedom,” “justice,” “rights,” and so forth; other times, the equivocation is a mistake or misunderstanding. Either way, it’s important that you use the main terms of your argument consistently.

Tip: Identify the most important words and phrases in your argument and ask yourself whether they could have more than one meaning. If they could, be sure you aren’t slipping and sliding between those meanings.

So how do I find fallacies in my own writing?

Here are some general tips for finding fallacies in your own arguments:

• Pretend you disagree with the conclusion you’re defending. What parts of the argument would now seem fishy to you? What parts would seem easiest to attack? Give special attention to strengthening those parts.
• List your main points; under each one, list the evidence you have for it. Seeing your claims and evidence laid out this way may make you realize that you have no good evidence for a particular claim, or it may help you look more critically at the evidence you’re using.
• Learn which types of fallacies you’re especially prone to, and be careful to check for them in your work. Some writers make lots of appeals to authority; others are more likely to rely on weak analogies or set up straw men. Read over some of your old papers to see if there’s a particular kind of fallacy you need to watch out for.
• Be aware that broad claims need more proof than narrow ones. Claims that use sweeping words like “all,” “no,” “none,” “every,” “always,” “never,” “no one,” and “everyone” are sometimes appropriate—but they require a lot more proof than less-sweeping claims that use words like “some,” “many,” “few,” “sometimes,” “usually,” and so forth.
• Double check your characterizations of others, especially your opponents, to be sure they are accurate and fair.

Can I get some practice with this?

Yes, you can. Follow this link to see a sample argument that’s full of fallacies (and then you can follow another link to get an explanation of each one). Then there’s a more well-constructed argument on the same topic.

Works consulted

We consulted these works while writing this handout. This is not a comprehensive list of resources on the handout’s topic, and we encourage you to do your own research to find additional publications. Please do not use this list as a model for the format of your own reference list, as it may not match the citation style you are using. For guidance on formatting citations, please see the UNC Libraries citation tutorial . We revise these tips periodically and welcome feedback.

Copi, Irving M., Carl Cohen, and Victor Rodych. 1998. Introduction to Logic . London: Pearson Education.

Hurley, Patrick J. 2000. A Concise Introduction to Logic , 7th ed. Belmont, CA: Wadsworth.

Lunsford, Andrea A., and John J. Ruszkiewicz. 2016. Everything’s an Argument , 7th ed. Boston: Bedford/St Martin’s.

You may reproduce it for non-commercial use if you use the entire handout and attribute the source: The Writing Center, University of North Carolina at Chapel Hill

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30 Common Logical Fallacies–A Study Starter

We help improve your debate skills with our rundown of the 30 most common logical fallacies. Not even sure what a logical fallacy is? Stick with us, we’ll cover the basics in this Study Starter.

What is a logical fallacy?

Nothing is more frustrating than debating somebody who has no idea what they’re talking about. Well, actually there is. It’s even more frustrating to debate somebody when you, yourself, have no idea what you’re talking about. So what must you do to avoid these frustrations? You can start by getting to know the most common logical fallacies.

A logical fallacy is an argument based on faulty reasoning. While fallacies come in a variety of forms, they all share the same destructive power, namely, to dismantle the validity of your entire argument. Whether you’re building a case for a position paper, engaging your classmates in a lively debate, or storing up pithy political one-liners for your next Twitter war, you need to know these common logical fallacies.

But first...

What is Logic?

Logic describes the rules and principles for making correct arguments and avoiding incorrect arguments. Logic is a key branch of philosophy, and logic students learn how to analyze and appraise arguments. In logic, certain valid rules of inference must be acknowledged and adhered to in order for an argument to be considered legitimate. Logic attempts to take us from truth to truth. In deductive logic, the truth of premises guarantees the truth of conclusions. In other types of logical inference (such as with inductive logic), the point is to make the conclusion more probable based on the truth of the premises.

Logic acknowledges the shared truths among us and guides us to uncover new truths. Logic is therefore the very fabric of meaningful debate. Without logic, human inquiry grinds to a standstill because we have no reliable way to build our knowledge based on previously uncovered truths.

What is a Logical Fallacy?

Logical fallacies are bogus modes of reasoning that can appear legitimate but in fact violate accepted rules of inference. Logical fallacies can be tricky. By masquerading as legitimate arguments, they can fool us into thinking that they are legitimate. But closer inspection reveals the critical flaw at the heart of any given logical fallacy. Such flaws are not always easily detected, especially in the heat of debate.

To confound matters, logical fallacies often have an element of truth. But the truth gets misused by faulty logic so that the desired conclusion is not properly justified. A fallacy may even reach a true conclusion, but by arriving there in the wrong way, render the conclusion unconvincing. Moreover, fallacies aren’t always driven by the desire to deceive or manipulate. Fallacies can also be rooted in bias, emotion, or misunderstanding, which can sometimes be less immediately apparent.

Why are logical fallacies so common? The answer is simple: they work! To say that logical fallacies work does not mean that they help us gain knowledge or insight into truths about the world. Rather, it means that bogus types of reasoning are often amazingly effective at getting people to believe things that they shouldn’t believe.

Lawyers, politicians, and marketers often have the keen ability to use fallacious arguments as weapons. This is rarely an accident. Unfortunately, when people want to believe something, they’ll often enlist logical fallacies to help convince themselves and others of its truth. Clear, careful, and critical thinking, therefore, requires calling out logical fallacies.

Broadly speaking, logical fallacies fall into two categories:

• Informal Fallacies, in which what the argument says, or how it says it, is flawed; and
• Formal Fallacies, in which the step-by-step progression or “form” of logical reasoning in an argument is flawed.

Why Does It Matter?

Detecting the flaws in an argument is important. Sure, identifying the flaws in an argument can be personally gratifying by helping you win a debate. But logical fallacies do a lot of damage. They threaten to undermine shared truths and advance unwarranted conclusions that rest on flawed foundations. In an age of fake news, they help fake news to proliferate.

This is your chance to spot the devil in the details. Learn how not to be deceived, because, at the risk of sounding like an alarmist, there are people out there trying to deceive you. If the purpose of debate is to illuminate the truth at the center of a discussion, logical fallacies are the smoke and shadows that obscure this truth, keeping the participants on every side of the issue from seeing clearly.

Learn these logical fallacies. Call them out when you see them. Avoid committing them yourself. This is one of the most powerful actions you can take toward preserving and advancing truth.

Not convinced? Check out our 5 Reasons You Should Take Logic Your First Year in College .

Otherwise, read on and find out which logical fallacies you’re most likely to encounter in a debate...

Common Informal Fallacies

1. ad hominem.

An abbreviated phrase meaning “to the person,” argumentum ad hominem refers to an argument which relies on an attack directed at the speaker rather than the substance of the speaker’s argument. This rhetorical strategy is often fallacious in nature, employing an approach designed to discredit the character, substance or motive of a person in lieu of deconstructing the person’s claims.

• Speaker 1: I think the idea of a moral law requires the existence of a lawgiver (i.e. God).
• Speaker 2: Of course you would say that. You’re a Christian. Why should we listen to you?
• Speaker 1: I think marijuana should be legalized. It would be better for the country if we didn’t have this drug war.
• Speaker 2: Of course you think that. You’re a pothead.
• Speaker 1: No fault divorce has proven to be detrimental to society and the family.
• Speaker 2: You didn’t seem to think that when you got divorced.
• Speaker 1: We should have single payer, government funded health care. That would be the best solution to the health care crisis in our country.
• Speaker 2: You voted for Bernie Sanders. You’re probably a communist.

Fun Fact: An ad hominem observation is not always fallacious. If the qualities attributed to the speaker are provable and relevant to the argument, an ad hominem observation may be a useful point of strategy. For instance:

• Speaker A: Private health insurance is the only way to ensure the equal distribution of resources to the public.
• Speaker B: As a former CEO of a private health insurance company who was convicted for falsifying performance reports, you can’t be trusted on this issue.

2. Appeal to Authority

The argumentum ad verecundiam , sometimes also called an “argument from authority,” describes an argument in which a speaker claims that their view is endorsed by a relevant authority figure. This claim of endorsement is presented as a sufficient argument unto itself, relieving the speaker of presenting any additional evidence to further their case. An alternate form of this fallacy is sometimes called the appeal to false or unqualified authority. In this case, the speaker might cite an individual with some measure of clout, but generally in an area outside the subject of the given argument. For instance, one might fallaciously cite a medical doctor’s opinion about politics simply because she is a very smart doctor.

• My philosophy professor believes in ghosts and goes to séances. She’s an intelligent, educated, person, so ghosts must be real, and spiritualism must be true.
• My minister says the Covid vaccine will cause genetic mutations. He has a college degree, and is a holy man, so he must be right.
• Aristotle thought women were inferior to men. Aristotle is one of the smartest men who ever lived, so he must be right about this.

Fun Fact: If both parties in a debate agree that the cited individual is a relevant authority figure, and that the facts stated in reference to this figure are accurately attributed, this appeal may not be fallacious. For this reason, there is some debate about whether or not the appeal to authority is always fallacious. However, in contexts such as science, where authority must be challenged in order for new findings to be yielded, any such appeal that comes without the support of empirical evidence should be dismissed as fallacious.

3. Appeal to Ignorance

Argumentum ad ignorantiam , also sometimes referred to as an “argument from ignorance,” occurs when a speaker presents an argument as fact simply because there is no readily available evidence to prove the contrary. This fallacy is based on a false dichotomy which posits that what we don’t know must not be true. This strategy incorrectly assumes that a lack of sufficient evidence is concrete proof that something can’t be true, a position which precludes the possibility that things may be unknown or even unknowable.

• No one has proven God exists, so He doesn’t.
• You can’t prove God doesn’t exist, so He does.
• We haven’t proven aliens didn’t create life on earth, so aliens created life on earth.
• We haven’t found life on other planets, so there’s no life on any other planet, anywhere.
• We haven’t found the ruins of Troy, so the city of Troy didn’t really exist.
• We haven’t found King David’s tomb, so King David didn’t really exist.

Fun Fact: Philosopher John Locke is sometimes credited with first coining the phrase in his 1690 text “On Reason.” Here, he explains that one way “men ordinarily use to drive others and force them to submit to their judgments, and receive their opinion in debate, is to require the adversary to admit what they allege as a proof, or to assign a better.”

4. Appeal to Pity

The argumentum ad misericordiam is a strategy in which one speaker appeals to the emotions of another by exploiting their feelings of guilt or pity. This strategy of debate seeks to validate one’s argument by playing on the sympathy or sensitivity of the other. The aim is to invoke an array of emotions that might cloud the individual’s ability to approach the argument in a rational way. It should also be noted though that the invocation of empathy is not by itself evidence that a fallacy has occurred. If we take, for instance, commercials which feature starving people in developing countries, the goal of invoking our pity is not to deceive but to connect real human emotion with a call to action. An appeal to any type of emotion is not by itself fallacious, but becomes fallacious when combined with a faulty premise.

• You should give me a promotion. I have a lot of debt and am behind on my rent.
• You can’t give me a C. I’ll lose my scholarship.
• I can’t take home a B in this course. My parents will be angry with me.
• If you don’t give me a passing grade, I won’t get accepted to medical school. That will break my grandmother’s heart.
• You should marry me. I know we’re not compatible, but I only have a year to live, and you’re my last chance.

Fun Fact: The appeal to sympathy is sometimes also referred to as the Galileo argument, so-named in honor of the Italian astronomer who lived out his final decade under house arrest for scientific claims that were deemed heretical by the Catholic Church. Presumably, what is meant by this attribution is that one’s sympathy for Galileo’s ordeal does not necessarily confer agreement with Galileo’s theories. There is no recorded instance in which the pioneering astronomer employed such a rhetorical strategy on his own behalf.

5. Appeal to Popular Opinion

The argumentum ad populum , also sometimes referred to as the common belief fallacy, refers to an instance in which a speaker asserts that something is true because many people believe it to be so. This is a fallacy in which the speaker, in lieu of providing evidence to support an argument, asserts that something is demonstrably true only because a majority of people believe it to be the case. Another form of this fallacy is called the bandwagon fallacy, so named for its implication that one should adopt a view or opinion (i.e. join the bandwagon) because so many others believe it to be so. One more variation, the appeal to elite status, suggests that you might want to share a view or position because it is held by an elite set of individuals. For instance, a well-known recruitment slogan “The few. The proud. The Marines.” both conferred elite status upon the Marines and in doing so, implied that you might want to join this select group.

• Most people think the world is flat, therefore it is flat.
• Most actors in Hollywood were against the war in Iraq, therefore the war in Iraq was wrong. (This is a subsection of ad populum: snob appeal. In this case, the opinion is outside the expertise of the people appealed to.)
• Most wealthy women wear Gucci, therefore Gucci items are beautiful, and worth the price. (Snob appeal: appeal to the elite.)
• Throughout history, most philosophers thought men were more rational than women, therefore this is true.
• Most people don’t think it’s wrong to eat meat, so it’s not.
• Most people believe in ghosts, so ghosts are real.
• Slavery is accepted by just about everyone in our society, so it’s ethical to keep slaves.

Fun Fact: If an argument is actually centered on matters of public or democratic interest, the appeal to popular opinion may be a logically sound strategy. For instance, if provable, you may argue that because 9 of 10 dentists recommend Crest toothpaste, your dentist is likely to view Crest as a superior brand of toothpaste. This would not be a fallacy.

6. Appeal to the Stone

The argumentum ad lapidem is a logical fallacy in which one speaker dismisses the argument of another as being outright absurd and patently untrue without presenting further evidence to support this dismissal. This constitutes a rhetorical effort to exploit a lack of readily available evidence to support an initial argument without necessarily presenting sufficient evidence to the contrary. By its very nature, Appeal to the Stone preempts further debate. It insulates itself against counter-argument by declining to present sufficient evidence to be rebutted. A fallacy relying on inductive reasoning, appeal to the stone is a particularly vulnerable fallacy in contexts where new evidence may eventually reveal itself.

• Speaker 1: Humans share a common ancestor with the chimpanzee.
• Speaker 2: No they don’t. Don’t be ridiculous.
• Speaker 1: Why am I ridiculous?
• Speaker 2: Evolution is absurd.
• Speaker 1: Why do you say that?
• Speaker 2: Well, it just obviously is. Look at apes, and then look at us. It’s just obviously an absurd theory.
• Speaker 1: Race is a social construct.
• Speaker 2: No, it isn’t. Don’t be absurd.
• Speaker 1: What’s absurd?
• Speaker 2: The idea that race is a social construct.
• Speaker 1: What’s absurd about it?
• Speaker 2: It just is.

Fun Fact: This fallacy is drawn from a pretty entertaining origin story. 18th century English writer Dr. Samuel Johnson and his future biographer, Scottish-born James Boswell , discussed a theory offered by Church of Ireland bishop, George Berkeley . Berkeley had claimed, through the concept of subjective idealism, that reality and material objects are dependent upon an individual’s perceptions. Both Johnson and Boswell were firm in their shared rejection of this idea. However, according to Boswell’s biography of Johnson , “I observed, that though we are satisfied his doctrine is not true, it is impossible to refute it. I never shall forget the alacrity with which Johnson answered, striking his foot with mighty force against a large stone, till he rebounded from it, ‘I refute it thus.’”

7. Causal Fallacy

Also sometimes called the fallacy of the single cause, or causal reductionism, this is a logical fallacy in which the speaker presumes that because there is a single clear explanation for an effect, that this must be the only cause. This fallacy makes the incorrect and reductive assumption that one cause precludes that possibility of multiple causes. This is a false dilemma, one which requires the speaker to ignore the possibility of other overlapping explanations and to consequently draw an unwarranted connection between a perceived cause and effect.

• I go to my front porch every morning and yell, “May no tigers enter this house!” and for 20 years, not a single tiger has entered my house. My tiger prevention strategy clearly works. .
• It’s cold on a summer day. Global warming is a hoax.
• I’ve never had the flu because I take my vitamins everyday.

Fun Fact: In essence, causal fallacy is the technical term for the exceedingly common phenomenon of “jumping to conclusions.” This is simply worth noting because it is, in many ways, a natural human behavior to which we are all predisposed at one time or another—as you await the results of a medical test; ponder the whereabouts of your missing wallet; or question the reasons somebody hasn’t texted you back even though you can clearly see that the message was delivered. In other words, uncertainty and human emotion make us all vulnerable to the occasional logical fallacy.

8. Circular Argument

Circulus in probando in Latin, this logical fallacy occurs when the premise of an argument is dependent upon acceptance of the conclusion, and the conclusion is dependent upon acceptance of the argument. In other words, both the argument and the conclusion are left wanting further proof. In circular reasoning, the originating premise lacks grounding in independent evidence, and therefore brings to the discussion no further proof to support the conclusion.

• Speaker 1: You should trust the Bible because it’s the Word of God.
• Speaker 2: How do you know it’s the Word of God?
• Speaker 1: Because God tells us it is.
• Speaker 2: Where does God tell us this?
• Speaker 1: Right here, in the Bible.
• Speaker 1: Jesus was not really crucified.
• Speaker 2: How do I know that’s true?
• Speaker 1: Because the Koran says so.
• Speaker 2: How do I know the Koran is correct?
• Speaker 1: Because the Koran is the Word of God, and everything it says is true.
• Speaker 1: Because God tells us so, here in the Koran.

Fun Fact: Circular reasoning forms the basis for the famous literary phrase “Catch-22,” which is drawn from the Joseph Heller novel of the same name. According to the satirical novel, the military maintains a policy of discharging soldiers who can demonstrate insanity. However, the military also recognizes that any sane person would desire a discharge to avoid the horrors of war. Therefore, any person seeking a discharge on the grounds of insanity is logically too sane to be eligible for discharge. This absurd contradiction is what is known, according to the author, as a “Catch-22.”

9. Equivocation

Sometimes called the Motte-and-Bailey fallacy, this is a logical fallacy in which a speaker blurs the line between two distinct positions which have some overlapping qualities. By blurring this line, it becomes possible to create an association between one position which is modest (Motte), and therefore easily defended, and a position which is likely to be more extreme (Bailey), and which is therefore more difficult to defend. By equating these positions, the speaker is presenting a false equivalence, thus forcing the other speaker to move to the defense of a position which is more difficult to defend.

• Speaker 1: Did you torture the prisoner?
• Speaker 2: No, we just held him under water for a while, and then did a mock hanging.
• According to the Supreme Court, we have a right to abortion. Therefore, it is right to have an abortion. (Legal right v. morally correct)
• A slight variation on equivocation occurs when common terms are used in an argument but with different meanings. For instance:
• Speaker 1: We are using thousands of people, who are going door to door to help us spread the word about social injustice and the need for change.
• Speaker: Well then, I can’t be a part of this because I was always been taught that it’s wrong to use people.
• Motte & Bailey Fallacy (Subset of equivocation)
• Motte (easily defensible): Different cultures and individuals have different opinions on morality.
• Bailey (more controversial/radical): Morality is completely subjective, and only a matter of opinion. There is no objective morality.

Fun Fact: The term Motte-and-Bailey was coined by philosopher Nicholas Shackell , who described the phrase as a reference to medieval castle defense systems, explaining that “A Motte and Bailey castle is a medieval system of defence in which a stone tower on a mound (the Motte) is surrounded by an area of land (the Bailey) which in turn is encompassed by some sort of a barrier such as a ditch...the Bailey, represents a philosophical doctrine or position with similar properties: desirable to its proponent but only lightly defensible. The Motte is the defensible but undesired position to which one retreats when hard pressed.”

10. Fallacy of Sunk Costs

The sunk cost fallacy proceeds from the faulty logic that the expenditure of past resources justifies the continued expenditure of resources. This fallacy contradicts rational choice theory, which holds that in economics, the only rational decisions are those which are made based on future expenses, rather than past expenses. In a broader sense, this fallacy can apply to a wide range of scenarios including the sunk cost of having remained in an unhappy relationship, having engaged in a failed war, or having dedicated years to an unsatisfying job. In each case, one might commit a fallacy by determining that past commitment to any of these scenarios necessitates a continuation of the status quo.

• Our marriage is terrible, but we’ve been together so long we might as well stay together. If we get divorced, I will have wasted 30 years.
• I hate this book. It isn’t very good. I’ve started reading it, though, so I should finish it. If I don’t finish it, I will have wasted 8 hours of my life.
• Our country has been in this war for 10 years. We’re not winning, but we continue to invest time, money, and soldiers in it because of past expenditures.

Fun Fact: A “sunk cost” is essentially the opposite of “cutting one’s losses.” For instance, in a hand of poker, a player may determine that while he is likely to lose based on his cards, he has already spent too much money on the hand to fold. This is a demonstration of the sunk cost fallacy. By contrast, the same player may recognize that while he has already spent a sum of money on this losing hand, he can still fold and hold on to his remaining funds. This is called cutting one’s losses.

11. False Dilemma

Also sometimes referred to as a “false dichotomy,” this is a fallacy in which one incorrectly places limitations on one’s possible options in a given scenario. This fallacy rests on the false premise that one is faced with a binary choice when it’s possible that multiple options are available. In essence, this occurs when one reduces the array of available options and alternatives to a simplified either-or condition.

• If you aren’t a capitalist, you must be a communist.
• Either God created the world or evolution is true.
• Speaker 1: I’m against the war.
• Speaker 2: You must hate our troops.
• You can either support our police or Black Lives Matter.

Fun Fact: The false dichotomy conflates “contraries” with “contradictories.” With contradictories, it is true that one or the other must be true. For instance, if we say somebody is alive, it means they must not be dead, and vice versa. By contrast, contraries are statements in which, at most, one such statement must be true, but in which it is also possible that neither statement is true. For instance, if we say that somebody “is not here,” we can’t definitively conclude that the person must be at home. It’s possible that the person is at home, at the supermarket, or aboard the international space station. We don’t know. From the statement, all we can conclude is that the person is not here. The false dichotomy overlooks the full array of possibilities.

12. Genetic Fallacy

Also sometimes referred to as the fallacy of origins, this is a fallacy which presumes that an argument holds no merit simply because of its source. In this instance, the history or origin of the source is used to dismiss an argument, in lieu of using actual rhetoric to address the substance of the argument.

• Speaker 1: That scientist gave a report last week on the relationship between fossil fuel and global warming. He says burning fossil fuels contributes to global warming.
• Speaker 2: He belongs to the Sierra Club and owns stock in a solar energy company. What he says cannot be true.
• Primitive people believed in gods to explain natural phenomena. We have science, and are not primitive anymore. Therefore, there is no God.
• Speaker 1: Dr. Singh says meat eating is bad for the environment.
• Speaker 2: He’s a Sikh. They don’t eat meat. Of course he would say that. He can’t be telling the truth.

Fun Fact: In one of the earliest recorded cases of usage, author Mortimer J. Adler characterized this fallacy as “the substitution of psychology for logic.”

13. Hasty Generalization

Also sometimes called a faulty generalization, this is a form of argument which arrives at a conclusion about numerous instances of a phenomenon based on evidence which is limited to only one or a few instances of said phenomenon. This denotes that one might attempt to generalize the explanation for an occurrence based on an unreliably small sample set.

• My grandmother smoked for 80 years and died at 100. Obviously, smoking isn’t harmful.
• I know five people from Kentucky. They are all racists. Therefore, Kentuckians are racist.
• My neighbor’s child was kidnapped while playing alone in her yard. My city must be a dangerous place for children.
• I know four poor families. They are lazy drug addicts. Therefore, all poor people are lazy drug addicts.

Fun Fact: The hasty or faulty generalization is the fallacy which is most at play when we apply stereotypes to full demographic groups based on anecdotal evidence or limited interaction with only select representation from that group. For instance, a person who owned a pet cat with a bad temper might make the stereotypical generalization that all cats have bad tempers.

14. Loaded Question Fallacy

A loaded question is one in which the speaker has employed rhetorical manipulation in order to limit the possible array of answers that another speaker can rationally provide. The fallacy is couched in the phrasing of such a question, which presupposes certain facts that may not be true or proven, within the content of the question. The fallacy occurs when that question is underscored by a presupposition which is not agreed upon by the person to whom the question is posed.

• Have you stopped beating your wife?
• Why did you steal my keys?
• Are you one of those stupid religious people that reject science?

Fun Fact: This form of fallacy is distinct from “begging the question,” which presumes the conclusion before the question is answered. By contrast, this strategy traps the respondent into admitting a fact which is implied by the question. Simply by virtue of answering the question, the respondent has unwittingly conceded the point.

15. Post Hoc Fallacy

In full Latin phrasing, Post hoc ergo propter hoc means “after this, therefore because of this.” Instances of this fallacy occur when one incorrectly attributes a cause and effect relationship between two phenomena in the absence of proof that one causes the other. The flaw in this strategy is that it draws a singular relationship between a premise and a conclusion without considering an array of variables that might disqualify the possibility of such a relationship.

• Every time we sacrifice virgins, it rains. Therefore, sacrificing virgins causes it to rain.
• Violence among teens has risen the last five years. Video game playing among teens has also risen the last five years. Therefore, playing video games causes teens to be violent.
• Every time I wear this necklace, I pass my exams. Therefore, wearing this necklace causes me to pass my exams.
• Every person who has ever drunk water has died. Therefore, drinking water causes death.

Fun Fact: A famous phrase often used as a counterpoint to the Post Hoc fallacy is that “correlation does not equal causation.” This denotes that just because two phenomena sometimes, or even frequently, appear in connection with one another does not mean that one causes the other.

16. Red Herring Fallacy

The red herring fallacy refers to an instance in which one speaker attempts to divert the attention of another speaker from the primary argument by offering a point which may be true, but which does not actually further the substance of a counterargument. So named for the implication that the odoriferous fish in question might “throw one off the scent” of the actual argument itself, the red herring will typically support a conclusion with a fact which does not actually provide substantive support.

• Child: This fish tastes funny. I don’t want to eat this.
• Parent: There are children starving in Africa. Eat your dinner.
• Speaker 1: I think it’s terrible that a game hunter killed Cecil the lion.
• Speaker 2: What about all the babies that are killed every day by abortion?
• Speaker 1: I really think we need to do something about the rising levels of poverty and homelessness in our country.
• Speaker 2: Why are you worried about poverty? Look how many children we abort every day.

Fun Fact: While the red herring can take the form of a logical fallacy, it is also a familiar literary and cinematic device which can be employed to misdirect the attention of the reader or viewer. This is a commonly employed tactic in mysteries, suspense thrillers, and other narratives that conclude with unexpected plot twists. For instance, in a murder mystery, the author might offer a number of clues implying that an innocent character is the killer while the actual killer hides in plain sight.

17. Slippery Slope Fallacy

Sometimes also called the continuum fallacy, this fallacy occurs when a speaker claims that a single step taken in a particular direction will inevitably lead to a series of subsequent and unintended events. This argument is used to draw a series of unforeseen and unprovable conclusions based on a single provable premise. The flaw in the slippery slope argument is that it typically forecasts an extreme range of likely subsequent events, thereby excluding the possibility that a series of more moderate events might play out instead.

• You smoke pot? If you keep doing that, you’ll be a heroin addict within two years.
• If we legalize pot, the next thing you know people will want to legalize meth and heroin.

Fun Fact: In the literary context, “slippery slope” is sometimes referred to as “the camel’s nose.” This refers to a metaphor taken from an allegory published by Geoffrey Nunberg in 1858, which tells the story of a miller who allows a camel to stick its nose through the doorway of his bedroom. Bit by bit, the camel moves other body parts into the room until he is entirely inside. Once this occurs, the camel refuses to leave.

18. Strawman Argument

The strawman fallacy occurs when a speaker appears to refute the argument of another speaker by replacing that argument with a similar but far flimsier premise. In essence, the speaker is “setting up a straw man” which can then be easily knocked down by a counterargument. The flaw in this rhetorical approach is that it fails to actually engage the original argument, in essence changing the subject so as to face a more manageable argument.

• Speaker 1: I think we should lower the age of sexual consent to 16.
• Speaker 2: 16 year olds are children. So, you think it’s OK for children to have sex? No, we shouldn’t lower the age of consent.
• Speaker 1: I think we should have single payer, universal, health care.
• Speaker 2: Communist countries tried that. We don’t want America to be a communist country. We shouldn’t have single payer health care.
• Speaker 1: I think we should have an expanded social safety net for the poor in our country.
• Speaker 2: So, you think we should just throw money at lazy people who don’t want to work and think they are entitled to be kept up by other people, right?

Fun Fact: In the U.K., the strawman argument is also sometimes referred to as “Aunt Sally,” so named for a pub game in which competitors will hurl sticks at a “skittle” balanced atop a post. The individual who knocks this precariously balanced object from its post is the winner.

19. Tu Quoque

Tu quoque , which translates to “you also,” is a fallacy in which one speaker discredits another by attacking their behavior as being inconsistent with their argument. This is a specious attack line because it seizes on certain characteristics presented by the speaker rather than on the merits of the speaker’s actual argument. Similar to ad hominem in that it resorts to a personal line of attack rather than a rhetorical argument, the primary distinction is that this personal attack is framed as having a direct connection to the argument itself. This framing is not designed to disqualify the speaker for who they are (as with ad hominem) but for how they act, and consequently, how this action appears to diverge from the premise of the speaker’s argument.

• Speaker 1: No fault divorce is really harmful to the family and the larger society.
• Speaker 2: Well, you must not really think that since you’re divorced yourself.
• Parent: I really don’t want you to smoke pot. It’s still illegal, and could get you into trouble.
• Child: Didn’t you smoke pot when you were my age? You must not think it’s a big deal.
• Speaker 1 (Democrat) : “Donald Trump is a known adulterer. It reflects badly on his character, and suggests he might not be trustworthy.”
• Speaker 2 (Republican) : “What about Bill Clinton? You didn’t seem to care when he cheated.”

Fun Fact: The high level of polarization in today’s American political discourse leads frequently to a form of the tu quoque fallacy referred to as “whataboutism.” This form of the fallacy occurs when one speaker, in lieu of responding directly to an argument, accuses another speaker of taking a hypocritical position. Take, for instance, a debate over gun control between a Republican and a Democrat:

• Democrat: Republicans support fewer regulations on gun ownership, which leads to more gun-related deaths in America.
• Republican: Well what about how Democrats support drug legalization, which leads to more drug-related deaths in America?

Common Formal Fallacies

20. affirming the consequent.

Sometimes also referred to as a converse error, this is a fallacy which occurs when one assumes that, because a conditional statement is true, then the converse of that statement must also be true. In such instances, this assumption is based on a failure to consider other possible antecedents which might also be used to offer true conditional statements. In other words, the speaker has failed to consider the full range of possible conditions for that which is consequent.

• If Hunter was human, he would be mortal. Hunter is mortal. Therefore, Hunter is a human. (Hunter may actually be my cat.)
• If it was raining outside, it would be dark. It’s dark outside, so it must be raining. (It might be 10PM.)
• If I’m psychic, I will be able to see dead people. I see dead people, therefore I’m psychic. (I might actually just be insane.)

21. Affirming the Disjunct

In the case of Affirming the Disjunct, also sometimes referred to as the false exclusionary disjunct, it is incorrectly presumed that an “or” condition excludes the possibility that “either/or” could be true. In other words, when a speaker makes a statement indicating “A or B,” the fallacy occurs when the responding speaker assumes “A, therefore, not B.” This is a fallacy of equivocation in which one assumes that because one disjunct is true, the other must be untrue.

• Gus is Christian or Gus is politically liberal.
• Gus is a Christian.
• Therefore, Gus is not politically liberal.
• Either God created the world or evolution happened.
• Evolution happened.
• Therefore, God did not create the world.

Fun Fact: Whereas Affirming the Disjunct is a logical fallacy, it should not be conflated with the disjunctive syllogism which is actually a valid form of argument. An example of an accurate disjunctive syllogism states the following:

• Bruce is American, or he is not from New Jersey.
• Bruce is not American, therefore, he is not from New Jersey.

This is a valid form of inference.

22. Appeal to Probability

The possibiliter ergo probabiliten refers to a fallacy in which one conflates possibility with probability, or in which one conflates probability with certainty. At the heart of this inductive fallacy is the error in presuming that because there is evidence that a thing is possible, one can take for granted either its probability or its certainty.

• It is possible aliens built the pyramids. Therefore, aliens built the pyramids.
• It is possible to fake the moon landing through special effects. Therefore, the moon landing was a fake using special effects.
• It’s possible to pass the class without attending regularly. Therefore, you will pass even if you don’t attend regularly.

Fun Fact: Murphy’s Law famously states that anything which can go wrong, will go wrong. This is a playful and purposeful manifestation of the Appeal to Probability Fallacy.

23. Argument From Fallacy

Also redundantly known as the fallacy fallacy, this fallacy occurs when one speaker identifies a fallacy in the argument of another and uses it in order to assert that the conclusion must be false. This fallacy incorrectly assesses that a fallacy within the argument of another necessarily precludes the possibility that the argument’s conclusion is correct.

• Speaker 1: If Hunter was human, he would be mortal. Hunter is mortal. Therefore, Hunter is a human.
• Speaker 2: You just committed the fallacy of affirming the consequent. Therefore, Hunter is not a human.
• Speaker 1: Single payer health care would be the fairest and most efficient way of giving medical care to our citizens.
• Speaker 2: You must be a communist.
• Speaker 1: You just committed the ad hominem fallacy. Therefore, I’m not a communist.

Fun Fact: This fallacy is a special form of the formal “Denying the Antecedent” fallacy. (See below.)

24. Conjunction Fallacy

In a conjunction fallacy, one assumes that a set of specific and combined conditions is likelier to be true than a single condition, without concrete evidence that either is true. In this instance, the specific set of conditions may appear to be more true because it seems to represent certain facts that seem likely to connect with the premise. However, because these conditions are more specific and because these conditions combine multiple factors which must all be true in order for the entire statement to be true, it is mathematically less likely that the statement is true than would be a simpler proposition.

Classic Example: The Linda Problem

Linda is 31 years old, single, outspoken, and very bright. She majored in philosophy. As a student she was deeply concerned with issues of discrimination and social justice, and also participated in anti-nuclear demonstrations.

Which is more probable?

• 1. Linda is a bank teller.
• 2. Linda is a bank teller and is active in the feminist movement.

If you chose #2, you have committed the conjunction fallacy. The probability of them both being true is less than or equal to the probability of only one being true. We do not know, in fact, whether either of them is true.

Fun Fact: This fallacy is sometimes called the “Linda problem,” following from the first known example supplied by psychologists Amos Tversky and Daniel Kahneman .

25. Denying the Antecedent

Sometimes also referred to as the fallacy of the inverse, denying the antecedent occurs when one deduces that because a valid premise leads to a valid conclusion, that the inverse can’t be true. In this case, the fallacy occurs when an individual presumes that because a premise and conclusion are true, the opposite of that premise must inherently mean that the conclusion is not true. In other words, one may make the valid statement that “If A, then B.” It would be a fallacy to determine that “If not A, then not B.”

• If you live in Kentucky, you love horses.
• You don’t live in Kentucky.
• Therefore, you don’t love horses.
• If you’re a hippie, you smoke weed.
• You are not a hippie.
• Therefore, you don’t smoke weed.
• If you are a communist, you believe in socialized medicine.
• You are not a communist.
• Therefore, you do not believe in socialized medicine.

Fun Fact: An argument based on denying the antecedent may actually be valid if the biconditional terminology is added to indicate “if and only if.” For instance:

• If and only if tomatoes grow on trees, then tomatoes must be fruit.
• Tomatoes don’t grow on trees. Therefore, tomatoes are not fruit.

26. Denying a Conjunct

This fallacy occurs under the condition that two premises cannot both be true at the same time. Under said condition, it is incorrect to presume that because A is not true, then B must be true. The primary flaw in this presumption is the preclusion of the possibility that neither premise is true.

• It isn’t both sunny and raining.
• It isn’t sunny.
• Therefore, it’s raining.
• Teena is not both a hippie and a communist.
• Teena is not a hippie.
• Therefore, Teena is a communist.
• I can’t be a pothead and get a job at the factory.
• I’m not a pothead.
• Therefore, I can get a job at the factory.

Fun Fact: The conclusion of the sequence need not be false in order for Denying a Conjunct to be a logical fallacy. In the example above, it is possible that the speaker could get a job at a factory. But we can’t presume that this is the case simply because the speaker isn’t a pothead. It’s possible, for instance, that regardless of whether or not the speaker smokes pot, this individual lacks the training to be hired as a factory worker.

27. Existential Fallacy

Also sometimes called existential instantiation, this fallacy occurs when one makes an argument about a category without first presenting any proof that such a category exists. In other words, it is not logical to attribute characteristics to that which doesn’t exist. Therefore, an argument which simply assumes existence while attributing such characteristics is based on an unproven premise.

• All sea creatures live in the water.
• All mermaids are sea creatures.
• Therefore, some mermaids live in the water.

(The problem here is that you may have a category of things that actually do not exist. What if there are no mermaids?)

• All cats are aliens. All aliens are dangerous. Therefore, some cats are dangerous. (What if cats didn’t exist?)

Fun Fact: “All trespassers will be prosecuted” is an oft-used existential fallacy, one which fallaciously assumes without evidence that there are trespassers even though we can’t presume the existence of trespassers based on the information provided in the statement. This fallacy can be readily corrected when one adds the condition “if such-and-such exists.” Thus, while it would not fit so elegantly on a posted sign, it would not be a fallacy to say, “If trespassers are found on my property, they will be prosecuted.”

28. Fallacy of the Undistributed Middle

Referred to in Latin as non distributio medii , this fallacy is considered a syllogistic fallacy. A syllogism is a kind of argument which occurs when two propositions are asserted to be true and, therefore, may allow one to arrive at a particular conclusion through deductive reasoning. A syllogistic fallacy occurs when there is a logical flaw in either or both propositions which prevents one from deducing this conclusion. With the undistributed middle, a fallacy occurs when a “middle term,” which is needed to reach the desired conclusion, is not included in either of two propositions.

• All students carry backpacks.—(Z is B)
• My grandfather carries a backpack.—(Y is B
• Therefore, my grandfather is a student.—(Y is Z)

A valid form of this argument would be as follows:

• All students carry backpacks.—(Y is B)
• My grandfather is a student.—(Z is Y)
• Therefore, my grandfather carries a backpack.—(Z is B)

Fun Fact: Technically, all fallacies of the Undistributed Middle are actually fallacies of either Affirming the Consequent or Denying the Antecedent. The primary distinction is that the fallacy of the undistributed middle may actually be corrected by distributing the middle, as it were. For instance, the following would be considered a fallacy:

• All billionaires are astronauts.
• Jeff Bezos is an astronaut.
• Therefore, Jeff Bezos is a billionaire.
• Everyone who is an astronaut is a billionaire.

By adding the third statement in this sequence, we have provided the “middle term” which may then be distributed to the conclusion.

29. Masked-man Fallacy

Sometimes also called the epistemic fallacy, this occurs when one assumes that because one object has a certain property, and the other does not have this property, that they cannot be the same thing. This is a fallacious assumption because it concludes that one’s knowledge of the object is equivalent to the object itself. It erroneously precludes the possibility that the object in question has some properties which are unknown to the subject.

• I know who my father is.
• I don’t know who the masked man is.
• Therefore, the masked man cannot be my father.
• I know who my husband is.
• I do not know who the robber is.
• Therefore, my husband cannot be the robber.

Fun Fact: The Masked-man Fallacy is actually an illicit use of Leibniz’s law. According to the law proposed by the German logician, if A is the same as B, then A and B share the same properties and are therefore indiscernible from one another.

30. Non-Sequitur Fallacy

Technically, a non sequitur is any invalid argument where a given premise does not logically support the given conclusion. In this way, the phrase non sequitur is practically synonymous with the word fallacy. However, in the context of a discussion on formal fallacies, a non-sequitur is a statement in which the premise has no apparent relationship with the conclusion, and therefore cannot be used to ascertain that this conclusion is true.

• I dated a lawyer. All he talked about was work. Lawyers are boring.
• My last boyfriend was really mean to me. All men are abusive.
• People like to walk on the beach. Beaches have sand. We should put sand on the floor in our living room.

Fun Fact: A non sequitur is also a commonly used device in literature and especially comedy. Here, by pairing an expected premise with an unexpected and technically fallacious conclusion, a comedian may offer an absurd and humorous observation. Take, for example, this observation from stand-up comedian Steven Wright:

• “I saw a sign: ‘Rest Area 25 Miles.’ That’s pretty big. Some people must be really tired.”

If you need to prepare for a debate, but feel clueless about how to even take notes in class, check out our guide to effective note-taking .

If you’re fascinated by the mechanics of logic, you may be naturally predisposed to the philosophy discipline. The list above really only scratches the surface on deeply intertwined subjects like logic, reason, and rhetoric. Check out these resources and rankings when you’re ready to plunge beneath this surface:

• How to Major in Philosophy
• What Can I do With a Master’s in Philosophy
• Five Reasons You Should Take Logic in Your First Year of College
• Top Influential Philosophers Today
• 25 Most Influential Philosophy Books

Find additional study resources with a look at our study guides for students at every stage of the educational journey.

Or get valuable study tips, advice on adjusting to campus life, and much more at our student resource homepage .

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Logical Fallacies

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Fallacies are common errors in reasoning that will undermine the logic of your argument. Fallacies can be either illegitimate arguments or irrelevant points, and are often identified because they lack evidence that supports their claim. Avoid these common fallacies in your own arguments and watch for them in the arguments of others.

Slippery Slope: This is a conclusion based on the premise that if A happens, then eventually through a series of small steps, through B, C,..., X, Y, Z will happen, too, basically equating A and Z. So, if we don't want Z to occur, A must not be allowed to occur either. Example:

If we ban Hummers because they are bad for the environment eventually the government will ban all cars, so we should not ban Hummers.

In this example, the author is equating banning Hummers with banning all cars, which is not the same thing.

Hasty Generalization: This is a conclusion based on insufficient or biased evidence. In other words, you are rushing to a conclusion before you have all the relevant facts. Example:

Even though it's only the first day, I can tell this is going to be a boring course.

In this example, the author is basing his evaluation of the entire course on only the first day, which is notoriously boring and full of housekeeping tasks for most courses. To make a fair and reasonable evaluation the author must attend not one but several classes, and possibly even examine the textbook, talk to the professor, or talk to others who have previously finished the course in order to have sufficient evidence to base a conclusion on.

Post hoc ergo propter hoc: This is a conclusion that assumes that if 'A' occurred after 'B' then 'B' must have caused 'A.' Example:

I drank bottled water and now I am sick, so the water must have made me sick.

In this example, the author assumes that if one event chronologically follows another the first event must have caused the second. But the illness could have been caused by the burrito the night before, a flu bug that had been working on the body for days, or a chemical spill across campus. There is no reason, without more evidence, to assume the water caused the person to be sick.

Genetic Fallacy: This conclusion is based on an argument that the origins of a person, idea, institute, or theory determine its character, nature, or worth. Example:

The Volkswagen Beetle is an evil car because it was originally designed by Hitler's army.

In this example the author is equating the character of a car with the character of the people who built the car. However, the two are not inherently related.

Begging the Claim: The conclusion that the writer should prove is validated within the claim. Example:

Filthy and polluting coal should be banned.

Arguing that coal pollutes the earth and thus should be banned would be logical. But the very conclusion that should be proved, that coal causes enough pollution to warrant banning its use, is already assumed in the claim by referring to it as "filthy and polluting."

Circular Argument: This restates the argument rather than actually proving it. Example:

George Bush is a good communicator because he speaks effectively.

In this example, the conclusion that Bush is a "good communicator" and the evidence used to prove it "he speaks effectively" are basically the same idea. Specific evidence such as using everyday language, breaking down complex problems, or illustrating his points with humorous stories would be needed to prove either half of the sentence.

Either/or: This is a conclusion that oversimplifies the argument by reducing it to only two sides or choices. Example:

We can either stop using cars or destroy the earth.

In this example, the two choices are presented as the only options, yet the author ignores a range of choices in between such as developing cleaner technology, car-sharing systems for necessities and emergencies, or better community planning to discourage daily driving.

Ad hominem: This is an attack on the character of a person rather than his or her opinions or arguments. Example:

Green Peace's strategies aren't effective because they are all dirty, lazy hippies.

In this example, the author doesn't even name particular strategies Green Peace has suggested, much less evaluate those strategies on their merits. Instead, the author attacks the characters of the individuals in the group.

Ad populum/Bandwagon Appeal: This is an appeal that presents what most people, or a group of people think, in order to persuade one to think the same way. Getting on the bandwagon is one such instance of an ad populum appeal.

If you were a true American you would support the rights of people to choose whatever vehicle they want.

In this example, the author equates being a "true American," a concept that people want to be associated with, particularly in a time of war, with allowing people to buy any vehicle they want even though there is no inherent connection between the two.

Red Herring: This is a diversionary tactic that avoids the key issues, often by avoiding opposing arguments rather than addressing them. Example:

The level of mercury in seafood may be unsafe, but what will fishers do to support their families?

In this example, the author switches the discussion away from the safety of the food and talks instead about an economic issue, the livelihood of those catching fish. While one issue may affect the other it does not mean we should ignore possible safety issues because of possible economic consequences to a few individuals.

Straw Man: This move oversimplifies an opponent's viewpoint and then attacks that hollow argument.

People who don't support the proposed state minimum wage increase hate the poor.

In this example, the author attributes the worst possible motive to an opponent's position. In reality, however, the opposition probably has more complex and sympathetic arguments to support their point. By not addressing those arguments, the author is not treating the opposition with respect or refuting their position.

Moral Equivalence: This fallacy compares minor misdeeds with major atrocities, suggesting that both are equally immoral.

That parking attendant who gave me a ticket is as bad as Hitler.

In this example, the author is comparing the relatively harmless actions of a person doing their job with the horrific actions of Hitler. This comparison is unfair and inaccurate.

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Logical Fallacies

Logical fallacies are errors in reasoning that are based on poor or faulty logic. When presented in a formal argument, they can cause you to lose your credibility as a writer, so you have to be careful of them.

Sometimes, writers will purposefully use logical fallacies to make an argument seem more persuasive or valid than it really is. In fact, the examples of fallacies on the following pages might be examples you have heard or read. While using fallacies might work in some situations, it’s irresponsible as a writer, and, chances are, an academic audience will recognize the fallacy.

However, most of the time, students accidentally use logical fallacies in their arguments, so being aware of logical fallacies and understanding what they are can help you avoid them. Plus, being aware of these fallacies can help you recognize them when you are reading and looking for source material. You wouldn’t want to use a source as evidence if the author included some faulty logic.

The following pages will explain the major types of fallacies, give you examples, and help you avoid them in your arguments.

Straw Man Fallacy

A straw man fallacy occurs when someone takes another person’s argument or point, distorts it or exaggerates it in some kind of extreme way, and then attacks the extreme distortion, as if that is really the claim the first person is making.

  Person 1:  I think pollution from humans contributes to climate change. Person 2: So, you think humans are directly responsible for extreme weather, like hurricanes, and have caused the droughts in the southwestern U.S.? If that’s the case, maybe we just need to go to the southwest and perform a “rain dance.”

The comic below gives you a little insight into what this fallacy might look like. Join Captain Logic as he works to thwart the evil fallacies of Dr. Fallacy!

In this example, you’ll notice how Dr. Fallacy completely distorted the speaker’s point. While this is an extreme example, it’s important to be careful not to fall into this kind of fallacy on a smaller scale because it’s quite easy to do. Think about times you may have even accidentally misrepresented the other side in an argument. We have to be careful to avoid even the accidental straw man fallacy!

False Dilemma Fallacy

Sometimes called the “either-or” fallacy, a false dilemma is a logical fallacy that presents only two options or sides when there are many options or sides. Essentially, a false dilemma presents a “black and white” kind of thinking when there are actually many shades of gray.

  Person 1:  You’re either for the war or against the troops. Person 2: Actually, I do not want our troops sent into a dangerous war.

The comic below gives you a little insight into what this fallacy might look like. Observe as Captain Logic saves the day from faulty logic and the evil Dr. Fallacy!

In this comic, you’ll notice that Dr. Fallacy is presenting only two options, but the first person clearly has a middle position. You have to be really careful of this kind of fallacy, as it can really turn your audience away from your position. The world is complex, and the way people think is complex. If you dismiss that, you could lose the respect and interest of your audience.

Hasty Generalization Fallacy

The hasty generalization fallacy is sometimes called the over-generalization fallacy. It is basically making a claim based on evidence that it just too small. Essentially, you can’t make a claim and say that something is true if you have only an example or two as evidence.

  Example:  Some teenagers in our community recently vandalized the park downtown. Teenagers are so irresponsible and destructive.  

You can see Dr. Fallacy in action with this type of fallacy in the comic below.

In this example, Dr. Fallacy is making a claim that all teenagers are bad based on the evidence of one incident. Even with the evidence of ten incidences, Dr. Fallacy couldn’t make the claim that all teenagers are problems.

In this instance, the fallacy seems clear, but this kind of fallacious thinking is quite common. People will make claims about all kinds of things based on one or two pieces of evidence, which is not only wrong but can be dangerous. It’s really easy to fall into this kind of thinking, but we must work to avoid it. We must hold ourselves to higher standards when we are making arguments.

Appeal to Fear Fallacy

This type of fallacy is one that, as noted in its name, plays upon people’s fear. In particular, this fallacy presents a scary future if a certain decision is made today.

  Example: 

Elizabeth Smith doesn’t understand foreign policy. If you elect Elizabeth Smith as president, we will be attacked by terrorists.  

You can see this fallacy in action in Dr. Fallacy’s campaign ad in the comic below.

Thankfully, the voters saw through Dr. Fallacy’s faulty logic. While this kind of claim seems outlandish, similar claims have been made by candidates in elections for years. Obviously, this kind of claim isn’t logical, however. No one can predict the future, but making a bold claim like this with no evidence at all is a clear logical fallacy.

Ad Hominem Fallacy

Ad hominem means “against the man,” and this type of fallacy is sometimes called name calling or the personal attack fallacy. This type of fallacy occurs when someone attacks the person instead of attacking his or her argument.

Person 1: 

I am for raising the minimum wage in our state.

She is for raising the minimum wage, but she is not smart enough to even run a business.

Check out Dr. Fallacy as he tries to get away with this type of fallacy. Thankfully, Captain Logic OWL saves the day!

In this example, Dr. Fallacy doesn’t address the issue of minimum wage and, instead, attacks the person. When we attack the person instead of tackling the issue, our audience might think we don’t understand the issue or can’t disprove our opponent’s view. It’s better to stick to the issue at hand and avoid ad hominem fallacies.

Slippery Slope Fallacy

A slippery slope fallacy occurs when someone makes a claim about a series of events that would lead to one major event, usually a bad event. In this fallacy, a person makes a claim that one event leads to another event and so on until we come to some awful conclusion. Along the way, each step or event in the faulty logic becomes more and more improbable.

Example: 

If we enact any kind of gun control laws, the next thing you know, we won’t be allowed to have any guns at all. When that happens, we won’t be able to defend ourselves against terrorist attacks, and when that happens terrorists will take over our country. Therefore, gun control laws will cause us to lose our country to terrorists.

See Dr. Fallacy in the comic below try to get away with this fallacy. Fortunately, Captain Logic saves logic and saves the day!

In this example, Dr. Fallacy is following a slippery slope to get to the point that any kind of gun regulation will lead to terrorists taking over the country. The series of events is extremely improbable, and we simply can’t make claims like this and be taken seriously in our arguments.

Of course, this example is extreme, but we do need to make sure, if we are creating a line of reasoning in terms of events leading to other events, that we aren’t falling into a slippery slope fallacy.

Bandwagon Fallacy

The bandwagon fallacy is also sometimes called the appeal to common belief or appeal to the masses because it’s all about getting people to do or think something because “everyone else is doing it” or “everything else thinks this.”

Everyone is going to get the new smart phone when it comes out this weekend. Why aren’t you?

In the comic below, Dr. Fallacy tries to persuade people using this type of fallacy.

Of course, the problem with this fallacy is not everyone is actually doing this, but there is another problem that’s important to point out. Just because a lot of people think something or do something does not mean it’s right or good to do. For example, in the 16th century, most people believed the earth was the center of the universe; of course, believing that did not make it true.

You want to be careful to avoid this fallacy, as it’s easy to fall into this kind of thinking. Think about what your parents asked you when you insisted that “everyone” was doing something that you were not getting to do: “If everyone of your friends jumped off of a cliff, would you?” It’s important to fight the urge to fall into a bandwagon fallacy.

Guilt by Association Fallacy

A guilt by association fallacy occurs when someone connects an opponent to a demonized group of people or to a bad person in order to discredit his or her argument. The idea is that the person is “guilty” by simply being similar to this “bad” group and, therefore, should not be listened to about anything.

We cannot have the educational reform that my opponent calls for because Dr. Corrupt has also mentioned this kind of educational reform.

See Dr. Fallacy use this fallacy by associating his opponent with someone named Dr. Corrupt. Clearly, this person isn’t someone to be associated with. Thankfully, Captain Logic OWL points out this flawed logic to the school board.

Here, we don’t see what issues Dr. Fallacy has with the educational reform plan, as this isn’t addressed in the fallacy. Instead of dealing with the issue, this person tries to just dismiss the point by connecting his or her opponent’s ideas with the ideas of a person who the audience wouldn’t believe.

This is problematic, of course, because we don’t deal with the issue at hand. Plus, just because “Dr. Corrupt” thinks the same thing or something similar doesn’t mean we should automatically dismiss it. We need to look more closely at the issue at hand, and it seems like the person using this fallacy doesn’t want us to.

Since Dr. Fallacy is once again thwarted by Captain Logic, this may, indeed, be his last fallacy!

Putting It All Together

It’s time to see the fallacies in action! In the videos below, you will see how one student, Mateo, engages in the process of locating sources but struggles to find sources without fallacies. Watch as he applies what he has learned about logical fallacies to his research process. Click on the first video to see Mateo’s assignment and learn about his goals. Then, click on the video that follows in order to see what fallacies Mateo encountered in his sources. When you’re finished, select the activity at the end of this page to see how well you can locate logical fallacies in sources.

Analyze This

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Writing a Paper: Avoiding Logical Fallacies

Logical fallacies are errors of reasoning—specific ways in which arguments fall apart due to faulty connection making. While logical fallacies may be used intentionally in certain forms of persuasive writing (e.g., in political speeches aimed at misleading an audience), fallacies tend to undermine the credibility of objective scholarly writing. Knowledge of how successful arguments are structured, then—as well as of the different ways they may fall apart—is a useful tool for both academic reading and writing. If you are writing an annotated bibliography or literature review, for instance, being able to recognize logical flaws in others‘ arguments may enable you to critique the validity of claims, research results, or even theories in a particular text. Along the same lines, if you are putting together your own argumentative paper (KAM, dissertation proposal, prospectus, etc.), understanding argument structure and fallacies will help you avoid errors of reasoning in your own work.

Argument Structure

The basic structure of all arguments involves three interdependent elements:

• Claim (also known as the conclusion)—What you are trying to prove. This is usually presented as your essay‘s thesis statement.
• Support (also known as the minor premise)—The evidence (facts, expert testimony, quotes, and statistics) you present to back up your claims.
• Warrant (also known as major premise)—Any assumption that is taken for granted and underlies your claim.

Consider the claim, support, and warrant for the following examples:

Example 1   Claim : The No Child Left Behind Act (NCLB, 2001) has led to an increase in high school student drop-out rates.   Support : Drop-out rates in the US have climbed by 20% since 2001.   Warrant : (The claim presupposes that) it‘s a "bad" thing for students to drop out.

Example 2   Claim : ADHD has grown by epidemic proportions in the last 10 years   Support : In 1999, the number of children diagnosed with ADHD was 2.1 million; in 2009, the number was 3.5 million.   Warrant : (The claim presupposes that) a diagnosis of ADHD is the same thing as the actual existence of ADHD; it also presupposes that ADHD is a disease.

Claims fall into three categories: claims of fact, claims of value, and claims of policy. All three types of claims occur in scholarly writing although claims of fact are probably the most common type you will encounter in research writing. Claims of fact are assertions about the existence (past, present, or future) of a particular condition or phenomenon:

Example: Japanese business owners are more inclined to use sustainable business practices than they were 20 years ago.

The above statement about Japan is one of fact; either the sustainable practices are getting more popular (fact) or they are not (fact). In contrast to claims of fact, those of value make a moral judgment about a phenomenon or condition:

Example: Unsustainable business practices are unethical.

Notice how the claim is now making a judgment call, asserting that there is greater value in the sustainable than in the unsustainable practices. Lastly, claims of policy are recommendations for actions—for things that should be done:

Example: Japanese carmakers should sign an agreement to reduce carbon emissions in manufacturing facilities by 50% by the year 2025.

The claim in this last example is that Japanese carmakers‘ current policy regarding carbon emissions needs to be changed.

For the most part, the claims you will be making in academic writing will be claims of fact. Therefore, examples presented below will highlight fallacies in this type of claim. For an argument to be effective, all three elements—claim, support, and warrant—must be logically connected.

Although there are more than two dozen types and subtypes of logical fallacies, many of these are likelier to occur in persuasive, rather than expository or research, writing. Below are the most common forms of fallacy that you may encounter in the type of expository/research writing you are apt to do at Walden:

Example: Special education students should not be required to take standardized tests because such tests are meant for nonspecial education students.

Example: Two out of three patients who were given green tea before bedtime reported sleeping more soundly. Therefore, green tea may be used to treat insomnia.

• Sweeping generalizations are related to the problem of hasty generalizations. In the former, though, the error consists in assuming that a particular conclusion drawn from a particular situation and context applies to all situations and contexts. For example, if I research a particular problem at a private performing arts high school in a rural community, I need to be careful not to assume that my findings will be generalizable to all high schools, including public high schools in an inner city setting.

Example: Professor Berger has published numerous articles in immunology. Therefore, she is an expert in complementary medicine.

Example: Drop-out rates increased the year after NCLB was passed. Therefore, NCLB is causing kids to drop out.

Example: Japanese carmakers must implement green production practices, or Japan‘s carbon footprint will hit crisis proportions by 2025.

In addition to claims of policy, false dilemma seems to be common in claims of value. For example, claims about abortion‘s morality (or immorality) presuppose an either-or about when "life" begins. Our earlier example about sustainability ("Unsustainable business practices are unethical.") similarly presupposes an either/or: business practices are either ethical or they are not, it claims, whereas a moral continuum is likelier to exist.

As you can see from the examples above, there are many ways arguments can fall apart due to faulty connection making. When trying to induce inferences from data, for instance, it‘s important not to draw conclusions too quickly or too globally; otherwise, you may end up with errors of hasty or sweeping generalization that will weaken your overall thesis. Similarly, it‘s important not to construct an either-or argument when dealing with a complex, multi-faceted issue or to assume a causal relationship when dealing with a merely temporal one; the ensuing errors—false dilemma and post hoc ergo procter hoc, respectively—may weaken argument as well. Being attentive to logical fallacies in others‘ writings will make you a more effective "critic" and writer of literature review assignments, annotated bibliographies and article critiques. Being attentive to fallacies in your own writing will help you build more compelling arguments, whether putting together a dissertation prospectus or simply writing a short discussion post on the applications of a particular theory.

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11.3 Persuasive Reasoning and Fallacies

Learning objectives.

• Define inductive, deductive, and causal reasoning.
• Evaluate the quality of inductive, deductive, and causal reasoning.
• Identify common fallacies of reasoning.

Persuasive speakers should be concerned with what strengthens and weakens an argument. Earlier we discussed the process of building an argument with claims and evidence and how warrants are the underlying justifications that connect the two. We also discussed the importance of evaluating the strength of a warrant, because strong warrants are usually more persuasive. Knowing different types of reasoning can help you put claims and evidence together in persuasive ways and help you evaluate the quality of arguments that you encounter. Further, being able to identify common fallacies of reasoning can help you be a more critical consumer of persuasive messages.

Reasoning refers to the process of making sense of things around us. In order to understand our experiences, draw conclusions from information, and present new ideas, we must use reasoning. We often reason without being aware of it, but becoming more aware of how we think can empower us to be better producers and consumers of communicative messages. The three types of reasoning we will explore are inductive, deductive, and causal.

Inductive Reasoning

Inductive reasoning reaches conclusions through the citation of examples and is the most frequently used form of logical reasoning (Walter, 1966). While introductory speakers are initially attracted to inductive reasoning because it seems easy, it can be difficult to employ well. Inductive reasoning, unlike deductive reasoning, doesn’t result in true or false conclusions. Instead, since conclusions are generalized based on observations or examples, conclusions are “more likely” or “less likely.” Despite the fact that this type of reasoning isn’t definitive, it can still be valid and persuasive.

Some arguments based on inductive reasoning will be more cogent, or convincing and relevant, than others. For example, inductive reasoning can be weak when claims are made too generally. An argument that fraternities should be abolished from campus because they contribute to underage drinking and do not uphold high academic standards could be countered by providing examples of fraternities that sponsor alcohol education programming for the campus and have members that have excelled academically (Walter, 1966). In this case, one overly general claim is countered by another general claim, and both of them have some merit. It would be more effective to present a series of facts and reasons and then share the conclusion or generalization that you have reached from them.

You can see inductive reasoning used in the following speech excerpt from President George W. Bush’s address to the nation on the evening of September 11, 2001. Notice how he lists a series of events from the day, which builds to his conclusion that the terrorist attacks failed in their attempt to shake the foundation of America.

Today, our fellow citizens, our way of life, our very freedom came under attack in a series of deliberate and deadly terrorist acts. The victims were in airplanes or in their offices: secretaries, business men and women, military and federal workers, moms and dads, friends and neighbors. Thousands of lives were suddenly ended by evil, despicable acts of terror. The pictures of airplanes flying into buildings, fires burning, huge—huge structures collapsing have filled us with disbelief, terrible sadness, and a quiet, unyielding anger. These acts of mass murder were intended to frighten our nation into chaos and retreat. But they have failed. Our country is strong. A great people has been moved to defend a great nation. Terrorist attacks can shake the foundations of our biggest buildings, but they cannot touch the foundation of America.

Using inductive reasoning, speakers reach conclusions through the citation of examples.

Claire Sambrook – UM… – CC BY-NC 2.0.

If a speaker is able to provide examples that are concrete, proxemic, and relevant to the audience, as Bush did in this example, audience members are prompted to think of additional examples that connect to their own lives. Inductive reasoning can be useful when an audience disagrees with your proposition. As you present logically connected examples as evidence that build to a conclusion, the audience may be persuaded by your evidence before they realize that the coming conclusion will counter what they previously thought. This also sets up cognitive dissonance, which is a persuasive strategy we will discuss later.

Reasoning by analogy is a type of inductive reasoning that argues that what is true in one set of circumstances will be true in another (Walter, 1966). Reasoning by analogy has been criticized and questioned by logicians, since two sets of circumstances are never exactly the same. While this is true, our goal when using reasoning by analogy in persuasive speaking is not to create absolutely certain conclusions but to cite cases and supporting evidence that can influence an audience. For example, let’s say you are trying to persuade a university to adopt an alcohol education program by citing the program’s success at other institutions. Since two universities are never exactly the same, the argument can’t be airtight. To better support this argument, you could first show that the program was actually successful using various types of supporting material such as statistics from campus offices and testimony from students and staff. Second, you could show how the cases relate by highlighting similarities in the campus setting, culture, demographics, and previous mission. Since you can’t argue that the schools are similar in all ways, choose to highlight significant similarities. Also, it’s better to acknowledge significant limitations of the analogy and provide additional supporting material to address them than it is to ignore or hide such limitations.

So how do we evaluate inductive reasoning? When inductive reasoning is used to test scientific arguments, there is rigorous testing and high standards that must be met for a conclusion to be considered valid. Inductive reasoning in persuasive speaking is employed differently. A speaker cannot cite every example that exists to build to a conclusion, so to evaluate inductive reasoning you must examine the examples that are cited in ways other than quantity. First, the examples should be sufficient, meaning that enough are cited to support the conclusion. If not, you risk committing the hasty generalization fallacy. A speaker can expect that the audience will be able to think of some examples as well, so there is no set number on how many examples is sufficient. If the audience is familiar with the topic, then fewer examples are probably sufficient, while more may be needed for unfamiliar topics. A speaker can make his or her use of reasoning by example more powerful by showing that the examples correspond to the average case, which may require additional supporting evidence in the form of statistics. Arguing that teacher salaries should be increased by providing an example of a teacher who works side jobs and pays for his or her own school supplies could be effectively supported by showing that this teacher’s salary corresponds to the national average (Walter, 1966).

Second, the examples should be typical, meaning they weren’t cherry-picked to match the point being argued. A speaker who argues to defund the National Endowment for the Arts (NEA) because the organization supports art that is “pornographic and offensive” may cite five examples of grants given for projects that caused such controversy. Failing to mention that these examples were pulled from the more than 128,000 grants issued by the NEA would be an inappropriate use of inductive reasoning since the examples aren’t sufficient or typical enough to warrant the argument. Another way to support inductive arguments is to show that the examples are a fair sample, meaning they are representative of the larger whole. Arguing that college athletes shouldn’t receive scholarships because they do not have the scholastic merit of other students and have less academic achievement could be supported by sharing several examples. But if those examples were not representative, then they are biased, and the reasoning faulty. A speaker would need to show that the athletes used in the example are representative, in terms of their race, gender, sport, and background, of the population of athletes at the university.

Deductive Reasoning

Deductive reasoning derives specifics from what is already known. It was the preferred form of reasoning used by ancient rhetoricians like Aristotle to make logical arguments (Cooper & Nothstine, 1996). A syllogism is an example of deductive reasoning that is commonly used when teaching logic. A syllogism is an example of deductive reasoning in which a conclusion is supported by major and minor premises. The conclusion of a valid argument can be deduced from the major and minor premises. A commonly used example of a syllogism is “All humans are mortal. Socrates is a human. Socrates is mortal.” In this case, the conclusion, “Socrates is mortal,” is derived from the major premise, “All humans are mortal,” and the minor premise, “Socrates is a human.” In some cases, the major and minor premises of a syllogism may be taken for granted as true. In the previous example, the major premise is presumed true because we have no knowledge of an immortal person to disprove the statement. The minor premise is presumed true because Socrates looks and acts like other individuals we know to be human. Detectives or scientists using such logic would want to test their conclusion. We could test our conclusion by stabbing Socrates to see if he dies, but since the logic of the syllogism is sound, it may be better to cut Socrates a break and deem the argument valid. Since most arguments are more sophisticated than the previous example, speakers need to support their premises with research and evidence to establish their validity before deducing their conclusion.

A syllogism can lead to incorrect conclusions if one of the premises isn’t true, as in the following example:

• All presidents have lived in the White House. (Major premise)
• George Washington was president. (Minor premise)
• George Washington lived in the White House. (Conclusion)

In the previous example, the major premise was untrue, since John Adams, our second president, was the first president to live in the White House. This causes the conclusion to be false. A syllogism can also exhibit faulty logic even if the premises are both true but are unrelated, as in the following example:

• Penguins are black and white. (Major premise)
• Some old television shows are black and white. (Minor premise)
• Some penguins are old television shows. (Conclusion)

Like in the game of Clue, real-life detectives use deductive reasoning to draw a conclusion about who committed a crime based on the known evidence.

Sleepmyf – Lego detective – CC BY-NC-ND 2.0.

Causal Reasoning

Causal reasoning argues to establish a relationship between a cause and an effect. When speakers attempt to argue for a particular course of action based on potential positive or negative consequences that may result, they are using causal reasoning. Such reasoning is evident in the following example: Eating more local foods will boost the local economy and make you healthier. The “if/then” relationship that is set up in causal reasoning can be persuasive, but the reasoning isn’t always sound. Rather than establishing a true cause-effect relationship, speakers more often set up a correlation, which means there is a relationship between two things but there are other contextual influences.

To use causal reasoning effectively and ethically, speakers should avoid claiming a direct relationship between a cause and an effect when such a connection cannot be proven. Instead of arguing that “x caused y,” it is more accurate for a speaker to say “x influenced y.” Causal thinking is often used when looking to blame something or someone, as can be seen in the following example: It’s the president’s fault that the economy hasn’t recovered more. While such a statement may garner a speaker some political capital, it is not based on solid reasoning. Economic and political processes are too complex to distill to such a simple cause-effect relationship. A speaker would need to use more solid reasoning, perhaps inductive reasoning through examples, to build up enough evidence to support that a correlation exists and a causal relationship is likely. When using causal reasoning, present evidence that shows the following: (1) the cause occurred before the effect, (2) the cause led to the effect, and (3) it is unlikely that other causes produced the effect.

Review of Types of Reasoning

• Inductive. Arguing from examples to support a conclusion; includes reasoning by analogy. Examples should be sufficient, typical, and representative to warrant a strong argument.
• Deductive. Deriving specifics from what is already known; includes syllogisms. Premises that lead to a conclusion must be true, relevant, and related for the argument to be valid.
• Causal. Argues to establish a relationship between a cause and an effect. Usually involves a correlation rather than a true causal relationship.

Fallacies of Reasoning

Fallacies are flaws within the logic or reasoning of an argument. Although we will discuss 10 common fallacies, more than 125 have been identified and named. It’s important to note that the presence of a fallacy in an argument doesn’t mean that it can’t be persuasive. In fact, many people are persuaded by fallacious arguments because they do not identify the fallacy within the argument. Fallacies are often the last effort of uninformed or ill-prepared speakers who find that they have nothing better to say. Being aware of the forms of reasoning and fallacies makes us more critical consumers of persuasive messages, which is a substantial benefit of studying persuasive speaking that affects personal, political, and professional aspects of our lives.

Hasty Generalization

The hasty generalization fallacy relates to inductive reasoning and is the result of too few examples being cited to warrant the generalization. Jumping to conclusions is tempting, especially when pressed for time, but making well-researched and supported arguments is key to being an effective and ethical speaker. Making a claim that train travel is not safe and citing two recent derailments that resulted in injury doesn’t produce a strong warrant when viewed in relation to the number of train passengers who travel safely every day.

False Analogy

The false analogy fallacy also relates to inductive reasoning and results when the situations or circumstances being compared are not similar enough. A common false analogy that people make is comparing something to putting a person on the moon: “If we can put a person on the moon, why can’t we figure out a way to make the tax code easier to understand?” This question doesn’t acknowledge the different skill sets and motivations involved in the two examples being compared.

False Cause

The false cause fallacy relates to causal reasoning and occurs when a speaker argues, with insufficient evidence, that one thing caused or causes another. When I was in high school, teachers used to say that wearing baseball caps would make us go bald when we got older. In an attempt to persuade us to not wear hats in the classroom, they were arguing, fallaciously, that wearing baseball caps is what causes baldness. When a false cause argument is made after the “effect,” it is referred to in Latin as post hoc ergo propter hoc , which means “after this, therefore because of this.” Blaming bad fortune on superstitions is a good example of faulty reasoning that tries to argue for a connection between an “effect” that has already occurred and its preceding “cause.” My bad luck is more likely attributable to poor decisions I have made or random interference than the mirror I broke while moving two years ago.

Superstitious beliefs often exemplify the false cause fallacy. Is the broken mirror really the cause of your bad luck?

Tim Sheerman-Chase – Seven Years Bad Luck – CC BY 2.0.

False Authority

The false authority fallacy results when the person making an argument doesn’t actually have the qualifications to be credible but is perceived as credible because they are respected or admired. Despite the fact that this form of argument is fallacious, it is obviously quite effective. Advertisers spend millions of dollars to get celebrities and athletes to sell us their products because of the persuasive potential these stars carry in their persona, not in their ability to argue a point. Voters might be persuaded to support a candidate because of a famous musician’s endorsement without questioning the political beliefs of either the musician or the politician to see if they match up with their own.

Parents and other sources of guidance in our lives have tried to keep us from falling for the bandwagon fallacy. When your mom responds to your argument that you should get to go to the party because everyone else is by asking, “If everyone else jumped off a bridge, would you?” she is rightfully pointing out the fallacy in your argument. In a public-speaking-related example, I have had students try to persuade their audience to buy and eat more organic foods based on their increasing popularity. In short, popular appeal and frequency of use are not strong warrants to support an argument. Just because something is popular, doesn’t mean it’s good.

False Dilemma

The false dilemma fallacy occurs when a speaker rhetorically backs his or her audience into a corner, presenting them with only two options and arguing that they must choose either one or the other. This is also known as the “either/or” fallacy. Critical thinkers know that the world can’t be simplified to black and white, good and bad, or right and wrong. Yet many people rely on such oversimplifications when making arguments. A speaker who argues that immigrants to the United States should learn English or go back to their own country doesn’t acknowledge that there are many successful immigrants who have successful lives and contribute to society without speaking English fluently. The speaker also ignores the fact that many immigrants do not have access to English language instruction or the time to take such classes because they are busy with their own jobs and families. Granted, such a rhetorical strategy does make it easier to discuss complex issues and try to force people into a decision, but it also removes gray area in the form of context that can be really important for making a decision. Be critical of speakers and messages that claim there are only two options from which to choose.

Ad hominem means “to the person” in Latin and refers to a common fallacy of attacking a person rather than an argument. Elementary school playgrounds and middle school hallways are often sites of ad hominem attacks. When one person runs out of good reasons to support their argument and retorts to the other, “Well you’re ugly!” they have resorted to a fallacious ad hominem argument. You probably aren’t surprised to know that politicians frequently rely on personal attacks, especially when they are sponsored by political action committees (PACs). The proliferation of these organizations resulted in an increase in “attack ads” during the 2012 presidential race. While all fallacious arguments detract from the quality of public communication, ad hominem arguments in particular diminish the civility of our society.

Slippery Slope

The slippery slope fallacy occurs when a person argues that one action will inevitably lead to a series of other actions. If we take one step down an icy hill it becomes difficult to get back up and you slide all the way down even though you only wanted to take one step. A slippery slope fallacy in a speech about US foreign policy might take the form of the following argument: If the United States goes to help this country in need, then we will be expected to intervene any time there’s a conflict in the world.

Red Herring

The red herring fallacy is my favorite because it has an interesting origin—and it was used in Scooby Doo ! The origin of the name of this fallacy comes from old foxhunting practices in England. When the hunters were training their dogs to stay on the trail of a fox, they would mark a trail with fox scent so the dog could practice following the scent. As a further test, they would take the smell of fish (like a red herring) and create a second trail leading in another direction. If a dog left the scent of the fox trail to follow the stronger and more noticeable scent trail left by the red herring, then the dog failed the test. The smartest and best-trained dogs weren’t distracted by the fishy trail and stayed on the path. Basically every episode of Scooby Doo involves a red herring trick—for example, when the ghost at the amusement park turns out to be a distraction created by the owner to cover up his financial problems and shady business practices. A speaker who uses the red herring fallacy makes an argument that distracts from the discussion at hand. Bringing up socialism during an argument about nationalized health care is an example of a red herring fallacy.

Appeal to Tradition

The appeal to tradition fallacy argues that something should continue because “it’s the way things have been done before.” Someone may use this type of argument when they feel threatened by a potential change. People who oppose marriage rights for gay and lesbian people often argue that the definition of marriage shouldn’t change because of its traditional meaning of a “union between one man and one woman.” Such appeals often overstate the history and prevalence of the “tradition.” Within the United States, many departures from traditional views of marriage have led to changes that we accept as normal today. Within the past one hundred years we have seen law changes that took away men’s rights to beat their wives and make decisions for them. And it wasn’t until 1993 that every state made marital rape a crime, which changed the millennia-old “tradition” that women were obligated to have sex with their husbandsf (Coontz, 2006). Many people are resistant to or anxious about change, which is understandable, but this doesn’t form the basis of a good argument.

Review of Fallacies

• Hasty generalization. Inductive reasoning fallacy that occurs when too few examples are cited to warrant a conclusion.
• False analogy. Inductive reasoning fallacy that occurs when situations or circumstances being compared are not similar enough.
• False cause. Causal reasoning fallacy that occurs when a speaker argues with insufficient evidence that one thing caused/causes another.
• False authority. Fallacy that occurs when a person making an argument doesn’t have the knowledge or qualifications to be credible but is perceived as credible because they are respected or admired.
• Bandwagon. Fallacy that relies on arguing for a course of action or belief because it is commonly done or held.
• False dilemma. Fallacy that occurs when a speaker presents an audience only two options and argues they must choose one or the other.
• Ad hominem. Fallacy that occurs when a speaker attacks another person rather than his or her argument.
• Slippery slope. Fallacy that occurs when a person argues that one action will inevitably lead to a series of other actions.
• Red herring. Fallacy that occurs when a speaker poses an argument that is meant to distract from the argument at hand.
• Appeal to tradition. Fallacy that results when a speaker argues that something should continue because “it’s the way things have been done before.”

Key Takeaways

We use reasoning to make sense of the world around us and draw conclusions. Three types of reasoning are inductive, deductive, and causal.

• Inductive reasoning refers to arguments that persuade by citing examples that build to a conclusion. Examples should be sufficient, typical, and representative to warrant a strong argument. Reasoning by analogy argues that what is true in one set of circumstances will be true in another, and is an example of inductive reasoning.
• Deductive reasoning refers to arguments that derive specifics from what is already known and includes syllogisms. Premises that lead to the conclusion must be true and relevant for the argument to be valid.
• Causal reasoning refers to arguments that establish a relationship between a cause and an effect and usually involves a correlation rather than a true causal relationship.
• Fallacies refer to flaws within the logic or reasoning of an argument. Ten fallacies of reasoning discussed in this chapter are hasty generalization, false analogy, false cause, false authority, false dilemma, ad hominem, slippery slope, red herring, and appeal to tradition.
• Identify examples of inductive, deductive, and causal reasoning in the sample persuasive speech on education in prisons included in Section 4.3 “Nonverbal Communication Competence” .
• People often use fallacies in arguments, usually without knowing it. Being able to identify fallacies is an important critical thinking skill. Find a letter to the editor in a paper or online and see if you can identify any of the ten fallacies discussed in this chapter.
• Of the ten fallacies discussed in the chapter, which do you think is the most unethical and why?

Coontz, S., “Traditional Marriage Has Changed a Lot,” Seattle Post Intelligencer , February 23, 2006, accessed March 6, 2012, http://www.seattlepi.com/default/article/Traditional-marriage-has-changed-a-lot-1196563.php .

Cooper, M. D., and William L. Nothstine, Power Persuasion: Moving an Ancient Art into the Media Age (Greenwood, IN: Educational Video Group, 1996), 27.

Walter, O. M., Speaking to Inform and Persuade (New York: Macmillan, 1966), 58.

Communication in the Real World Copyright © 2016 by University of Minnesota is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License , except where otherwise noted.

How to Support an Argument and Avoid Logical Fallacies

What is an argument.

Every day we are presented with dozens of arguments that purport to be factual. Every day we must evaluate these statements and decide what we think about them—not only whether we agree with them or not, but also whether we think they are true. As you read this, you might take a minute to stop and think about how many such messages and statements you have already encountered today and how you thought about them.

Parts of an Argument

There are three basic parts to any argument, that is, three basic parts to any statement that is intended to persuade or prove something.

• Conclusion : This may or may not come at the end and is the author’s main idea
• Evidence : This is whatever the author or speaker uses to support the conclusion. (Below you will read about the various kinds of evidence, how to use them, and how to recognize when they are being misused.)
• Assumption (or Warrant) : This is rarely stated explicitly in the argument, but is absolutely central. The assumption is what holds the argument together and determines how the author or speaker looks at the evidence and comes to the conclusion.

Evaluating Arguments by Identifying the Assumption

The following examples illustrate how you can identify an author’s assumption by looking at the other parts (evidence and conclusion) of their argument:

• Evidence : Arbuthnot looks out his window and sees that it is snowing heavily.
• Conclusion : Winter is a difficult and dangerous time of year.

What is Arbuthnot’s assumption in making this statement? Although we cannot know with absolute certainty, we can make a well-informed guess that his assumption has to do with how dangerous snow is. For instance, Arbuthnot may be afraid of driving in snow or afraid that he will fall while shoveling snow. Whether you agree with his conclusion or not, you can at least see his assumption at work. Here is another example:

• Evidence : Montgomery looks out his window and sees that it is snowing heavily.
• Conclusion : Winter is great! I look forward to it every year.

What is Montgomery’s assumption? Well, without more to go on we cannot say absolutely, but we can safely guess that it must be something that includes an enjoyment of snow. For instance, Montgomery might love downhill skiing, snowboarding, and snowmobile-riding or making snow angels. Do you see how this works?

So, in order to evaluate the worth of any argument, you must consider what the author’s assumption might be. In the examples, Montgomery and Arbuthnot have exactly the same evidence, and yet have come to very different conclusions. What makes the difference? They started from different assumptions. Thus, when you are evaluating an argument presented to you, ask yourself what the author’s assumption might be. Then, consider whether you think that is a sound assumption. For instance, here is an argument:

We are the best because we sell the most!

Have you ever heard this argument before? What is the assumption here? It is that quantity (of sales) equals quality (of product)? Do you think that is a sound assumption? Do you agree with it?

Tools for an Effective Argument

In addition to operating on a sound assumption, to argue convincingly the author must present evidence and analysis that support the conclusion.

Five common tools in an effective argument:

• Expert opinions

Correct and Incorrect Use of Logic and Evidence

Evidence from experts.

The opinions of experts (also called authorities) can be invaluable. These are people who have some special knowledge on the subject, and their support lends believability to the author’s point. For instance, in a paper on why smoking is unhealthy, the U.S. Surgeon General and the chairs of either the American Lung Association or American Cancer Association would be strong authorities. Their authority comes from their professional experience. People become authorities for different reasons. They may have academic or professional training and experience, or they may also be people with extensive personal experience. Another authority on this topic might be a life-long smoker who now has extensive health problems.

However, using authorities may pose some dangers: The person may not be an authority in the right area. For example, “My lawyer told me about a great way to make my car run more fuel efficiently.” Advertising is notorious for using false authorities. For instance, Michael Jordan might be a good authority on the best basketball shoes, but does he really know more about underwear than anyone else? The classic example: “I may not be a doctor, but I play one on TV, so I know this is the best flu relief out there.”

Additionally, the topic may be hotly debated within the field—experts may disagree. When citing an authority, ask yourself not only if the person is truly an authority, but if they are in the area you are discussing. Also, note whether peers in the field generally accept what the authority says as true.

Evidence from Facts

Facts are proven to be true. For example, Helen Keller died on June 1, 1968. Support for this comes from many sources, one of which is her obituary in the The New York Times : http://www.nytimes.com/learning/general/onthisday/bday/0627.html

Facts are reliable sources of evidence. The problem comes in distinguishing fact from opinion. Opinions may look like facts, but they cannot be proven. For example, “The death penalty is wrong.” While one could gather evidence to support this opinion, one could also gather evidence against it. Ultimately, whether something is “wrong” or “right” is opinion.

Additionally, people may disguise opinion as fact by saying things like “The truth of the matter is . . .” or “It is a fact that . . .” but that does not mean what follows is fact. As a reader and writer, you need to evaluate what follows to determine if it is truly fact or opinion.

Evidence from Examples

Examples can be useful forms of evidence. In fact, in conversation, we often ask people to “give me an example.” For instance, your child comes home and says, “My teacher is not fair and does not like me.” You would most likely ask your child to give you some examples to support this claim. What could your child say back to you that would support the claim about the teacher?

Here are some possibilities: “They never call on me,” “They laugh when I give the wrong answer,” and so on. These examples clearly support your child’s claim, so they would be considered useful. What if, instead, your child said, “They wear the same outfit every day” or “They drink too much coffee”? Unless the teacher wears a shirt that says “I dislike Bobby” on it every day, you would say, “What does that have to do with how much they like you?” These examples do not support the claim. This example is an exaggeration, of course, but oftentimes people will use examples as evidence even though they really do not support their claims. You have to be on the alert for this as a writer and reader.

Using Logic

Authors use logic to build one known or proven fact upon another, leading the reader to agree that a certain point is true. For example, consider the case of Frank who has six cats. To prevent having even more cats, all Frank’s cats are female. Now consider his cat Zoe. What is Zoe’s sex? We know that all Frank’s cats are female, and we know Zoe belongs to Frank, so we can conclude that Zoe is a female. That is logic.

Logical arguments fall into two categories: induction and deduction. Deduction takes a generally known fact and uses it to argue for a more specific point. The example above of Frank and his cats is an example of deductive reasoning. Deduction is common. Induction, on the other hand, takes a specific case (or cases) and uses it to argue for a bigger generalization.

For example, it was hot today. It was hot yesterday, the day before, and the day before that. A logical conclusion is that it is summer. Induction is widely used in science. Scientists studying a particular species may notice that several individuals of that species exhibit a particular behavior.

They may then induce that all members of that species exhibit the behavior, even though they have not examined every individual member.

Induction is used less frequently because it can be faulty. For example, it was hot today. It was hot yesterday, the day before, and the day before that. What if it is not summer, but actually just a record-breaking October? Induction becomes more valid as the instances used to support the general conclusion become more specific.

Common Logical Fallacies

As seen above, even logical reasoning can result in incorrect conclusions. These are called logical fallacies. Several are common enough to have their own names and are described below.

Anecdotal Fallacy

Anecdotal fallacy, also called a hasty generalization or jumping to conclusions, is an inductive fallacy that occurs when one instance supports a general claim that is not true. For example, “I had a female boss once. She was demanding and unfair. Female bosses are the worst.” The speaker is using one example, the one female boss he or she had, to argue that all female bosses are horrid. Obviously—and your own personal experience may speak to this—they are not all bad.

Mistaking Time for Cause and Effect

Just because one thing happened prior to another does not mean the first caused the second, yet frequently people will argue just that. For instance, “The repair person was here this morning, and now my keys are missing. They must have stolen them.” The speaker could have just as easily misplaced them. Maybe their child grabbed them by accident. Just because A (the repair person at the house) happened before B (the loss of the keys) does not mean A caused B.

False Authority

When we trust authorities, we need to make sure they are authorities on the subject about which they are speaking. The speaker could tell you a great deal about acting, but not about your health.

Slippery Slope

Slippery-slope arguments are based on the idea that if one thing happens, then another thing will, then another, and another. Think of this as the “domino effect.” The problem is that while the first thing might lead to the next, there is no proof that any of the other things will happen. For example, “If I let my brother borrow this CD, then he will borrow my books, then he will want to borrow my clothes, and pretty soon, he will take over my bedroom!” (Children, among others, use this argument a lot.) While a brother allowed to borrow a CD might then ask to borrow a book, the guarantee that this will lead to room invasion is nonexistent. This logical fallacy should seem familiar—it is frequently used in political discussions on gun control and abortion.

Either-Or Dilemmas (A False Dichotomy)

“It is your choice—get a gym membership or be alone forever.” Are these really the only two options? Are there ways other than a gym membership to find that special someone? Of course there is. Either-or dilemmas, however, hide that fact by claiming only two options exist. Whenever you hear only two options, be suspicious. Other options likely exist.

Circular Reasoning

Circular reasoning, also called begging the question, happens when an assumption is used to prove the same assumption is true. In other words, the conclusion simply puts the assumption in other words. For example, “Jennifer Anniston is more popular than Courtney Cox-Arquette because more people like her.” Being popular and being liked are basically the same thing, so all this says is “She is more popular because she is more popular,” which is not saying much.

This literally means “against the person.” When a claim is rejected based simply on the person making it and not on the evidence the person has put forth, it is an ad hominem logical fallacy. The person, not the claim, is attacked. Why is this a logical fallacy? Because the claim the person is making is never attacked—only the person is. This personal attack is then used, falsely, to undermine the claim. Since the claim was never attacked, logically it has not been undermined, yet the attacker claims that it has. Here is an example:

• Meg : I hope the NFL is able to keep its eligibility requirements. According to ESPN, there are 1200 agents registered with the NFL. Over half have no clients. If the eligibility requirements are dropped, these agents are going to be filling high school football stadiums, scouting for new prospects, and convincing a lot of kids to forgo college in hopes of an NFL career. The bottom line is most won’t make it, and what will they have? No education, no job, and no hopes.
• Alan : You’re just a girl—what do you know about football?

For more examples of logical fallacies used in argument, refer to the Purdue Global Writing Center resource on Hasty Generalizations and Other Logical Fallacies .

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Two competing conceptions of fallacies are that they are false but popular beliefs and that they are deceptively bad arguments. These we may distinguish as the belief and argument conceptions of fallacies. Academic writers who have given the most attention to the subject of fallacies insist on, or at least prefer, the argument conception of fallacies, but the belief conception is prevalent in popular and non-scholarly discourse. As we shall see, there are yet other conceptions of what fallacies are, but the present inquiry focuses on the argument conception of fallacies.

Being able to detect and avoid fallacies has been viewed as a supplement to criteria of good reasoning. The knowledge of fallacies is needed to arm us against the most enticing missteps we might take with arguments—so thought not only Aristotle but also the early nineteenth century logicians Richard Whately and John Stuart Mill. But as the course of logical theory from the late nineteenth-century forward turned more and more to axiomatic systems and formal languages, the study of reasoning and natural language argumentation received much less attention, and hence developments in the study of fallacies almost came to a standstill. Until well past the middle of the twentieth century, discussions of fallacies were for the most part relegated to introductory level textbooks. It was only when philosophers realized the ill fit between formal logic, on the one hand, and natural language reasoning and argumentation, on the other, that the interest in fallacies has returned. Since the 1970s the utility of knowing about fallacies has been acknowledged (Johnson and Blair 1993), and the way in which fallacies are incorporated into theories of argumentation has been taken as a sign of a theory’s level of adequacy (Biro and Siegel 2007, van Eemeren 2010).

In modern fallacy studies it is common to distinguish formal and informal fallacies. Formal fallacies are those readily seen to be instances of identifiable invalid logical forms such as undistributed middle and denying the antecedent. Although many of the informal fallacies are also invalid arguments, it is generally thought to be more profitable, from the points of view of both recognition and understanding, to bring their weaknesses to light through analyses that do not involve appeal to formal languages. For this reason it has become the practice to eschew the symbolic language of formal logic in the analysis of these fallacies; hence the term ‘informal fallacy’ has gained wide currency. In the following essay, which is in four parts, it is what is considered the informal-fallacy literature that will be reviewed. Part 1 is an introduction to the core fallacies as brought to us by the tradition of the textbooks. Part 2 reviews the history of the development of the conceptions of fallacies as it is found from Aristotle to Copi. Part 3 surveys some of the most recent innovative research on fallacies, and Part 4 considers some of the current research topics in fallacy theory.

1. The core fallacies

2.1 aristotle, 2.3 arnauld and nicole, 2.6 bentham, 2.7 whately, 3.1 renewed interest, 3.2 doubts about fallacies, 3.3 the informal logic approach to fallacies, 3.4 the formal approach to informal fallacies, 3.5 the epistemic approach to fallacies, 3.6 dialectical/dialogical approaches to fallacies, 4.1 the nature of fallacies, 4.2 the appearance condition, 4.3 teaching, other internet resources, related entries.

Irving Copi’s 1961 Introduction to Logic gives a brief explanation of eighteen informal fallacies. Although there is some variation in competing textbooks, Copi’s selection captured what for many was the traditional central, core fallacies. [ 1 ] In the main, these fallacies spring from two fountainheads: Aristotle’s Sophistical Refutations and John Locke’s An Essay Concerning Human Understanding (1690). By way of introduction, a brief review of the core fallacies, especially as they appear in introductory level textbooks, will be given. Only very general definitions and illustrations of the fallacies can be given. This proviso is necessary first, because, the definitions (or identity conditions) of each of the fallacies is often a matter of contention and so no complete or final definition can be given in an introductory survey; secondly, some researchers wish that only plausible and realistic instances of each fallacy be used for illustration. This also is not possible at this stage. The advantage of the stock examples of fallacies is that they are designed to highlight what the mistake associated with each kind of fallacy is supposed to be. Additional details about some of the fallacies are found in Sections 2 and 3. As an initial working definition of the subject matter, we may take a fallacy to be an argument that seems to be better than it really is.

1. The fallacy of equivocation is an argument which exploits the ambiguity of a term or phrase which has occurred at least twice in an argument, such that on the first occurrence it has one meaning and on the second another meaning. A familiar example is:

The end of life is death. Happiness is the end of life. So, death is happiness.

‘The end of life’ first means ceasing to live, then it means purpose. That the same set of words is used twice conceals the fact that the two distinct meanings undermine the continuity of the reasoning, resulting in a non-sequitur .

2. The fallacy of amphiboly is, like the fallacy of equivocation, a fallacy of ambiguity; but here the ambiguity is due to indeterminate syntactic structure. In the argument:

The police were told to stop drinking on campus after midnight. So, now they are able to respond to emergencies much better than before

there are several interpretations that can be given to the premise because it is grammatically ambiguous. On one reading it can be taken to mean that it is the police who have been drinking and are now to stop it; this makes for a plausible argument. On another reading what is meant is that the police were told to stop others (e.g., students) from drinking after midnight. If that is the sense in which the premise is intended, then the argument can be said to be a fallacy because despite initial appearances, it affords no support for the conclusion.

3 & 4. The fallacies of composition and division occur when the properties of parts and composites are mistakenly thought to be transferable from one to the other. Consider the two sentences:

• Every member of the investigative team was an excellent researcher.
• It was an excellent investigative team.

Here it is ‘excellence’ that is the property in question. The fallacy of composition is the inference from (a) to (b) but it need not hold if members of the team cannot work cooperatively with each other. The reverse inference from (b) to (a)—the fallacy of division—may also fail if some essential members of the team have a supportive or administrative role rather than a research role.

5. The fallacy of begging the question ( petitio principii ) can occur in a number of ways. One of them is nicely illustrated with Whately’s (1875 III §13) example: “to allow everyman an unbounded freedom of speech must always be, on the whole, advantageous to the State; for it is highly conducive to the interest of the Community, that each individual should enjoy a liberty perfectly unlimited, of expressing his sentiments.” This argument begs the question because the premise and conclusion are the very same proposition, albeit expressed in different words. It is a disguised instance of repetition which gives no reason for its apparent conclusion.

Another version of begging the question can occur in contexts of argumentation where there are unsettled questions about key terms. Suppose, for example, that everyone agrees that to murder someone requires doing something that is wrong, but not everyone agrees that capital punishment is a form of ‘murder’; some think it is justified killing. Then, should an arguer gives this argument:

Capital punishment requires an act of murdering human beings. So, capital punishment is wrong.

one could say that this is question-begging because in this context of argumentation, the arguer is smuggling in as settled a question that remains open. That is, if the premise is accepted without further justification, the arguer is assuming the answer to a controversial question without argument.

Neither of these versions of begging the question are faulted for their invalidity, so they are not charged with being non-sequitors like most of the core fallacies; they are, however, attempted proofs that do not transparently display their weakness. This consideration, plus its ancient lineage back to Aristotle, might explain begging the question’s persistent inclusion among fallacies. But, given our allegiance to the modern conception of logic as being solely concerned with the following-from relation, forms of begging the question should be thought of as epistemic rather than logical fallacies.

Some versions of begging the question are more involved and are called circular reasoning. They include more than one inference. Descartes illustrated this kind of fallacy with the example of our belief in the Bible being justified because it is the word of God, and our belief in God’s existence being justified because it is written in the Bible. [ 2 ] The two propositions lead back and forth to each other, in a circle, each having only the support of the other.

6. The fallacy known as complex question or many questions is usually explained as a fallacy associated with questioning. For example, in a context where a Yes or No answer must be given, the question, “Are you still a member of the Ku Klux Klan?” is a fallacy because either response implies that one has in the past been a member of the Klan, a proposition that may not have been established as true. Some say that this kind of mistake is not really a fallacy because to ask a question is not to make an argument.

7. There are a number of fallacies associated with causation, the most frequently discussed is post hoc ergo propter hoc , (after this, therefore because of this). This fallacy ascribes a causal relationship between two states or events on the basis of temporal succession. For example,

Unemployment decreased in the fourth quarter because the government eliminated the gasoline tax in the second quarter.

The decrease in unemployment that took place after the elimination of the tax may have been due to other causes; perhaps new industrial machinery or increased international demand for products. Other fallacies involve confusing the cause and the effect, and overlooking the possibility that two events are not directly related to each other but are both the effect of a third factor, a common cause. These fallacies are perhaps better understood as faults of explanation than faults of arguments.

8. The fallacy of ignoratio elenchi , or irrelevant conclusion, is indicative of misdirection in argumentation rather than a weak inference. The claim that Calgary is the fastest growing city in Canada, for example, is not defeated by a sound argument showing that it is not the biggest city in Canada. A variation of ignoratio elenchi , known under the name of the straw man fallacy, occurs when an opponent’s point of view is distorted in order to make it easier to refute. For example, in opposition to a proponent’s view that (a) industrialization is the cause of global warming, an opponent might substitute the proposition that (b) all ills that beset mankind are due to industrialization and then, having easily shown that (b) is false, leave the impression that (a), too, is false. Two things went wrong: the proponent does not hold (b), and even if she did, the falsity of (b) does not imply the falsity of (a).

There are a number of common fallacies that begin with the Latin prefix ‘ ad ’ (‘to’ or ‘toward’) and the most common of these will be described next.

9. The ad verecundiam fallacy concerns appeals to authority or expertise. Fundamentally, the fallacy involves accepting as evidence for a proposition the pronouncement of someone who is taken to be an authority but is not really an authority. This can happen when non-experts parade as experts in fields in which they have no special competence—when, for example, celebrities endorse commercial products or social movements. Similarly, when there is controversy, and authorities are divided, it is an error to base one’s view on the authority of just some of them. (See also 2.4 below.)

10. The fallacy ad populum is similar to the ad verecundiam , the difference being that the source appealed to is popular opinion, or common knowledge, rather than a specified authority. So, for example:

These days everyone (except you) has a car and knows how to drive; So, you too should have a car and know how to drive.

Often in arguments like this the premises aren’t true, but even if they are generally true they may provide only scant support for their conclusions because that something is widely practised or believed is not compelling evidence that it is true or that it should be done. There are few subjects on which the general public can be said to hold authoritative opinions. Another version of the ad populum fallacy is known as “playing to the gallery” in which a speaker seeks acceptance for his view by arousing relevant prejudices and emotions in his audience in lieu of presenting it with good evidence.

11. The ad baculum fallacy is one of the most controversial because it is hard to see that it is a fallacy or even that it involves bad reasoning. Ad baculum means “appeal to the stick” and is generally taken to involve a threat of injury of harm to the person addressed. So, for example,

If you don’t join our demonstration against the expansion of the park, we will evict you from your apartment; So, you should join our demonstration against the expansion of the park.

Such threats do give us reasons to act and, unpleasant as the interlocutor may be, there seems to be no fallacy here. In labour disputes, and perhaps in international relations, using threats such as going on strike, or cutting off trade routes, are not normally considered fallacies, even though they do involve intimidation and the threat of harm. However, if we change to doxastic considerations, then the argument that you should believe that candidate \(X\) is the one best suited for public office because if you do not believe this you will be evicted from your apartment, certainly is a good instance of irrelevant evidence.

12. The fallacy ad misericordiam is a companion to the ad baculum fallacy: it occurs not when threats are out of place but when appeals for sympathy or pity are mistakenly thought to be evidence. To what extent our sympathy for others should influence our actions depends on many factors, including circumstances and our ethical views. However, sympathy alone is generally not evidence for believing any proposition. Hence,

You should believe that he is not guilty of embezzling those paintings; think of how much his family suffered during the Depression.

Ad misericordiam arguments, like ad baculum arguments, have their natural home in practical reasoning; it is when they are used in theoretical (doxastic) argumentation that the possibility of fallacy is more likely.

13. The ad hominem fallacy involves bringing negative aspects of an arguer, or their situation, to bear on the view they are advancing. There are three commonly recognized versions of the fallacy. The abusive ad hominem fallacy involves saying that someone’s view should not be accepted because they have some unfavorable property.

Thompson’s proposal for the wetlands may safely be rejected because last year she was arrested for hunting without a license.

The hunter Thompson, although she broke the law, may nevertheless have a very good plan for the wetlands.

Another, more subtle version of the fallacy is the circumstantial ad hominem in which, given the circumstances in which the arguer finds him or herself, it is alleged that their position is supported by self-interest rather than by good evidence. Hence, the scientific studies produced by industrialists to show that the levels of pollution at their factories are within the law may be undeservedly rejected because they are thought to be self-serving. Yet it is possible that the studies are sound: just because what someone says is in their self-interest, does not mean it should be rejected.

The third version of the ad hominem fallacy is the tu quoque . It involves not accepting a view or a recommendation because the espouser him- or herself does not follow it. Thus, if our neighbor advises us to exercise regularly and we reject her advice on the basis that she does not exercise regularly, we commit the tu quoque fallacy: the value of advice is not wholly dependent on the integrity of the advisor.

We may finish our survey of the core fallacies by considering just two more.

14. The fallacy of faulty analogy occurs when analogies are used as arguments or explanations and the similarities between the two things compared are too remote to support the conclusion.

If a child gets a new toy he or she will want to play with it; So, if a nation gets new weapons, it will want to use them.

In this example (due to Churchill 1986, 349) there is a great difference between using (playing with) toys and using (discharging) weapons. The former is done for amusement, the latter is done to inflict harm on others. Playing with toys is a benign activity that requires little justification; using weapons against others nations is something that is usually only done after extensive deliberation and as a last resort. Hence, there is too much of a difference between using toys and using weapons to conclude that a nation, if it acquires weapons, will want to use them as readily as children will want to play with their toys.

15. The fallacy of the slippery slope generally takes the form that from a given starting point one can by a series of incremental inferences arrive at an undesirable conclusion, and because of this unwanted result, the initial starting point should be rejected. The kinds of inferences involved in the step-by-step argument can be causal, as in:

You have decided not to go to college; If you don’t go to college, you won’t get a degree; If you don’t get a degree, you won’t get a good job; If you don’t get a good job, you won’t be able to enjoy life; But you should be able to enjoy life; So, you should go to college.

The weakness in this argument, the reason why it is a fallacy, lies in the second and third causal claims. The series of small steps that lead from an acceptable starting point to an unacceptable conclusion may also depend on vague terms rather than causal relations. Lack of clear boundaries is what enables the puzzling slippery slope arguments known as “the beard” and “the heap.” In the former, a person with a full beard eventually becomes beardless as hairs of the beard are removed one-by-one; but because the term ‘beard’ is vague it is unclear at which intermediate point we are to say that the man is now beardless. Hence, at each step in the argument until the final hair-plucking, we should continue to conclude that the man is bearded. In the second case, because ‘heap’ is vague, it is unclear at what point piling scattered stones together makes them a heap of stones: if it is not a heap to begin with, adding one more stone will not make it a heap, etc. In both these cases apparently good reasoning leads to a false conclusion.

Many other fallacies have been named and discussed, some of them quite different from the ones mentioned above, others interesting and novel variations of the above. Some of these will be mentioned in the review of historical and contemporary sources that follows.

2. History of Fallacy Theory

The history of the study of fallacies begins with Aristotle’s work, On Sophistical Refutations . It is among his earlier writings and the work appears to be a continuation of the Topics , his treatise on dialectical argumentation. Although his most extensive and theoretically detailed discussion of fallacies is in the Sophistical Refutations , Aristotle also discusses fallacies in the Prior Analytics and On Rhetoric . Here we will concentrate on summarizing the account given in the Sophistical Refutations . In that work, four things are worth noting: (a) the different conceptions of fallacy; (b) the basic concepts used to explain fallacies; (c) Aristotle’s explanation of why fallacies can be deceptive; and (d) his enumeration and classification of fallacies.

2.1.1 Definitions

At the beginning of Topics (I, i), Aristotle distinguishes several kinds of deductions (syllogisms). They are distinguished first on the basis of the status of their premises. (1) Those that begin from true and primary premises, or are owed to such, are demonstrations. (2) Those which have dialectical premises—propositions acceptable to most people, or to the wise—are dialectical deductions. (3) Deductions that start from premises which only appear to be dialectical, are fallacious deductions because of their starting points, as are (4) those “deductions” that do have dialectical premises but do not really necessitate their conclusions. Other fallacies mentioned and associated with demonstrations are (5) those which only appear to start from what is true and primary ( Top ., I, i 101a5). What this classification leaves out are (6) the arguments that do start from true and primary premises but then fail to necessitate their conclusions; two of these, begging the question and non-cause are discussed in Prior Analytics (II, 16, 17). It is the “fallacious deductions” characterized in (4), however, that come closest to the focus of the Sophistical Refutations . Nevertheless, in many of the examples given what stands out is that the premises are given as answers in dialogue and are to be maintained by the answerer, not necessarily that they are dialectical in the sense of being common opinions. This variation on dialectical deductions Aristotle calls examination arguments ( SR 2 165b4).

2.1.2 The basic concepts

There are three closely related concepts needed to understand sophistical refutations. By a deduction (a syllogism [ 3 ] ) Aristotle meant an argument which satisfies three conditions: it “is based on certain statements made in such a way as necessarily to cause the assertion of things other than those statements and as a result of those statements” ( SR 1 165a1–2). Thus an argument may fail to be a syllogism in three different ways. The premises may fail to necessitate the conclusion, the conclusion may be the same as one of the premises, and the conclusion may not be caused by (grounded in) the premises. The concept of a proof underlying Sophistical Refutations is similar to what is demanded of demonstrative knowledge in Posterior Analytics (I ii 71b20), viz., that the premises must be “true, primary, immediate, better known than, prior to, and causative of the conclusion,” except that the first three conditions do not apply to deductions in which the premises are obtained through questioning. A refutation , Aristotle says, is “a proof of the contradictory” ( SR 6, 168a37)—a proof of the proposition which is the contradictory of the thesis maintained by the answerer. In a context of someone, S , maintaining a thesis, T , a dialectical refutation will consist in asking questions of S , and then taking S ’s answers and using them as the premises of a proof via a deduction of not-T : this will be a refutation of T relative to the answerer ( SR 8 170a13). The concept of contradiction can be found in Categories : it is those contraries which are related such that “one opposite needs must be true, while the other must always be false” (13b2–3). A refutation will be sophistical if either the proof is only an apparent proof or the contradiction is only an apparent contradiction. Either way, according to Aristotle, there is a fallacy. Hence, the opening of his treatise: “Let us now treat of sophistical refutations, that is, arguments which appear to be refutations but are really fallacies and not refutations” ( SR 1 164a20).

2.1.3 The appearance condition

Aristotle observed that “reasoning and refutation are sometimes real and sometimes not, but appear to be real owing to men’s inexperience; for the inexperienced are like those who view things from a distance” ( SR , 1 164b25). The ideas here are first that there are arguments that appear to be better than they really are; and second that people inexperienced in arguments may mistake the appearance for the reality and thus be taken in by a bad argument or refutation. Apparent refutations are primarily explained in terms of apparent deductions: thus, with one exception, Aristotle’s fallacies are in the main a catalogue of bad deductions that appear to be good deductions. The exception is ignoratio elenchi in which, in one of its guises, the deduction contains no fallacy but the conclusion proved only appears to contradict the answerer’s thesis.

Aristotle devotes considerable space to explaining how the appearance condition may arise. At the outset he mentions the argument that turns upon names ( SR 1 165a6), saying that it is the most prolific and usual explanation: because there are more things than names, some names will have to denote more than one thing, thereby creating the possibility of ambiguous terms and expressions. That the ambiguous use of a term goes unnoticed allows the illusion that an argument is a real deduction. The explanation of how the false appearance can arise is in the similarity of words or expressions with different meanings, and the smallness of differences in meaning between some expressions ( SR 7 169a23–169b17).

2.1.4 List and classification

Aristotle discusses thirteen ways in which refutations can be sophistical and divides them into two groups. The first group, introduced in Chapter 4 of On Sophistical Refutations , includes those Aristotle considers dependent on language ( in dictione ), and the second group, introduced in Chapter 5, includes those characterized as not being dependent on language ( extra dictionem ). Chapter 6 reviews all the fallacies from the view point of failed refutations, and Chapter 7 explains how the appearance of correctness is made possible for each fallacy. Chapters 19–30 advise answerers on how to avoid being taken in by sophistical refutations.

The fallacies dependent on language are equivocation, amphiboly, combination of words, division of words, accent and form of expression. Of these the first two have survived pretty much as Aristotle thought of them. Equivocation results from the exploitation of a term’s ambiguity and amphiboly comes about through indefinite grammatical structure. The one has to do with semantical ambiguity, the other with syntactical ambiguity. However, the way that Aristotle thought of the combination and division fallacies differs significantly from modern treatments of composition and division. Aristotle’s fallacies are the combinations and divisions of words which alter meanings, e.g., “walk while sitting” vs. “walk-while-sitting,” (i.e., to have the ability to walk while seated vs. being able to walk and sit at the same time). For division, Aristotle gives the example of the number 5: it is 2 and 3. But 2 is even and 3 is odd, so 5 is even and odd. Double meaning is also possible with those words whose meanings depend on how they are pronounced, this is the fallacy of accent, but there were no accents in written Greek in Aristotle’s day; accordingly, this fallacy would be more likely in written work. What Aristotle had in mind is something similar to the double meanings that can be given to ‘unionized’ and ‘invalid’ depending on how they are pronounced. Finally, the fallacy that Aristotle calls form of expression exploits the kind of ambiguity made possible by what we have come to call category mistakes, in this case, fitting words to the wrong categories. Aristotle’s example is the word ‘flourishing’ which may appear to be a verb because of its ‘ing’ ending (as in ‘cutting’ or ‘running’) and so belongs to the category of actions, whereas it really belongs in the category of quality. Category confusion was, for Aristotle, the key cause of metaphysical mistakes.

There are seven kinds of sophistical refutation that can occur in the category of refutations not dependent on language: accident, secundum quid , consequent, non-cause, begging the question, ignoratio elenchi and many questions.

The fallacy of accident is the most elusive of the fallacies on Aristotle’s list. It turns on his distinction between two kinds of predication, unique properties and accidents ( Top . I 5). The fallacy is defined as occurring when “it is claimed that some attribute belongs similarly to the thing and to its accident” ( SR 5 166b28). What belongs to a thing are its unique properties which are counterpredicable (Smith 1997, 60), i.e., if \(A\) is an attribute of \(B\), \(B\) is an attribute of \(A\). However, attributes that are accidents are not counterpredicates and to treat them as such is false reasoning, and can lead to paradoxical results; for example, if it is a property of triangles that they are equal to two right angles, and a triangle is accidentally a first principle, it does not follow that all first principles have two right angles (see Schreiber 2001, ch. 7).

Aristotle considers the fallacy of consequent to be a special case of the fallacy of accident, observing that consequence is not convertible, i.e., “if \(A\) is, \(B\) necessarily is, men also fancy that, if \(B\) is, \(A\) necessarily is” ( SR 5 169b3). One of Aristotle’s examples is that it does not follow that “a man who is hot must be in a fever because a man who is in a fever is hot” ( SR 5 169b19). This fallacy is sometimes claimed as being an early statement of the formal fallacy of affirming the consequent.

The fallacy of secundum quid comes about from failing to appreciate the distinction between using words absolutely and using them with qualification. Spruce trees, for example, are green with respect to their foliage (they are ‘green’ with qualification); it would be a mistake to infer that they are green absolutely because they have brown trunks and branches. It is because the difference between using words absolutely and with qualification can be minute that this fallacy is possible, thinks Aristotle.

Begging the question is explained as asking for the answer (the proposition) which one is supposed to prove, in order to avoid having to make a proof of it. Some subtlety is needed to bring about this fallacy such as a clever use of synonymy or an intermixing of particular and universal propositions ( Top . VIII, 13). If the fallacy succeeds the result is that there will be no deduction: begging the question and non-cause are directly prohibited by the second and third conditions respectively of being a deduction ( SR 6 168b23).

The fallacy of non-cause occurs in contexts of ad impossibile arguments when one of the assumed premises is superfluous for deducing the conclusion. The superfluous premise will then not be a factor in deducing the conclusion and it will be a mistake to infer that it is false since it is a non-cause of the impossibility. This is not the same fallacy mentioned by Aristotle in the Rhetoric (II 24) which is more akin to a fallacy of empirical causation and is better called false cause (see Woods and Hansen 2001).

Aristotle’s fallacy of many questions occurs when two questions are asked as if they are one proposition. A proposition is “a single predication about a single subject” ( SR 6 169a8). Thus with a single answer to two questions one has two premises for a refutation , and one of them may turn out to be idle, thus invalidating the deduction (it becomes a non-cause fallacy). Also possible is that extra-linguistic part-whole mistakes may happen when, for example, given that something is partly good and partly not-good, the double question is asked whether it is all good or all not-good? Either answer will lead to a contradiction (see Schreiber 2000, 156–59). Despite its name, this fallacy consists in the ensuing deduction, not in the question which merely triggers the fallacy.

On one interpretation ignoratio elenchi is considered to be Aristotle’s thirteenth fallacy, in which an otherwise successful deduction fails to end with the required contradictory of the answerer’s thesis. Seen this way, ignoratio elenchi is unlike all the other fallacies in that it is not an argument that fails to meet one of the criteria of a good deduction, but a genuine deduction that turns out to be irrelevant to the point at issue. On another reading, ignoratio elenchi is not a separate fallacy but an alternative to the language dependent / language independent way of classifying the other twelve fallacies: they all fail to meet, in one way or another, the requirements of a sound refutation.

[A] refutation is a contradiction of one and the same predicate, not of a name but of a thing, and not of a synonymous name but of an identical name, based on the given premises and following necessarily from them (the original point at issue not being included) in the same respect, manner and time. ( SR 5 167a23–27)

Each of the other twelve fallacies is analysed as failing to meet one of the conditions in this definition of refutation ( SR 6). Aristotle seems to favour this second reading, but it leaves the problem of explaining how refutations that miss their mark can seem like successful refutations. A possible explanation is that a failure to contradict a given thesis can be made explicit by adding the negation of the thesis as a last step of the deduction, thereby insuring the contradiction of the thesis, but only at the cost (by the last step) of introducing one of the other twelve fallacies in the deduction.

2.1.5 Different interpretations

I have given only the briefest possible explanation of Aristotle’s fallacies. To really understand them a much longer engagement with the original text and the secondary sources is necessary. The second chapter of Hamblin’s (1970) book is a useful introduction to the Sophistical Refutations , and a defence of the dialectical nature of the fallacies. Hamblin thinks that a dialectical framework is indispensable for an understanding of Aristotle’s fallacies and that part of the poverty of contemporary accounts of fallacies is due to a failure to understand their assumed dialectical setting. This approach to the fallacies is continued in contemporary research by some argumentation theorists, most notably Douglas Walton (1995) who also follows Aristotle in recognizing a number of different kinds of dialogues in which argumentation can occur; Frans van Eemeren and Rob Grootendorst (2004) who combine dialectical and pragmatic insights with an ideal model of a critical discussion; and Jaakko Hintikka who analyses the Aristotelian fallacies as mistakes in question-dialogues (Hintikka 1987; Bachman 1995.) According to Hintikka (1997) it is an outright mistake to think of Aristotle’s fallacies primarily as mistaken inferences, either deductive or inductive. A non-dialogue oriented interpretation of Aristotle fallacies is found in Woods and Hansen (1997 and 2001) who argue that the fallacies (apparent deductions) are basic to apparent refutations, and that Aristotle’s interest in the fallacies extended beyond dialectical contests, as is shown by his interest in them in the Prior Analytics and the Rhetoric (II 24). What gives unity to Aristotle’s different fallacies on this view is not a dialogue structure but rather their dependence on the concepts of deduction and proof. The most thorough recent study of these questions is in Schreiber (2003), who emphasizes Aristotle’s concern with resolving (exposing) fallacies and argues that it is Aristotelian epistemology and metaphysics that is needed for a full understanding of the fallacies in the Sophistical Refutations .

Francis Bacon deserves a brief mention in the history of fallacy theory, not because he made any direct contribution to our knowledge of the fallacies but because of his attention to prejudice and bias in scientific investigation, and the effect they could have on our beliefs. He spoke of false idols (1620, aphorisms 40–44) as having the same relation to the interpretation of nature that fallacies have to logic. The idol of the tribe is human nature which distorts our view of the natural world (it is a false mirror). The idol of the cave is the peculiarity of each individual man, our different abilities and education that affect how we interpret nature. The idols of the theatre are the acquired false philosophies, systems and methods, both new and ancient, that rule men’s minds. These three idols all fall into the category of explanations of why we may misperceive the world. A fourth of Bacon’s idols, the idol of the market place, is the one that comes closest to the Aristotelian tradition as it points to language as the source of our mistaken ideas: “words plainly force and overrule the understanding, and throw all into confusion, and lead men away into numberless empty controversies and idle fancies” (1620, aphorism 43). Although Bacon identifies no particular fallacies in Aristotle’s sense, he opens the door to the possibility that there may be false assumptions associated with the investigation of the natural world. The view of The New Organon is that just as logic is the cure for fallacies, so will the true method of induction be a cure for the false idols.

Antoine Arnauld and Pierre Nicole were the authors of Logic, or the Art of Thinking (1662), commonly known as the Port-Royal Logic. According to Benson Mates (1965, 214) it “is an outstanding early example of the ‘how to think straight’ genre.” The work includes chapters on sophisms, with the justification that “examples of mistakes to be avoided are often more striking than the examples to be imitated” (Bk. III, xix). The Port-Royal Logic does not continue Aristotle’s distinction between fallacies that are dependent on language and those that are not; instead there is a division between sophisms associated with scientific subjects (ibid.)—these are nearly all from the Sophistical Refutations —and those committed in everyday life and ordinary discourse (Bk III, xx). The division is not exclusive, with some of the sophisms fitting both classes.

The Port-Royal Logic includes eight of Aristotle’s original thirteen fallacies, several of them modified to fit the bent to natural philosophy rather than dialectical argumentation. Several kinds of causal errors are considered under the broad heading, non causa pro causa and they are illustrated with reference to scientific explanations that have assigned false causes for empirical phenomena. Also identified as a common fallacy of the human mind is post hoc, ergo propter hoc : “This happened following a certain thing, hence that thing must be its cause” (Bk. III, xix 3). Begging the questions is included and illustrated, interestingly, with examples drawn from Aristotelian science. Two new sophisms are included: one is imperfect enumeration, the error of overlooking an alternative, the other is a faulty (incomplete) induction, what we might call hasty generalization. Although the discussions here are brief, they mark the entry of inductive fallacies into the pool of present day recognized fallacies. Ignoratio elenchi retains its dialogical setting but is extended beyond the mere failure to contradict a thesis, “to attribut[ing] to our adversaries something remote from their views to gain an advantage over them, or to impute to them consequences we imagine can be drawn from their doctrines, although they disavow and deny them” (Bk. III, xix 1). The other Aristotelian fallacies included are accident, combination and division, secundum quid and ambiguity.

The sophisms of everyday life and ordinary discourse are eight in number and two of them, the sophisms of authority and manner, should be noticed. In these sophisms, external marks of speakers contribute to the persuasiveness of their arguments. Although authority is not to be doubted in church doctrines, in matters that God has left to the discernment of humans we can be led away from the truth by being too deferential. Here we find one of the earliest statements of the modern appeal to false authority: people are often persuaded by certain qualities that are irrelevant to the truth of the issue being discussed. Thus there are a number of people who unquestioningly believe those who are the oldest and most experienced, even in matters that depend neither on age nor experience, but only on mental insight (Bk. III, xx 6). To age and experience Arnauld and Nicole add noble birth as an unwarranted source of deference in matters intellectual (Bk. III, xx 7), and towards the end of their discussion they add the sophism of manner, cautioning that “grace, fluency, seriousness, moderation and gentleness” is not necessarily a mark of truth (Bk. III, xx 8). The authors seem to have the rhetorical flourishes of royal courtiers especially in mind.

It is John Locke who is credited with intentionally creating a class of ad -arguments, and inadvertently giving birth to the class of ad -fallacies. In An Essay Concerning Human Understanding (1690), he identified three kinds of arguments, the ad verecundiam , ad ignorantiam , and ad hominem arguments, each of which he contrasted with ad judicium arguments which are arguments based on “the foundations of knowledge and probability” and are reliable routes to truth and knowledge. Locke did not speak of ad -arguments as fallacies—that was left to others to do later—but rather as kinds of arguments “that men, in their reasoning with others, do ordinarily make use of to prevail on their assent; or at least so to awe them as to silence their opposition.” (Bk IV, xvii, 19–22).

Two of the ad arguments have developed beyond how Locke originally conceived them. His characterization of the ad verecundiam is considered the locus classicus of appeal-to-authority arguments. When it is a fallacy it is either on the ground that authorities (experts) are fallible or for the reason that appealing to authority is an abandonment of an individual’s epistemic responsibility. It seems unlikely, however, that Locke thought we should never rely on the expertise and superior knowledge of others when engaged in knowledge-gathering and argumentation. This leads us to consider what kind of authority Locke might have had in mind. In addition to epistemic and legal (command) authority there is also what might be called social authority, demanding respect and deference from others due to one’s higher social standing, something much more a part of seventeenth-century society than it is a part of ours. The language that Locke used in connection with the ad verecundiam , words like ‘eminency’, ‘dignity’, ‘breach of modesty’, and ‘having too much pride’ suggests that what he had in mind was the kind of authority that demands respect for the social standing of sources rather than for their expertise; hence, by this kind of authority a person could be led to accept a conclusion because of their modesty or shame, more so than for the value of the argument (see Goodwin 1998, Hansen 2006). Hence, we understand Locke better when we translate ad verecundiam literally, as “appeal to modesty.”

The argumentum ad hominem , as Locke defined it, has subsequently developed into three different fallacies. His original description was that it was a way “to press a man with consequences drawn from his own principles or concessions.” That is, to argue that an opponent’s view is inconsistent, logically or pragmatically, with other things he has said or to which he is committed. Locke’s observation was that such arguments do not advance us towards truth, but that they can serve to promote agreement or stall disagreement. To argue that way is not a fallacy but an acceptable mode of argumentation. Henry Johnstone (1952) thought it captured the essential character of philosophical argumentation. The modern descendants of the Lockean ad hominem are the abusive ad hominem which is an argument to the effect that a position should not be accepted because of some telling negative property of its espouser; the circumstantial ad hominem , an argument to the effect that someone’s position should be rejected because circumstances suggest that their view is the result of self-interested bias; and finally, the tu quoque ad hominem argument which attempts to deflect a criticism by pointing out that it applies equally to the accuser. Recent scholarship suggests that these post-Lockean kinds of ad hominem arguments are sometimes used fairly, and sometimes fallaciously; but none of them is what Locke described as the argumentum ad hominem .

Ad ignorantiam translates as “appeal to ignorance.” Locke’s characterization of this kind of argument is that it demands “the adversary to admit what they allege as a proof, or to assign a better.” The ignorance in question is comparative, it is not that the opponent has no evidence, it is that s/he has no better evidence. However, the inability of an opponent to produce a better argument is not sufficient reason to think the proponent’s argument must be accepted. Modern versions of this kind of argument take it as a fallacy to infer a proposition to be true because there is no evidence against it (see Krabbe, 1995).

The introduction and discussion of the ad -arguments appears almost as an afterthought in Locke’s Essay . It is found at the end of the chapter, “Of Reason,” in which Locke devotes considerable effort to criticizing syllogistic logic. Reasoning by syllogisms, he maintained, was neither necessary nor useful for knowledge. Locke clearly thought that the three ad -arguments were inferior to ad judicium arguments, but he never used the term ‘fallacy’ in connection with them, although he did use it in connection with errors of syllogistic reasoning.

Was Locke the first to discuss these kinds of arguments? Hamblin (1970, 161–62) and Nuchelmans (1993) trace the idea of ad hominem arguments back to Aristotle, and Locke’s remark that the name argumentum ad hominem was already known has been investigated by Finocchiaro (1974) who finds the term and the argument kind in Galileo’s writings more than a half-century before the Essay Concerning Human Understanding . And Arnauld and Nicole’s discussion of the sophism of authority, that “people speak the truth because they are of noble birth or wealthy or in high office,” which seems to be part of Locke’s ad verecundiam , was most likely known to him. Subsequently more ad -arguments were added to the four that Locke identified (see Watts, and Copi, below).

Isaac Watts in his Logick; or, The Right Use of Reason (1724), furthered the ad -argument tradition by adding three more arguments: argumentum ad fidem (appeal to faith), argumentum ad passiones (appeal to passion), and argumentum ad populum (a public appeal to passions). Like Locke, Watts does not consider these arguments as fallacies but as kinds of arguments. However, the Logick does consider sophisms and introduces “false cause” as an alternative name for non causa pro causa which here, as in the Port-Royal Logic, is understood as a fallacy associated with empirical causation. According to Watts it occurs whenever anyone assigns “the reasons of natural appearances, without sufficient experiments to prove them” (1796, Pt. III, 3 i 4). Another sophism included by Watts is imperfect enumeration or false induction, the mistake of generalizing on insufficient evidence. Also, the term ‘strawman fallacy’ may have its origins in Watts’s discussion of ignoratio elenchi : after having dressed up the opinions and sentiments of their adversaries as they please to make “images of straw”, disputers “triumph over their adversary as though they had utterly confuted his opinions” (1796, Pt. III 3 i 1).

Jeremy Bentham’s Handbook of Political Fallacies (1824) was written in the years leading up to the first Reform Bill (1832). His interest was in political argumentation, particularly in exposing the different means used by parliamentarians and law makers to defeat or delay reform legislation. Hence, it was not philosophy or science that interested him, but political debate. Fallacies he took to be arguments or topics that would through the use of deception produce erroneous beliefs in people (1824, 3). These tactics he (or his editor) divided into four classes: fallacies of authority, danger, delay and confusion. Bentham was aware of the developing ad -fallacies tradition since each of the thirty or so fallacies he described is also labelled as belonging either to the kind ad verecundiam (appeal to shame or modesty), ad odium (appeal to hate or contempt), ad metum (appeal to fear or threats), ad quietem (appeal to rest or inaction), ad judicium , and ad socordiam (appeal to postponement or delay). Most of Bentham’s fallacies have not become staples of fallacy theory but many of them show interesting insights into the motives and techniques of debaters (see e.g., Rudanko’s (2005, 2009) analyses of the ad socordiam ).

Bentham’s Handbook has not taken a central place in the history of fallacy studies (Hamblin 1970, 165–69); nevertheless, it is historically interesting in several respects. It discusses authority at length, identifying four conditions for reliable appeals to authority and maintaining that the failure of any one of them cancels the strength of the appeal. Fallacies of authority in political debate occur when authority “is employed in the place of such relevant arguments as might have been brought forward” (1824, 25). Bentham’s fear is that debaters will resort to “the authority” of traditional beliefs and principles instead of considering the advantages of the reform measures under discussion.

Under the heading “fallacies of danger” Bentham named a number of what he called vituperative fallacies—imputations of bad character, bad motive, inconsistency, and suspicious connections—which have as their common characteristic, “the endeavour to draw aside attention from the measure to the man , in such a way as to cause the latter’s badness to be imputed to the measure he supports, or his goodness to his opposition” (1824, 83). This characterization fits well with the way we have come to think of the ad hominem fallacy as a view disparaged by putting forth a negative characterization of its supporter or his circumstances.

Bentham places the fallacies in the immediate context of debate, identifying ways in which arguers frustrate the eventual resolution of disagreements by using insinuations of danger, delaying tactics, appeals to questionable authorities and, generally, confusing issues. Modern argumentation theorists who hold that any impediment to the successful completion of dialogical discussions is a fallacy, may find that their most immediate precursor was Bentham (see Grootendorst 1997).

Book III of Richard Whately’s Elements of Logic (1826) is devoted to giving an account of fallacies based on “logical principles,”. Whately was instrumental in the revival of interest in logic at the beginning of the nineteenth century and, being committed to deductivism, he maintained that only valid deductive inferences counted as reasoning. Thus, he took every fallacy to belong to either the class of deductive failures (logical fallacies) or the class of non-logical failures (material fallacies).

By ‘fallacy’ Whately meant “any unsound mode of arguing, which appears to demand our conviction, and to be decisive of the question at hand, when in fairness it is not”’ (Bk. III, intro.). The logical fallacies divide into the purely logical and the semi-logical fallacies. The purely logical fallacies are plain violations of syllogistic rules like undistributed middle and illicit process. The semi-logical fallacies mostly trade on ambiguous middle terms and are therefore also logical fallacies, but their detection requires extra-logical knowledge including that of the senses of terms [ 4 ] and knowledge of the subject matter (Bk. III, §2); they include, among others, the fallacies of ambiguity, and division and composition. The non-logical, material fallacies are also divided into two classes: fallacies with premises ‘unduly assumed,’ and fallacies of irrelevant conclusions. Begging the question fits under the heading of a non-logical, material fallacy in which a premise has been unduly assumed, and ignoratio elenchi is a non-logical, material fallacy in which an irrelevant conclusion has been reached. The ad -arguments are all placed under the last division as variants of ignoratio elenchi , but they are said to be fallacies only when they are used unfairly. Whately’s version of the ad hominem argument resembles Locke’s in that it is an ex concessis kind of argument: one that depends on the concessions of the person with whom one is arguing. From the concessions, one might prove that one’s opponent is ‘committed to p, ’ but an attempt to make it seem as if this constitutes a proof of the absolute (non-relative) proposition ‘ p ’ would be a fallacy. This kind of ad hominem fallacy can be seen as falling under the broader ignoratio elenchi category because what is proved is not what is needed.

The creation of the category of non-logical fallacies was not really a break with Aristotle as much as it was a break with what had become the Aristotelian tradition. Aristotle thought that some fallacies were due to unacceptable premises although these are not elaborated in Sophistical Refutations (see section 2.1.1 above). Whately’s creation of the category of non-logical fallacies solved the problem of what to do with begging the question which is not an invalid form of argument, and it also created a place in fallacy taxonomy for the ad -fallacies.

John Stuart Mill’s contribution to the study of fallacies is found in Book V of his comprehensive A System of Logic, Ratiocinative and Inductive , first published in 1843. It stands out most strikingly for placing the study of fallacies within his framework of inductive reasoning, a direct rejection of Whately’s deductivist approach to reasoning and fallacies. Mill held that only inductive reasoning counts as inferring and accordingly he introduces new categories as well as a new classification scheme for fallacies.

Mill drew a division between the moral and the intellectual causes of fallacies. The former are aspects of human nature such as biases and indifference to truth which incline us to make intellectual mistakes. These dispositions are not themselves fallacies. It is the intellectual errors, the actual taking of insufficient evidence as sufficient, that are fallacious. The various ways in which this can happen are what Mill took as the basis for classifying fallacies. “A catalogue of the varieties of evidence which are not real evidence,” he wrote, “is an enumeration of fallacies” (1891, Bk.V iii §1).

Mill divided the broad category of argument fallacies into two groups: those in which the evidence is distinctly conceived and those in which it is indistinctly conceived. Fallacies falling under evidence indistinctly conceived (Bk. V, vii) were further described as fallacies of confusion. These result from an indistinct conception of the evidence leading to a mistaking of its significance and thereby to an unsupported conclusion. Some of the traditional Aristotelian fallacies such as ambiguity, composition and division, petitio principii , and ignoratio elenchi , are placed in this category. Although Mill followed Whately closely in his exposition of the fallacies of confusion, he does not mention any ad -arguments in connection with ignoratio elenchi .

As for the category of fallacies of evidence distinctly conceived, it too is divided. The two sub-classes are fallacies of ratiocination (deduction) and fallacies of induction. The deductive fallacies (Bk.V, vi) are those that explicitly break a rule of the syllogism, such as the three-term rule. But also included are the conversion of universal affirmatives and particular negatives (“All PS” does not follow from “All SP,” and “Some P not S” does not follow from “Some S not P”). Also included in this category is the secundum quid fallacy.

The other sub-class of fallacies distinctly conceived bring out what is distinctive about Mill’s work on the fallacies: that it is the first extensive attempt to deal with fallacies of induction. He divided inductive fallacies into two further groups: fallacies of observation (V, iv) and fallacies of generalization (Bk. V, v). Fallacies of observation can occur either negatively or positively. Their negative occurrence consists in non-observation in which one has overlooked negatively relevant evidence. This is similar to what the Port-Royal Logic considered a faulty enumeration, and one of Mill’s examples is the continued faith that farmers put in the weather forecasts found in almanacs despite their long history of false predictions. Observation fallacies occur positively when the mistake is based on something that is seen wrongly, i.e., taken to be something that it is not. Such mal-observations occur when we mistake our inferences for facts, as in our inference that the sun rises and sets (Bk. V, iv, 5).

Fallacies of generalization, the other branch of inductive fallacies, result from mistakes in the inductive process which can happen in several ways. As one example, Mill pointed to making generalizations about what lies beyond our experience: we cannot infer that the laws that operate in remote parts of the universe are the same as those in our solar system (Bk. V, v, 2). Another example is mistaking empirical laws stating regularities for causal laws—his example was because women as a class have not hitherto equalled men as a class, they will never be able to do so (Bk. V, v, 4). Also placed in the category of fallacies of generalization is post hoc ergo propter hoc , which tends to single out a single cause when there are in reality many contributing causes (Bk. V, v, 5). Analogical arguments are identified as a false basis for generalizations; they are “at best only admissible as an inconclusive presumption, where real proof is unattainable” (Bk. V, v, 6).

Mill also included what he calls fallacies of inspection, or a priori fallacies (Bk. V, iii) in his survey of fallacies. These consist of non-inferentially held beliefs, so they fit the belief conception of fallacies rather than the argument conception. Among Mill’s examples of a priori fallacies are metaphysical assumptions such as that distinctions of language correspond to distinctions in nature, and that objects cannot affect each other at a distance. Even the belief in souls or ghosts is considered an a priori fallacy. Such beliefs will not withstand scrutiny, thought Mill, by the inductive method strictly applied.

A System of Logic is the most extensive work on fallacies since Aristotle’s Sophistical Refutations . Mill’s examples are taken from a wide range of examples in science, politics, economics, religion and philosophy. His classificatory scheme is original and comprehensive. Frederick Rosen (2006) argues that Mill’s pre-occupation with the detection and prevention of fallacies is part of what motivates the celebrated second chapter of On Liberty . Despite these considerations, the Logic is not much referenced by fallacy theorists.

Irving Copi’s Introduction to Logic —an influential text book from the mid-twentieth century—defines a fallacy as “a form of argument that seems to be correct but which proves, upon examination, not to be so.” (1961, 52) The term ‘correct’ is sufficiently broad to allow for both deductive invalidity, inductive weakness, as well as some other kinds of argument failure. Of the eighteen informal fallacies Copi discusses, eleven can be traced back to the Aristotelian tradition, and the other seven to the burgeoning post-Lockean ad -fallacy tradition.

The first division in Copi’s classification is between formal and informal fallacies. Formal fallacies are invalid inferences which “bear a superficial resemblance” to valid forms of inference, so these we may think of as deductive fallacies. They include affirming the consequent, denying the antecedent, the fallacy of four terms, undistributed middle, and illicit major. Informal fallacies are not characterized as resembling formally valid arguments; they gain their allure some other way. One division of informal fallacies is the fallacies of relevance which are “errors in reasoning into which we may fall because of carelessness and inattention to our subject matter” (1961, 53). This large class of fallacies includes accident, converse accident, false cause, petitio principii , complex question, ignoratio elenchi , ad baculum , ad hominem abusive, ad hominem circumstantial, ad ignorantiam , ad misericordiam , ad populum , and ad verecundiam . The other division of informal fallacies is called fallacies of ambiguity and it includes equivocation, amphiboly, accent, composition and division.

It seems that Copi took Whately’s category of semi-logical fallacies and moved them under a new heading of ‘informal fallacies,’ presumably for the reason that extra-logical knowledge is needed to uncover their invalidity. This has the result that the new wide category of informal fallacies is a mixed bag: some of them are at bottom logical failures (equivocation, composition, ad misericordiam ) and some are logically correct but frustrate proof (begging the question, ignoratio elenchi ). [ 5 ] Copi’s classification, unlike Whately’s which sought to make a distinction on logical grounds, may be seen as based on three ways that fallacies resemble good arguments: formal fallacies have invalid forms that resemble valid forms, fallacies of ambiguity resemble good arguments through the ambiguity of terms, and fallacies of relevance exploit psychological (non-logical) associations. Hence, we may think of Copi’s divisions as between logical, semantic and psychological fallacies.

Copi’s treatment of the fallacies is a fair overview of the traditional list of fallacies, albeit he did not pretend to do any more than give an introduction to existing fallacy-lore for beginning logic students. Hamblin (1970, ch. 1) criticized Copi’s work, along with that of several others, and gave it the pejorative name, “the standard treatment of fallacies.” His criticisms rang true with many of his readers, thereby provoking contempt for the traditional treatment of fallacies as well as stimulating research in what we may call the new, or post-Hamblin, era, of fallacy studies. Let us next consider some of these developments.

3. New approaches to fallacies

A common complaint since Whately’s Elements of Logic is that our theory and teaching of fallacies are in want of improvement—he thought they should be put on a more logical footing to overcome the loose and vague treatments others had proffered.

It is on Logical principles therefore that I propose to discuss the subject of Fallacies. … the generality of Logical writers have usually followed so opposite a plan. Whenever they have to treat of anything that is beyond the mere elements of Logic, they totally lay aside all reference to the principles they have been occupied in establishing and explaining, and have recourse to a loose, vague, and popular kind of language … [which is] … strangely incongruous in a professional Logical treatise. (1875, III, intro.)

Charles Hamblin’s 1970 book, Fallacies , revives Whately’s complaint. We may view Fallacies as the dividing line between traditional approaches to the study of fallacies and new, contemporary approaches. At the time of its publication it was the first book-length work devoted to fallacies in modern times. The work opens with a critique of the standard treatment of fallacies as it was found in mid-twentieth century textbooks; then, in subsequent chapters, it takes a historical turn reviewing Aristotle’s approach to fallacies and exploring the tradition it fostered (as in the previous section of this entry). Other historically-oriented chapters include one on the Indian tradition, and one on formal fallacies. Hamblin’s more positive contributions to fallacy studies are concentrated in the book’s later chapters on the concept of argument, formal dialectics, and equivocation.

What Hamblin meant by “the standard treatment of fallacies” was:

The typical or average account as it appears in the typical short chapter or appendix of the average modern textbook. And what we find in most cases, I think it should be admitted, is as debased, worn-out and dogmatic a treatment as could be imagined—incredibly tradition bound, yet lacking in logic and in historical sense alike, and almost without connection to anything else in modern Logic at all. (1970, 12)

Let us consider what came before Hamblin as the traditional approach to fallacies and what comes after him as new approaches. The new approaches (since the 1970’s) show a concern to overcome Hamblin’s criticisms, and they also vie with each to produce the most defensible alternative to the traditional approach. One thing that nearly all the new approaches have in common is that they reject what Hamblin presents as the nearly universally accepted definition of “fallacy” as an argument “that seems to be valid but is not so” (1970, 12). Although this definition of fallacy is not nearly as widely accepted as Hamblin intimated (see Hansen 2002), others have taken to calling it “the standard definition of fallacies” and for convenience we can refer to it as SDF. SDF has three necessary conditions: a fallacy (i) is an argument, (ii) that is invalid, and (iii) appears to be valid. These can be thought of as the argument condition, the invalidity condition and the appearance condition. All three conditions have been brought into question.

Maurice Finocchiaro continued Hamblin’s criticism of the modern textbook treatment of fallacies, observing that they contain very few examples of actual fallacies, leading him to doubt the validity of ‘fallacy’ as a genuine logical category. Although he allows that errors in reasoning are common in real life, he thinks that “types of logically incorrect arguments”—fallacies—are probably not common (1981, 113). For that reason Finocchiaro prefers to speak of fallacious arguments —by which he means arguments in which the conclusion fails to follow from the premises—rather than fallacies (1987, 133). He further distances himself from SDF by not considering the appearance condition.

Finocchiaro distinguishes six ways in which arguments can be fallacious. (1) Formal fallaciousness is simply the case where the conclusion does not follow validly from the premises; this type of error can be demonstrated by producing a suitable analogous counter-example in which the premises are true and the conclusion is false. (2) Explanatory fallaciousness occurs when a specified conclusion follows with no more certainty from the given premises than does a rival conclusion; it occurs most often in the context of proposing explanatory hypotheses. (3) Presuppositional fallaciousness occurs in those cases where an argument depends on a false presupposition; this kind of fallaciousness is demonstrated by making a sound argument showing the presupposition to be false. (4) Positive fallaciousness occurs when the given premises, complemented by other propositions taken as true, are shown to support a conclusion inconsistent with the given conclusion. (5) Semantical fallaciousness results from the ambiguity of terms; the conclusion will follow if the sense given to the term in the premises makes the premises false, but if the other sense is ascribed to the term, making the premises true, the conclusion does not follow (it becomes an instance of formal fallaciousness). (6) Finally, Finocchiaro singles out persuasive fallaciousness , in which the conclusion does not follow from the premises because it is the same as one of the premises. As a test of completeness of this six-fold division of fallaciousness, Finocchiaro (1987) observes that it is adequate to classify all the kinds of errors which Galileo found in the arguments of the defenders of the geocentric view of the solar system.

Gerald Massey (1981) has voiced a strong objection to fallacy theory and the teaching of fallacies. He argues that there is no theory of invalidity—no systematic way to show that an argument is invalid other than to show that it has true premises and a false conclusion (1981, 164). Hence, there is an asymmetry between proving arguments valid and proving them invalid: they are valid if they can be shown to be an instance of a valid form, but they are not proved invalid by showing that they are an instance of an invalid form, because both valid and invalid arguments instantiate invalid forms. Thus, showing that a natural language argument is an instance of an invalid form does not preclude the possibility that it is also an instance of a valid form, and therefore valid. Since upholders of SDF maintain that fallacies are invalid arguments, Massey’s asymmetry thesis has the consequence that no argument can be convicted of being a fallacy on logical grounds. [ 6 ]

The informal logic approach to fallacies is taken in Johnson and Blair’s Logical Self-Defence , a textbook first published in 1977. It was prompted in part by Hamblin’s indictment of the standard treatment and it further develops an initiative taken by Kahane (1971) to develop university courses that were geared to everyday reasoning. Johnson and Blair’s emphasis is on arming students to defend themselves against fallacies in everyday discourse, and a fundamental innovation is in their conception of a good argument. In place of a sound argument—a deductively valid argument with true premises—Johnson and Blair posit an alternative ideal of a cogent argument , one whose premises are acceptable, relevant to and sufficient for its conclusion. Acceptability replaces truth as a premise requirement, and the validity condition is split in to two different conditions, premise relevance and premise sufficiency. Acceptability is defined relative to audiences—the ones for whom arguments are intended—but the other basic concepts, relevance and sufficiency, although illustrated by examples, remain as intuitive, undefined concepts (see Tindale, 2007). Premise sufficiency (strength) is akin to probability in that it is a matter of degree but Johnson and Blair do not pursue giving it numerical expression.

The three criteria of a cogent argument, individually necessary and jointly sufficient, lead to a conception of fallacy as “any argument that violates one of the criteria of good argument … and is committed frequently in argumentative discourse” (1993, 317–18). This shares only one condition with SDF: that a fallacy is an argument. (Deductive) validity is replaced with the broader concept sufficiency, and the appearance condition is not included. Johnson (1987) argued that the appearance condition makes the occurrence of fallacies too subjective since how things appear may vary from perceiver to perceiver, and it should therefore be replaced by a frequency requirement. To be a fallacy, a mistake must occur with sufficient frequency to be worth our attention.

The adoption of the concept of a cogent argument as an ideal has several consequences. The category of fallacies with problematic premises (reminiscent of Whately’s “premises unduly assumed”) shows a concern with argument evaluation over and beyond logical or inference evaluation, drawing the informal logic approach away from purely logical concerns towards an epistemic conception of fallacies. Having both sufficiency and relevance as criteria (instead of the single validity criterion) has the benefit of allowing the making of nuanced judgments about the level of premise support: for example, we might say that an argument’s premises, although insufficient, are nevertheless positively relevant to the conclusion. Irrelevant premise fallacies are those with no premise support at all, whereas insufficient premise fallacies are those in which there is some support, but not enough of it. The informal logicians’ conception of fallacies is meant to be broader and more suitable to natural language argumentation than would be a conception tied only to deductive invalidity.

Johnson and Blair concern themselves exclusively with informal fallacies. Many of the familiar Aristotelian fallacies that are part of the standard treatment are missing from their inventory (e.g., accident, composition and division) and the ones retained find themselves in new categories: begging the question and ambiguity are together under the heading of Problematic Premise; appeals to authority and popularity are placed under the heading of Hasty Conclusion fallacies; ad hominem is among the fallacies that belong in the third category, Fallacies of Irrelevant Reason. This new list of fallacies has a different bent than many earlier lists, being more geared to deal with arguments in popular, everyday communication than philosophical or scientific discourse; this is evident both by the omission of some of the traditional fallacies as well as by the introduction of new ones, such as dubious assumption, two wrongs, slippery slope, and faulty analogy.

The kinds of mistakes one can make in reasoning are generally thought to be beyond enumeration and, hence, it has been maintained that there can be no complete stock of fallacies that will guard against every kind of mistake. Johnson and Blair’s approach is responsive to this problem in that it allows the names of the classes of fallacies — ‘unacceptable premise,’ ‘irrelevant reason’ and ‘hasty conclusion’ — to stand for fallacies themselves, fallacies broad-in-scope; i.e., to serve “both as general principles of organization, and as back-ups to fill in any gaps between specific labels belonging within each genus” (1993, 52). Hence, any violation of one of the criteria of a cogent argument can be considered a fallacy.

In addition to this alternative theoretical approach to fallacies built on the three criteria of a cogent argument—an approach also taken up by others [ 7 ] —informal logic’s contribution to fallacy studies lies in its attempts to provide better analyses of fallacies, a programme pursued by a large number of researchers, including Govier (1982) on the slippery slope, Wreen (1989) on the ad baculum , Walton (1991) on begging the question, Brinton (1995) on the ad hominem , Freeman (1995) on the appeal to popularity, and Pinto (1995) on post hoc ergo propter hoc .

John Woods also despairs of the standard treatment but he sees in it something of importance; namely that the fallacies most often reviewed in introductory level logic textbooks “are a kind of caricature of their associated improprieties, which lie deeply imbedded in human practice” (Woods 1992, 25). The fallacies are then behavioural symptoms of kinds of irrationality to which humans are highly susceptible, and that makes them an important subject for study because they say something about human nature. Therefore, the problem with the standard treatment, according to Woods, is not that it is a misdirected research programme, but rather that it has been poorly carried out, partly because logicians have failed to appreciate that a multi-logical approach is necessary to understand the variety of fallacies. This idea, pursued jointly by Woods and Douglas Walton (1989), is that, for many of the fallacies standard formal logic is inadequate to uncover the unique kind of logical mistakes in question—it is too coarse conceptually to reveal the unique character of many of the fallacies. To get a satisfactory analysis of each of the fallacies they must be matched with a fitting logical system, one that has the facility to uncover the particular logical weakness in question. Inductive logic can be employed for analysis of hasty generalization and post hoc ergo propter hoc ; relatedness logic is appropriate for ignoratio elenchi ; plausible reasoning theory for the ad verecundiam , and dialectical game theory for begging the question and many questions. Woods (1992, 43) refers to this approach to studying the fallacies as methodological pluralism. Thus, like the informal logicians, there is here an interest in getting the analyses of each of the fallacies right, but the Woods and Walton approach involves embracing formal methods, not putting them aside.

Woods (2013) has continued his research on fallacies, most recently considering them in the context of what he calls a naturalized logic (modelled on Quine’s naturalized epistemology). The main point of this naturalizing move is that a theory of reasoning should take into account the abilities and motivations of reasoners. Past work on the fallacies has identified them as failing to satisfy the rules of either deductive or inductive logic, but Woods now wants to consider the core fallacies in light of what he calls third-way reasoning (comparable to non-monotonic reasoning), an account of the cognitive practices that closely resemble our common inferential practices. From the perspective of third-way reasoning the “rules” implicit in the fallacies present themselves as heuristic directives to reasoners rather than as fallacies; hence, it may be that learning from feedback (having errors corrected) is less trouble than learning the rules to avoid fallacies in the first place (Woods 2013, p. 215). Woods illustrates his point by recalling many of the fallacies he originally identified in his 1992 paper, and subjecting them to this revised model of analysis thereby overturning the view that these types of argument are always to be spurned.

SDF may be seen as closely tied to the logical approach to fallacies—the fault in arguments it singles out is their deductive invalidity. But this conception of fallacies turns out to be inadequate to cover the variety of the core fallacies in two ways: it is too narrow because it excludes begging the question which is not invalid, and it is too wide because it condemns good but non-deductive arguments as fallacies (given that they also satisfy the appearance condition) because they are invalid. Even if we replace the invalidity condition in SDF with some less stringent standard of logical weakness which could overcome the “too wide” problem, it would still leave the difficulty of accounting for the fallacy of begging the question unsolved.

Siegel and Biro (1992, 1995) hold an epistemic account of fallacies, contrasting their view with dialectical/rhetorical approaches, because matters extraneous to arguments, such as being a practice that leads to false beliefs or not being persuasive, are not in their view a sufficient condition to make an argument a fallacy. They take the position that “it is a conceptual truth about arguments that their central … purpose is to provide a bridge from known truths or justified beliefs to as yet unknown … truths or as yet unjustified beliefs” (1992, 92). Only arguments that are “epistemically serious” can accomplish this; that is, only arguments that satisfy the extra-formal requirement that premises are knowable independently of their conclusions, and are more acceptable epistemically than their conclusions, can fulfill this function. A purely logical approach to argument will not capture this requirement because arguments of the same valid form, but with different contents, may or may not be epistemically serious, depending on whether the premises are epistemically acceptable relative to the conclusion.

Modifying Biro’s (1977, 265–66) examples we can demonstrate how the requirement of epistemic seriousness plays out with begging the question. Consider these two arguments:

All men are mortal; Obama is a man; So, Obama is mortal.

All members of the committee are old Etonians; Fortesque is a member of the committee; Fortesque is an old Etonian.

In the first argument the premises are knowable independently of the conclusion. The major premise can be deduced from other universal premises about animals, and the minor premise, unlike the conclusion which must be inferred, can be known by observation. Hence, this argument does not beg the question. However, in the second argument (due to Biro, 1977) given the minor premise, the major cannot be known to be true unless the conclusion is known to be true. Consequently, on the epistemic approach to fallacies taken by Biro and Siegel, the second argument, despite the fact that it is valid, is non-serious, it begs the question, and it is a fallacy. If there was some independent way of knowing whether the major premise was true, such as that it was a bylaw that only old Etonians could be committee members, the argument would be a serious one, and not beg the question.

Biro and Siegel’s epistemic account of fallacies is distinguishable in at least three ways. First, it insists that the function of arguments is epistemic, and therefore anything that counts as a fallacy must be an epistemic fault, a breaking of a rule of epistemic justification. But since logical faults are also epistemic faults, the epistemic approach to fallacies will include logical fallacies, although these must also be explicable in terms of epistemic seriousness. Second, since the epistemological approach does not insist that all justification must be deductive, it allows the possibility of their being fallacies (as well as good arguments) by non-deductive standards, something precluded by SDF. Finally, we notice that the appearance condition is not considered a factor in this discussion of fallacies.

Ulrike Hahn and Mike Oaksford (2006a, 2006b) see themselves as contributing to the epistemic approach to fallacy analysis by developing a probabilistic analysis of the fallacies. It is part of their programme for a normative theory of natural language argumentation. They are motivated by what they perceive as the shortcomings in other approaches. The logical (deductive) approach falls short in that it simply divides arguments into valid and invalid arguments thereby failing to appreciate that natural language arguments come in various degrees of strength. The alternative approaches to fallacies, given by procedural (dialectical) and consensual accounts, they criticize on the basis that they fail to address the central problem raised by the fallacies: that of the strength of the reason-claim complex. In Hahn and Oaksford’s view the strength or weakness of the classical fallacies (they are concerned mostly with the post-Aristotelian ones) is not a result of their structure or their context of use. It is instead a matter of the relationship between the evidence and the claim (the contents of the premises and the conclusion). Evaluation of this relationship is thought to be best captured by a probabilistic Bayesian account; accordingly, they adapt Bayes’ theorem to arguments evaluation with the proviso that the probabilities are subjective degrees of belief, not frequencies. “An argument’s strength,” they write, “is a function of an individual’s initial level of belief in the claim, the availability and observation of confirmatory (or disconfirmatory) evidence, and the existence and perceived strength of competing hypotheses” (Corner, et al. 1145). With Korb (2003) they view a fallacy as an argument with a low probability on the Bayesian model.

Since the variance in input probabilities will result in a range of outputs in argument strength, this probabilistic approach has the potential to assign argument strengths anywhere between 0 and 1, thereby allowing that different tokens of one argument type can vary greatly in strength, i.e., some will be fallacies and others not. Also, and this seems to concur with our experience, different arguers may disagree on the strength of the same arguments since they can differ in the assignments of the initial probabilities. Hahn and Oaksford also claim as advantages for their normative theory that it gives guidance for persuasion since it takes into account the initial beliefs of audiences. Moreover, their approach contributes to the study of belief change; that is, to what extent our confidence in the conclusion changes with the availability of new evidence.

Some of the most active new researchers on fallacies take a dialectical and/or dialogical approach. This can be traced back to Hamblin (1970, ch. 8) and Lorenzen’s (1969) dialogue theory. The panacea for fallacies that Whately recommended was more logic; Hamblin, however, proposed a shift from the logical to the dialectical perspective.

[W]e need to extend the bounds of Formal Logic; to include features of dialectical contexts within which arguments are put forward. To begin with, there are criteria of validity of argument that are additional to formal ones: for example, those that serve to proscribe question-begging. To go on with, there are prevalent but false conceptions of the rules of dialogue, which are capable of making certain argumentative moves seem satisfactory and unobjectionable when, in fact, they conceal and facilitate dialectical malpractice. (Hamblin 1970, 254)

The proposal here is to shift the study of fallacies from the contexts of arguments to the contexts of dialogues (argumentation), formulate rules for reasonable dialogue activity, and then connect fallacies to failures of rule-following. Barth and Martens’s paper (1977), which studied the argumentum ad hominem by extending Lorenzen’s dialogue tableaux method to include the definitions of the concepts “line of attack” and “winning strategy,” leads to a conception of fallacies as either failures to meet one of the necessary conditions of rational dialogical argumentation, or failures to satisfy sufficient conditions as specified by production rules of the dialogical method (1977, 96).

The Barth and Martens paper is a bridge between the earlier (quasi-) formal and subsequent informal dialectical theories, and is explicitly acknowledged as a major influence by the Pragma-dialectical theory, the brainchild of Frans van Eemeren and Rob Grootendorst (1984). Rather than beginning from a logical or epistemological perspective they start with the role of argumentation in overcoming interpersonal disagreements. The Pragma-dialecticians propose that inter-personal argumentation can be analysed as two-party-discussions having four analytical stages: a confrontation stage in which the participants become aware of the content of their disagreement; an opening stage in which the parties agree (most likely implicitly) to shared starting points and a set of rules to govern the ensuing discussion; an argumentation stage wherein arguments and doubts about arguments are expressed and recognized; and a final stage in which a decision about the initial disagreement is made, if possible, based on what happened in the argumentation stage.

The Pragma-dialectical theory stipulates a normative ideal of a critical discussion which serves both as a guide to the reconstruction of natural language argumentation, as well as a standard for the evaluation of the analysed product of reconstruction. A set of ten rules has been proposed as constitutive of the critical-discussion ideal, and the proponents of the theory believe that rational arguers would accept them. If followed by both parties to the disagreement, the rules constrain the argumentation decision procedure such that any resolution reached will be deemed reasonable, and “every violation of any of the rules of the discussion procedure for conducting a critical discussion” will be a fallacy (2004, 175). The rules range over all the four stages of argumentation: at the confrontation stage there is a rule which says one may not prevent the other party from expressing their view; for the argumentation stage there is a rule which requires argumentation to be logically strong and in accord with one or another of three general argumentation schemes; at the closing stage there is a rule that the participants themselves are to decide which party was successful based on the quality of the argumentation they have made: if the proponent carries the day, the opponent should acknowledge it, and vice versa .

The Pragma-dialectical theory proposes that each of the core fallacies can be assigned a place as a violation of one of the rules of a critical discussion. For example, the ad baculum fallacy is a form of intimidation that violates the rule that one may not attempt to prevent one’s discussion partner from expressing their views; equivocation is a violation of the rule that formulations in arguments must be clear and unambiguous; post hoc ergo propter hoc violates the rule that arguments must be instances of schemes correctly applied. Moreover, on this theory, since any rule violation is to count as a fallacy this allows for the possibility that there may be hitherto unrecognized “new fallacies.” Among those proposed are declaring a standpoint sacrosanct because that breaks the rule against the freedom to criticize points of view, and evading the burden of proof which breaks the rule that you must defend your standpoint if asked to do so (see van Eemeren 2010, 194).

Clearly not all the rules of critical discussions apply directly to arguments. Some govern other goal-frustrating moves which arguers can make in the course of settling a difference of opinion, such as mis-allocating the burden of proof, asking irrelevant questions, suppressing a point of view, or failing to clarify the meaning of one’s argumentation. In short, the Pragma-dialectical rules of a critical discussion are not just rules of logic or epistemology, but rules of conduct for rational discussants, making the theory more like a moral code than a set of logical principles. Accordingly, this approach to fallacies rejects all three of the necessary conditions of SDF: a fallacy need not be an argument, thus the invalidity condition will not apply either, and the appearance condition is excluded because of its subjective character (Van Eemeren and Grootendorst 2004, 175).

The Pragma-dialectical analysis of fallacies as rule-breakings in a procedure for overcoming disagreements has recently been expanded to take account of the rhetorical dimension of argumentation. Pragma-dialectics takes the rhetorical dimension to stem from an arguer’s wish to have their view accepted which leads dialoguers to engage in strategic maneuvering vis-à-vis their dialogue partners. However, this desire must be put in balance with the dialectical requirement of being reasonable; that is, staying within the bounds of the normative demands of critical discussions. The ways of strategic maneuvering identified are basically three: topic selection, audience orientation, and the selection of presentational devices, and these can be effectively deployed at each stage of argumentation (Van Eemeren 2010, 94). “All derailments of strategic maneuvering are fallacies,” writes van Eemeren (2010, 198), “in the sense that they violate one or more of the rules for critical discussion and all fallacies can be viewed as derailments of strategic maneuvering.” This means that all fallacies are ultimately attributable to the rhetorical dimension of argumentation since, in this model, strategic maneuvering is the entry of rhetoric into argumentation discussions. “Because each fallacy has, in principle, sound counterparts that are manifestations of the same mode of strategic maneuvering” it may not appear to be a fallacy and it “may pass unnoticed” (Van Eemeren 2010, 199). Nevertheless, Pragma-dialectics prefers to keep the appearance condition outside the definition of ‘fallacy’, treating the seeming goodness of fallacies as a sometime co-incidental property, rather than an essential one.

Argumentation evaluation on the Pragma-dialectical approach is done with an eye to a single ideal model of argumentation. This approach has been challenged by Douglas Walton who has written more about fallacies and fallacy theory than anyone else. He has published individual monographs on many of the well-known fallacies, among them, Begging the Question (1991), Slippery Slope Arguments (1992), Ad Hominem Arguments (1998), and a comprehensive work on fallacy theory, A Pragmatic Theory of Fallacy (1995). Over the years his views have evolved. He has referred to his theory as “the Pragmatic theory,” and like the Pragma-dialectical theory it has a dialectical/dialogical basis; however, Walton envisions a number of distinct normative dialectical frameworks (persuasion dialogue, inquiry dialogue, negotiation dialogue, etc.) rather than the single model of a critical discussion proposed by Pragma-dialectics. Postulating different kinds of dialogues with different starting points and different goals, thinks Walton, will bring argumentation into closer contact with argumentation reality. At one point Walton had the idea that fallacies happened when there was an illicit shift from one kind of a dialogue to another (1995, 118–23), for example, using arguments appropriate for a negotiation dialogue in a persuasion dialogue, but more recently he has turned to other ways of explicating fallacies.

Although Walton recognizes the class of formal fallacies, his main interest is in informal fallacies, especially the ones associated with argumentation schemes. The idea of an argumentation scheme is central to Walton’s theory. Schemes are patterns of commonly used kinds of defeasible reasoning/argumentation such as appeals to expert opinion and ad hominem arguments. Schemes do not identify fallacies but rather argument kinds that are sometimes used fairly, and, other times, fallaciously. With each kind of scheme is associated a set of critical questions which guide us in deciding whether a given use of an argument is correct, weak or fallacious. So, if we consider:

\(E\) is an expert in subject area \(S\); \(E\) asserts \(p\) based on \(E\)’s knowledge of \(S\); So, \(p\).

to be the scheme for the appeal-to-expertise kind of argument, [ 8 ] then there will be a question for each premise: Is \(E\) really an expert in \(S\)? Did \(E\) say \(p\) when s/he was acting in her/his professional capacity? (… or did s/he blurt it out while drunk at an association party?). If the answer to both questions is Yes, then the argument creates a presumption for the conclusion—but not a guarantee, for the reasoning is defeasible: other information may come to light that will override the presumption. If one of the questions cannot be answered clearly this is an indication that the argument is weak, and answering No to either of the two questions cancels the presumption for the conclusion, i.e., makes the argument into a bad argument from expert opinion. If the bad argument has “a semblance of correctness about it in [the] context, and poses a serious obstacle to the realization of the goal of the dialog,” then it is a fallacy (2011, 380). [ 9 ]

The definition of fallacy Walton proposes (1995, 255) has five parts. A fallacy:

• an argument (or at least something that purports to be an argument) that
• falls short of some standard of correctness;
• is used in a context of dialogue;
• has a semblance of correctness about it; and
• poses a serious problem to the realization of the goal of the dialogue.

Here we find that Walton has relaxed two of the necessary conditions of SDF. Purporting to be an argument is enough (it doesn’t really have to be an argument), while falling short of a standard (one that will vary with the kind of dialogue under consideration) replaces the invalidity condition. However, the appearance condition, here expressed as fallacies having a semblance of correctness about them, remains in full force. The two extra conditions added to fallacy are that they occur only in contexts of dialogue and that they frustrate the realization of the goal of the kind of dialogue in which they occur. In insisting on this dialogical dimension, Walton is in full sympathy with those who think that fallacies can only be rightly analysed within a dialectical framework similar to the ones Aristotle originally studied, and later better defined by Hamblin and Lorenzen. Walton volunteers a shorter version of the definition of a fallacy as “a deceptively bad argument that impedes the progress of a dialogue” (1995, 256).

Walton divides fallacies into two kinds: paralogisms and sophisms. A paralogism is “the type of fallacy in which an error of reasoning is typically committed by failing to meet some necessary requirement of an argumentation scheme” whereas “the sophism type of fallacy is a sophistical tactic used to try to unfairly get the best of a speech partner in an exchange of arguments” (2010, 171; see also 1995, 254). Paralogisms are instances of identifiable argumentation schemes, but sophisms are not. The latter are associated more with infringing a reasonable expectation of dialogue than with failing some standard of argument, (2011, 385; 2010, 175). A further distinction is drawn between arguments used intentionally to deceive and arguments that merely break a maxim of argumentation unintentionally. The former count as fallacies; the latter, less condemnable, are blunders (1995, 235).

Among the informal paralogisms Walton includes: ad hominem , ad populum , ad misericordiam , ad ignorantiam , ad verecundiam , slippery slope, false cause, straw man, argument from consequences, faulty analogy, composition and division. In the category of sophisms he places ad baculum , complex question, begging the question, hasty generalization, ignoratio elenchi , equivocation, amphiboly, accent, and secundum quid . He also has a class of formal fallacies very much the same as those identified by Whately and Copi. The largest class in Walton’s classification is the one associated with argumentation schemes and ad -arguments, and these are the ones that he considers to be the most central fallacies. Nearly all the Aristotelian fallacies included find themselves relegated to the less studied categories of sophisms. Taking a long look at the history of fallacies, then, we find that the Aristotelian fallacies are no longer of central importance. They have been replaced by the fallacies associated with the ad -arguments.

Another recent approach comes from virtue argumentation theory (modelled on virtue epistemology). Virtue argumentation theory is characterized by a distinct set of virtues thought to be essential to good argumentation: willingness to engage in argumentation, willingness to listen to others and willingness to modify one’s own position (see, e.g., Cohen 2009). These may be supplemented with epistemic virtues and even in some cases moral virtues. Although virtues and vices are dispositions of arguers and fallacies are arguments, it is claimed that good argumentation generally results from the influence of argumentation virtues and bad argumentation (including the fallacies) arise because of the vices of arguers.

Taking the Aristotelian view that virtues are a mean between opposite kinds of vices, fallacious arguments can be seen as resulting from arguers moving in one or another direction away from a mean of good argumentation. Aberdein (2013, 2016) especially has developed this model for understanding many of the fallacies. We can illustrate the view by considering appeals to expertise: the associated vices might be too little respect for reliable authorities at one extreme and too much deference to authorities at the other extreme. Aberdein develops the fallacies-as-argumentation-vices analysis in some detail for other of the ad-arguments and sketches how it might be applied to the other core fallacies, suggesting it can profitably be extended to all of them.

All the fallacies, it is claimed, can be fitted in somewhere in the classification of argumentational vices, but the converse is not true although it is possible to bring to light other shortcomings to which we may fall prey in argumentation. Another aspect of the theory is that it distributes argumentation vices among both senders and audiences. Speakers may infect their arguments with vices when they are, for example, closed minded or lack respect for persons, and audiences can contribute to fallaciousness by letting their receptivity be influenced by naïvety, an over-reliance on common sense, or an unfounded bias against a speaker. Perhaps the development of the virtue argumentation theory approach to fallacies provides a supplement to Mill’s theory of fallacies. He distinguished (1891, V, i, 3) what he called the moral (dispositional) and intellectual causes of fallacy. The study of the argumentative vices envisioned above seems best included under the moral study of fallacies as the vices can be taken to be the presdisposing causes to commit intellectual mistakes, i.e., misevaluations of the weight of evidence.

4. Current issues in fallacy theory

A question that continues to dog fallacy theory is how we are to conceive of fallacies. There would be advantages to having a unified theory of fallacies. It would give us a systematic way of demarcating fallacies and other kinds of mistakes; it would give us a framework for justifying fallacy judgments, and it would give us a sense of the place of fallacies in our larger conceptual schemes. Some general definition of ‘fallacy’ is wanted but the desire is frustrated because there is disagreement about the identity of fallacies. Are they inferential, logical, epistemic or dialectical mistakes? Some authors insist that they are all of one kind: Biro and Siegel, for example, that they are epistemic, and Pragma-dialectics that they are dialectical. There are reasons to think that all fallacies do not easily fit into one category.

Together the Sophistical Refutations and Locke’s Essay are the dual sources of our inheritance of fallacies. However, for four reasons they make for uneasy bedfellows. First, the ad fallacies seem to have a built-in dialectical character, which, it can be argued, Aristotle’s fallacies do not have (they are not sophistical refutations but are in sophistical refutations). Second, Aristotle’s fallacies are logical mistakes: they have no appropriate employment outside eristic argumentation whereas the ad -fallacies are instances of ad -arguments, often appropriately used in dialogues. Third, the appearance condition is part of the Aristotelian inheritance but it is not intimately connected with the ad -fallacies tradition. A fourth reason that contributes to the tension between the Aristotelian and Lockean traditions in fallacies is that the former grew out of philosophical problems, largely what are logical and metaphysical puzzles (consider the many examples in Sophistical Refutations ), whereas the ad -fallacies are more geared to social and political topics of popular concern, the subject matter that most intrigues modern researchers on fallacy theory.

As we look back over our survey we cannot help but observe that fallacies have been identified in relation to some ideal or model of good arguments, good argumentation, or rationality. Aristotle’s fallacies are shortcomings of his ideal of deduction and proof, extended to contexts of refutation. The fallacies listed by Mill are errors of reasoning in a comprehensive model that includes both deduction and induction. Those who have defended SDF as the correct definition of ‘fallacy’ [ 10 ] take logic simpliciter or deductive validity as the ideal of rationality. Informal logicians view fallacies as failures to satisfy the criteria of what they consider to be a cogent argument. Defenders of the epistemic approach to fallacies see them as shortfalls of the standards of knowledge-generating arguments. Finally, those who are concerned with how we are to overcome our disagreements in a reasonable way will see fallacies as failures in relation to ideals of debate or critical discussions.

The standard treatment of the core fallacies has not emerged from a single conception of good argument or reasonableness but rather, like much of our unsystematic knowledge, has grown as a hodgepodge collection of items, proposed at various time and from different perspectives, that continues to draw our attention, even as the standards that originally brought a given fallacy to light are abandoned or absorbed into newer models of rationality. Hence, there is no single conception of good argument or argumentation to be discovered behind the core fallacies, and any attempt to force them all into a single framework, must take efforts to avoid distorting the character originally attributed to each of them.

From Aristotle to Mill the appearance condition was an essential part of the conception of fallacies. However, some of the new, post-Hamblin, scholars have either ignored it (Finocchiaro, Biro and Siegel) or rejected it because appearances can vary from person to person, thus making the same argument a fallacy for the one who is taken in by the appearance, and not a fallacy for the one who sees past the appearances. This is unsatisfactory for those who think that arguments are either fallacies or not. Appearances, it is also argued, have no place in logical or scientific theories because they belong to psychology (van Eemeren and Grootendorst, 2004). But Walton (e.g., 2010) continues to consider appearances an essential part of fallacies as does Powers (1995, 300) who insists that fallacies must “have an appearance, however quickly seen through, of being valid.” If the mistake in an argument is not masked by an ambiguity that makes it appear to be a better argument than it really is, Powers denies it is a fallacy.

The appearance condition of fallacies serves at least two purposes. First, it can be part of explanations of why reasonable people make mistakes in arguments or argumentation: it may be due in part to an argument’s appearing to be better than it really is. Second, it serves to divide mistakes into two groups: those which are trivial or the result of carelessness (for which there is no cure other than paying better attention), and those which we need to learn to detect through an increased awareness of their seductive nature. Without the appearance condition, it can be argued, no division can be made between these two kinds of errors: either there are no fallacies or all mistakes in argument and/or argumentation are fallacies; a conclusion that some are willing to accept, but which runs contrary to tradition. One can also respond that there is an alternative to using the appearance condition as the demarcation property between fallacies and casual mistakes, namely, frequency. Fallacies are those mistakes we must learn to guard against because they occur with noticeable frequency. To this it may be answered that ‘noticeable frequency’ is vague, and is perhaps best explained by the appearance condition.

On the more practical level, there continues to be discussion about the value of teaching the fallacies to students. Is it an effective way for them to learn to reason well and to avoid bad arguments? One reason to think that it is not effective is that the list of fallacies is not complete, and that even if the group of core fallacies was extended to incorporate other fallacies we thought worth including, we could still not be sure that we had a complete prophylactic against bad arguments. Hence, we are better off teaching the positive criteria for good arguments/ argumentation which give us a fuller set of guidelines for good reasoning. But some (Pragma-dialectics and Johnson and Blair) do think that their stock of fallacies is a complete guard against errors because they have specified a full set of necessary conditions for good arguments/argumentation and they hold that fallacies are just failures to meet one of these conditions.

Another consideration about the value of the fallacies approach to teaching good reasoning is that it tends to make students overly critical and lead them to see fallacies where there are not any; hence, it is maintained we could better advance the instilling of critical thinking skills by teaching the positive criteria of good reasoning and arguments (Hitchcock, 1995). In response to this view, it is argued that, if the fallacies are taught in a non-perfunctory way which includes the explanations of why they are fallacies—which normative standards they transgress—then a course taught around the core fallacies can be effective in instilling good reasoning skills (Blair 1995).

Recently there has been renewed interest in how biases are related to fallacies. Correia (2011) has taken Mill’s insight that biases are predisposing causes of fallacies a step further by connecting identifiable biases with particular fallacies. Biases can influence the unintentional committing of fallacies even where there is no intent to be deceptive, he observes. Taking biases to be “systematic errors that invariably distort the subject’s reasoning and judgment,” the picture drawn is that particular biases are activated by desires and emotions (motivated reasoning) and once they are in play, they negatively affect the fair evaluation of evidence. Thus, for example, the “focussing illusion” bias inclines a person to focus on just a part of the evidence available, ignoring or denying evidence that might lead in another direction. Correia (2011, 118) links this bias to the fallacies of hasty generalization and straw man, suggesting that it is our desire to be right that activates the bias to focus more on positive or negative evidence, as the case may be. Other biases he links to other fallacies.

Thagard (2011) is more concerned to stress the differences between fallacies and biases than to find connections between them. He claims that the model of reasoning articulated by informal logic is not a good fit with the way that people actually reason and that only a few of the fallacies are relevant to the kinds of mistakes people actually make. Thagard’s argument depends on his distinction between argument and inference. Arguments, and fallacies, he takes to be serial and linguistic, but inferences are brain activities and are characterized as parallel and multi-modal. By “parallel” is meant that the brain carries out different processes simultaneously, and by “multi-modal” that the brain uses non-linguistic and emotional, as well as linguistic representations in inferring. Biases (inferential error tendencies) can unconsciously affect inferring. “Motivated inference,” for example, “involves selective recruitment and assessment of evidence based on unconscious processes that are driven by emotional considerations of goals rather than purely cognitive reasoning” (2011, 156). Thagard volunteers a list of more than fifty of these inferential error tendencies. Because motivated inferences result from unconscious mental processes rather than explicit reasoning, the errors in inferences cannot be exposed simply by identifying a fallacy in a reconstructed argument. Dealing with biases requires identification of both conscious and unconscious goals of arguers, goals that can figure in explanations of why they incline to particular biases. “Overcoming people’s motivated inferences,” Thagard concludes, “is therefore more akin to psychotherapy than informal logic” (157), and the importance of fallacies is accordingly marginalized.

In response to these findings, one can admit their relevance to the pedagogy of critical thinking but still recall the distinction between what causes mistakes and what the mistakes are. The analysis of fallacies belongs to the normative study of arguments and argumentation, and to give an account of what the fallacy in a given argument is will involve making reference to some norm of argumentation. It will be an explanation of what the mistake in the argument is. Biases are relevant to understanding why people commit fallacies, and how we are to help them get past them, but they do not help us understand what the fallacy-mistakes are in the first place—this is not a question of psychology. Continued research at this intersection of interests will hopefully shed more light on both biases and fallacies.

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How to cite this entry . Preview the PDF version of this entry at the Friends of the SEP Society . Look up topics and thinkers related to this entry at the Internet Philosophy Ontology Project (InPhO). Enhanced bibliography for this entry at PhilPapers , with links to its database.

• Curtis, Gary N., Fallacy Files
• Dowden, Bradley, Fallacies , entry in the Internet Encyclopedia of Philosophy .
• Hansen, H.V., and C. Fioret, 2016. A searchable bibliography of fallacies—2016 , Informal Logic , 36: 432–72.
• Informal Logic , an open-access journal.
• Labossiere, Michael C., Fallacies , hosted by The Nizkor Project.
• RAIL , a blog about Reasoning, Argumentation, and Informal Logic.

logic: informal | relativism

Acknowledgments

The author would like to thank the executive and subject editors who suggested a way to improve the discussion of begging the question .

Copyright © 2020 by Hans Hansen < hhansen @ uwindsor . ca >

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5 Chapter 5 (Logical Fallacies)

Logical Fallacies

What does it mean to say that an argument contains a logical fallacy? Simply put, a logical fallacy is an error in reasoning. While most people try to be reasonable, there are a number of ways that humans frequently make errors in judgment. Looking for logical fallacies is an excellent way of evaluating the rigor of a source. Avoiding logical fallacies in academic writing is also important to make sure that the work that is submitted is reflective of a critical and informed thought process. Note that most people–including academics and researchers–are prone to errors in reasoning. Therefore, it’s important to always evaluate logical progressions, even (or especially) when we agree with the conclusions.

Argument from anecdote

The anecdotal fallacy is when someone uses personal experience or an isolated example as a means of proving a point (or of discrediting a related point). One reason people are vulnerable to the anecdotal fallacy is that narratives and personal experiences can feel more “real” than numbers or statistics. For example, if a study says that a particular car manufacturer is more likely to have safety problems then a competitor (e.g. 200 problems per 1000 vehicles compared to 50 problems per 1000 vehicles), those numbers are less emotionally powerful than my personal experience with a car made by that manufacturer, that I owned for 10 years “without a problem.” Unfortunately, those stories don’t actually make the favored manufacturer safer. They just mean that the car I owned was fine—perhaps because it was never placed in a situation where the safety concerns were an issue.

This does not mean that a source is flawed as soon as it uses narrative or example. What it means is that a narrative or example does not prove anything. It doesn’t even really do much to support something. However, a narrative or example can do a great job of explaining or of illustrating something.

What’s the difference?

The difference is in terms of how the narrative is being used. Imagine an argument that involves deciding whether or not someone should eat crunchy vegetables as part of a healthy diet. A story about a man who choked on a carrot and died does not prove that eating crunchy vegetables is more dangerous than the alternative. However, if I have already established that crunchy vegetables are rich in fiber, and that fiber is part of a healthy diet, then a story about a man who suffered from digestion problems until he added crunchy vegetables is not proving anything. It is putting a human face on a point that has already been made.

In crude terms, the story never proves the point. Instead, the point must be proven with actual evidence, and that evidence can then be supported with an example that shows the process or event in action. Students conducting research need to be wary of sources that use examples or individual stories to “prove” things instead of proving the point through other means and then adding stories as well.

Proof in this case would need to include all of the same basic components of any chain or argument. First, is what we think we are seeing really there? In other words, when people start eating crunchy vegetables, do we know that it’s the vegetables that are providing the benefit or is it something else (for example, just the act of thinking about being healthier).

One way to examine this is to see what happens if people think about being healthier and are given non-crunchy vegetables to eat (but are told they are healthy) while other people of the same age and general health are given crunchy vegetables to eat. Over enough time and with enough difference in results, it becomes reasonable to say that the vegetables (or the belief) are involved in the difference.

Note that the experiment described above helps to answer a second question—and that is the question of which is the cause and which is the effect? Assume for the moment that there is in fact some sort of correlation between eating crunchy vegetables and being healthier. Let’s imagine that we have noticed a trend in people in general, in that the people who eat crunchy vegetables are only half as likely to get certain diseases as people who do not. Great! Does that prove that eating crunchy vegetables is healthy? It does not. Why not? Because we still need to determine whether or not being healthy makes people crave crunchy vegetables, or if eating the crunchy vegetables actually causes being healthy. Actually, it’s more complicated than this, because the correlation could be coincidence (it just sort of happened) or it could be caused by a third factor (people who are well-off enough to have access to fresh and crunchy vegetables might also have access to other things that make them healthy, like fresh air and enough free time to exercise).

What this means is that any story, true or hypothetical, is typically only useful in explaining what other, more objective, evidence shows. However, stories can be really good at providing that kind of explanation!

The Ad Populum Fallacy

C oming from the Latin for “to the people” (and sometimes called the bandwagon fallacy), this fallacy involves thinking that because an idea is popular or believed by many that the idea must be valid. In arguments, it frequently manifests as assuming that a point does not need to be proven or established because “everyone knows” it is true already. Another version is that the more popular idea is inherently “better” than the less popular idea. Reality, however, is not democratic in nature. Consider the once widespread belief that “people only use 10% of their brain”, which alleges that most people have vast reserves of intellectual capacity that go unfilled. This single misconception has been used to justify a number of other beliefs and suppositions. However, there is very little evidence to support it and a significant amount of evidence to contradict it.

Someone appealing to the belief that “everyone knows we only use 10% of our brain” is actually beginning from a flawed position. Not only are there a number of people who know better than to believe this falsehood, the fact that people believe it does not make it true.

This creates a very tricky balancing act. First, someone engaging in argument needs to be sure that they use sources that do not make assumptions based on what “everyone knows,” but it is often difficult to sort out what needs to be proven and what can be assumed for the sake of efficiency. For example, even very basic neurology texts do not bother to explain how the authors know that human beings have brains. The simple test is whether or not support is at least available on demand, and whether or not that support is independent of the opinions or beliefs of individuals. A more complex test is whether or not the argument in question depends on the assumption.

If an argument talks about psychic powers being potentially real because they tap into the “unused 90%” of the brain, then that argument depends upon the belief that a significant portion of the brain goes unused. On the other hand, if an argument talks about how people learn new languages and it references the existence of brains, but the data is present to show that languages really are acquired in a consistent fashion, then it no longer really matters (for this argument and only for this argument) if the organ doing the learning is the brain or the heart (and indeed, once upon a time, many people did believe that thinking took place in the heart—they were no more right then than they would be now-belief doesn’t make it real).

Correlation Fallacy

One consistent mistake people make is seeing that two events occur in proximity to one another and then trying to associate them by saying that one caused the other. Because this is sometimes the case, it can be easy for researchers to trick themselves into thinking that it is always the case. However, correlation does not mean causation, and oftentimes the cause can be mistaken for the effect, the cause and effect can both be effects of a third factor, or they can simply be unrelated phenomena.

Take for example the age-old adage in American football that teams that run the ball more often are likely to win. Even if this turned out to be true, statistically, that fact does not tell us whether teams that are winning run the ball in order to slow down the game (and thereby preserve their lead) or whether running the ball helped them get the lead (thereby demonstrating a usable strategy). Which is the cause and which is the effect? As has been pointed out by the statistical analysis organization Football Outsiders multiple times, the actual data supports the trend or running to protect a lead, not running to create a lead. In fact, as has been pointed out, two or more instances in a row of a quarterback kneeling with the football has a higher correlation with winning that running, but few people would suggest kneeling to win. Why? Because here it is more obvious which is the cause and which is the effect.

However, many people will observe an event and assume that the event causes things that come afterward (this is a specific fallacy called Post Hoc, Ergo Propter Hoc —after the thing, therefore because of the thing). One of the original arguments made to allege the (completely disproven) link between autism and MMR vaccines was note that autism rates seemed to increase as vaccination rates increased. Even beyond biological and chemical flaws with these claims, purely numeric problems with this misuse of statistics were how it ignored the simultaneous increase in efforts to correctly identify autism (in other words, rates didn’t go up, but tracking improved) and the fact that when vaccination rates later fell autism rates continued to climb.

A good way of examining whether or not an event is causing other events is by looking for controls on the effect (natural or artificial) and looking for mechanisms of action. What does this mean? The first means that cause-and-effect can be evaluated if one is absent and the other still happens. If autism rates climb (or hold steady) even as vaccination rates decline, then it seems unlikely that the MMR vaccine is causing the increase. Likewise, autism rates hold steady (or go down) as vaccination rates increase, that also creates a disconnect.

The second crosscheck is trickier, and it again requires that researchers understand what they are looking at. Is there a reasonable explanation for how the supposed cause could actually create the supposed effect? In the case of the MMR vaccination issue, an uneducated person might believe this was the case—some versions of the vaccine used a form of mercury as a preservative, and some forms of mercury had been shown to have neurological effects on people.

However, there are a number of problems with this explanation. First, not all versions of the MMR vaccine had this preservative, and the data for autism rates were roughly the same where the preservative was used and where it was not. Second, the form of mercury used in the vaccines was not the same form of mercury that had the neurological effects in question. Third, the types of neurological effects associated with mercury are not similar to autism. There are other, technical, issues as well (such as the absence of lingering mercury poisoning in the subjects who were studied). In short, knowing even a little bit more about the subject does much to undermine the connection.

However, a simple search engine quest will still reveal a number of people who repeat the disproven, logically unsound argument.

The Middle Ground Fallacy

Many people have a very well-meaning impulse to seek compromise and to try to be “fair,” claiming that everyone might have a valid point. Unfortunately, this reflex is very easy to manipulate. Worse, it is grounded in an emotional reaction and not in evidence. To some extent, it depends upon the bandwagon/ad populum fallacy. Essentially, the middle ground fallacy assumes that if two (or more) people have differing opinions, then each of them must have at least some validity to their points. Therefore, the “right” answer must involve compromise.

Imagine that some people believe that the pyramids of Egypt were created by architects and laborers thousands of years ago using a combination of engineering principles and hard work, building off of the earlier burial structures known as mastabas . Now imagine that other people believe that the same pyramids were made without local predecessors by extraterrestrials using antigravity technology. The middle ground fallacy would suggest that some pyramids were made by aliens, or perhaps that aliens made the mastabas and then left behind their antigravity devices so the locals could figure out pyramids on their own.

While this example is (hopefully) laughable, trickier examples exist. In fact, canny manipulators can end up presenting their own viewpoints as the compromise. If I want college tuition to stay the same as is currently is, all I need to do is find someone arguing that tuition needs to be raised and someone else saying that it needs to be lowered. I then present my “fair” compromise of keeping it constant!

Sources that commit the middle ground fallacy frequently do so by having incomplete support for one of the two extreme positions, arguing that simply finding people who believe those positions is actually enough of a reason to offer a compromise (and for why this doesn’t hold up, see the earlier section on ad populum ). Instead of compromise, a strong argument should actually present evidence in support of its position, and countervailing evidence should actually be put into context.

Consider the pyramids example. There is strong archaeological, historical, and cultural evidence in support of the “architects and laborers” origin of these works. There is nothing resembling the evidence for the “extraterrestrials and antigravity” explanation. There is therefore no need for compromise.

Observational Selection

The fallacy of only counting the examples that support your position and ignoring the rest. This fallacy is also known as card-stacking, cherry-picking, and the fallacy of exclusion, this is a fallacy because it does not take into consideration all (or even most) of the data. The classic illustration is how believers in astrology frequently count the times that a horoscope or other prediction seems to turn out “right” as evidence in the favor of astrology while ignoring the other predictions that did not work out as evidence against astrology.

In student writing, an equivalent might be a pro-gun rights paper where a student mentions the number of times citizens with guns stop violent crimes while ignoring the violent crimes committed by citizens with guns.

One of the easiest ways for sources to cherry-pick data is to offer numbers or stories without context. If my friend tells me that he tripled the number of books he went on from one year to the next, that doesn’t tell me if he added two books (from one to three) or if he added twenty (from ten to thirty).

Research, Evidence, and Written Arguments Copyright © by jsunderb. All Rights Reserved.

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Unit 6: Argumentative Essay Writing

47 Logical Fallacies

Logical fallacies are errors in reasoning based on faulty logic . Good writers want to convince readers to agree with their arguments—their reasons and conclusions. If your arguments are not logical, readers won’t be convinced. Logic can help prove your point and disprove your opponent’s point—and perhaps change a reader’s mind about an issue. If you use faulty logic (logic not based on fact), readers will not believe you or take your position seriously.

Read about five of the most common logical fallacies and how to avoid them below:

• Generalizations
• Loaded words
• Inappropriate authority figures
• Either/or arguments
• Slippery slope

Common Logical Fallacies

Below are five of the most common logical fallacies.

#1 Generalizations

Explanation: Hasty generalizations are just what they sound like—making quick judgments based on inadequate information. This kind of logical fallacy is a common error in argumentative writing.

Example 1: Ren didn’t want to study at a university. Instead, Ren decided to go to a technical school. Ren is now making an excellent salary repairing computers. Luis doesn’t want to study at a university. Therefore, Luis should go to a technical school to become financially successful.

Analysis: While they have something in common (they both want to go to school and earn a high salary), this fact alone does not mean Luis would be successful doing the same thing that their friend Ren did. There may be other specific information which is important as well, such as the fact that Ren has lots of experience with computers or that Luis has different skills.

Example 2: If any kind of gun control laws are enacted, citizens will not be allowed to have any guns at all.

Analysis: While passing new gun control laws may result in new restrictions, it is highly unlikely the consequences would be so extreme; gun control is a complex issue and each law that may be passed would have different outcomes. Words such as “all,” “always,” “never,” “everyone,” “at all” are problematic because they cannot be supported with evidence. Consider making less sweeping and more modest conclusions.

Suggestions for Avoiding Generalizations

Replace “absolute” expressions with more “softening” expressions.

• Replace words like “all” or “everyone” with “most people.” Instead of “no one” use “few people.”
• Replace “always” with “typically” or “usually” or “often.”
• Replace “never” with “rarely” or “infrequently” or the “to be verb” + “unlikely.”
• Replace “will” with “may or might or could” or use the “to be verb” + “likely.”

Example 1 revised: Luis could consider going to a technical school. This education track is more likely to lead to financial success.

Example 2 revised: If extensive gun control laws are enacted, some citizens may feel their constitutional rights are being limited.

#2 Loaded Words

Explanation: Some words contain positive or negative connotations, which may elicit a positive or negative emotional response. Try to avoid them in academic writing when making an argument because your arguments should be based on reason (facts and evidence), not emotions.  In fact, using these types of words may cause your reader to react against you as the writer, rather than being convincing as you hoped.  Therefore they can make your argument actually weaker rather than stronger.

Example 1: It is widely accepted by reasonable people that free-trade has a positive effect on living standards, although some people ignorantly disagree with this.

Analysis: The words “reasonable” (positive) and “ignorantly” (negative) may bias the readers about the two groups without giving any evidence to support this bias.

Example 2: This decision is outrageous and has seriously jeopardized the financial futures for the majority of innocent citizens.

Analysis: The words “outrageous,” “seriously,” and “innocent” appeal to readers’ emotions in order to persuade them more easily. However, the most persuasive arguments in academic writing will be supported with evidence instead of drawing on emotions.

Suggestions for Avoiding Loaded Words

Choose appropriate vocabulary.

• Omit adjectives and adverbs, especially if they carry emotion, value, or judgment.
• Replace/add softeners like, “potentially” or modals like “might” or “may.”

Example 1 revised: It is widely accepted by many people that free-trade may have a positive effect on living standards, although some people may disagree with this.

Example 2 revised: This decision has potentially serious consequences for the financial futures for the majority of citizens.

#3 Inappropriate authority figures

Explanation: Using famous names may or may not help you prove your point. However, be sure to use the name logically and in relation to their own area of authority.

Example 1: Albert Einstein , one of the fathers of atomic energy, was a vegetarian and believed that animals deserved to be treated fairly. In short, animal testing should be banned.

Analysis: While Einstein is widely considered one of the great minds of the 20th century, he was a physicist , not an expert in animal welfare or ethics.

Example 2: Nuclear power is claimed to be safe because there is very little chance for an accident to happen, but little chance does not have the same meaning as safety. Riccio (2013), a news reporter for the Wisconsin State Journal, holds a strong opinion against the use of nuclear energy and constructions of nuclear power plants because he believes that the safety features do not meet the latest standards.

Analysis: In order to provide strong evidence to support the claim regarding the safety features of nuclear power plants, expert opinion is needed ; the profession of a reporter does not provide sufficient expertise to validate the claim.

Suggestions for Avoiding Inappropriate Authority Figures

Replace inappropriate authority figures with credible experts.

• Read through your sources and look for examples of experts. Pay attention to their credentials. (See examples below.)
• Find new sources written by or citing legitimate experts in the field.
• Google the authority figure you wish to use to determine if they are an expert in the field. Use the Library Databases to locate a substantive or scholarly article related to your topic. Cite the author of one of these articles or use an indirect citation to cite an expert mentioned in the article.

Example 1 revised: Kitty Block, president and CEO of the Humane Society of the U.S. , emphasizes the need for researchers to work with international governments and agencies to follow new guidelines to protect animals and minimize their use in animal testing.

Example 2 revised: Edwin Lyman, senior scientist of the Global Security Program, points out that while the U.S. has severe-accident management programs, these plans are not evaluated by the Nuclear Regulatory Commission, and therefore may be subject to accidents or sabotage.

#4 Either/Or Arguments

Explanation: When you argue a point, be careful not to limit the choices to only two or three. This needs to be qualified.

Example 1: Studying abroad either increases job opportunities or causes students to become depressed.

Analysis: This statement implies that only two things may happen, whereas in reality these are two among many possible outcomes.

Example 2: People can continue to spend countless amounts of tax dollars fighting the use of a relatively safe drug, or they can make a change, legalize marijuana, and actually see a tax and revenue benefit for our state. (owl.excels ior.edu)

Analysis: Most issues are very complex and hardly ever either/or, i.e. they rarely have only two opposing ways of looking at them or two possible outcomes. Instead, use language that acknowledges the complexity of the issue.

Suggestions for Avoiding Either/Or Arguments

Offer more than one or two choices, options, or outcomes.

• If relevant for your essay focus, offer more than one or two choices, options, or outcomes.
• Acknowledge that multiple outcomes or perspectives exist.

Example 1 revised: Studying abroad may have a wide spectrum of outcomes , both positive and negative, from increasing job opportunities to leading to financial debt and depression.

Example 2 revised: There are a number of solutions for mitigating the illegal sale of marijuana, including legalizing the use of the drug in a wider range of contexts, increasing education about the drug and its use, and creating legal businesses for the sale, among other business related solutions.

#5 Slippery Slope

Explanation: When you argue that a chain reaction will take place, i.e. say that one problem may lead to a greater problem, which in turn leads to a greater problem, often ending in serious consequences. This way of arguing exaggerates and distorts the effects of the original choice. If the series of events is extremely improbable, your arguments will not be taken seriously.

Example 1: Animal experimentation reduces society’s respect for life. If people don’t respect life, they are likely to be more and more tolerant of violent acts like war and murder. Soon society will become a battlefield in which everyone constantly fears for their lives.

Analysis: This statement implies that allowing animal testing shows a moral problem which can lead to completely different, greater outcomes: war, death, the end of the world!  Clearly an exaggeration.

Example 2: If stricter gun control laws are enacted, the right of citizens to own guns may be greatly restricted, which may limit their ability to defend themselves against terrorist attacks. When that happens, the number of terrorist attacks in this country may increase. Therefore, gun control laws may result in higher probability of widespread terrorism. (owl.excelsior.edu)

Analysis: The issue of gun control is exaggerated to lead into a very different issue. Check your arguments to make sure any chains of consequences are reasonable and still within the scope of your focused topic. (writingcenter.unc.edu)

Suggestions for Avoiding Slippery Slope

Think through the chain of events.

• Carefully think about the chain of events and know when to stop to make sure these events are still within the narrowed focus of your essay.

Example 1 revised: If animal experimentation is not limited, an increasing number of animals will likely continue to be hurt or killed as a result of these experiments.

Example 2 revised: With stricter gun laws, the number of citizens who are able to obtain firearms may be reduced, which could lead to fewer deaths involving guns.

As you read your own work, imagine you are reading the draft for the first time. Look carefully for any instances of faulty logic and then use the tips above to eliminate the logical fallacies in your writing.

Adapted from Great Essays by Folse, Muchmore-Vokoun, & Soloman

For more logical fallacies, watch this video.

from GCFLearnFree.org

Academic Writing I Copyright © by UW-Madison ESL Program is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License , except where otherwise noted.

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• How to write an argumentative essay | Examples & tips

How to Write an Argumentative Essay | Examples & Tips

Published on July 24, 2020 by Jack Caulfield . Revised on July 23, 2023.

An argumentative essay expresses an extended argument for a particular thesis statement . The author takes a clearly defined stance on their subject and builds up an evidence-based case for it.

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Table of contents

When do you write an argumentative essay, approaches to argumentative essays, introducing your argument, the body: developing your argument, concluding your argument, other interesting articles, frequently asked questions about argumentative essays.

You might be assigned an argumentative essay as a writing exercise in high school or in a composition class. The prompt will often ask you to argue for one of two positions, and may include terms like “argue” or “argument.” It will frequently take the form of a question.

The prompt may also be more open-ended in terms of the possible arguments you could make.

Argumentative writing at college level

At university, the vast majority of essays or papers you write will involve some form of argumentation. For example, both rhetorical analysis and literary analysis essays involve making arguments about texts.

In this context, you won’t necessarily be told to write an argumentative essay—but making an evidence-based argument is an essential goal of most academic writing, and this should be your default approach unless you’re told otherwise.

Examples of argumentative essay prompts

At a university level, all the prompts below imply an argumentative essay as the appropriate response.

Your research should lead you to develop a specific position on the topic. The essay then argues for that position and aims to convince the reader by presenting your evidence, evaluation and analysis.

• Don’t just list all the effects you can think of.
• Do develop a focused argument about the overall effect and why it matters, backed up by evidence from sources.
• Don’t just provide a selection of data on the measures’ effectiveness.
• Do build up your own argument about which kinds of measures have been most or least effective, and why.
• Don’t just analyze a random selection of doppelgänger characters.
• Do form an argument about specific texts, comparing and contrasting how they express their thematic concerns through doppelgänger characters.

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An argumentative essay should be objective in its approach; your arguments should rely on logic and evidence, not on exaggeration or appeals to emotion.

There are many possible approaches to argumentative essays, but there are two common models that can help you start outlining your arguments: The Toulmin model and the Rogerian model.

Toulmin arguments

The Toulmin model consists of four steps, which may be repeated as many times as necessary for the argument:

• Make a claim
• Provide the grounds (evidence) for the claim
• Explain the warrant (how the grounds support the claim)
• Discuss possible rebuttals to the claim, identifying the limits of the argument and showing that you have considered alternative perspectives

The Toulmin model is a common approach in academic essays. You don’t have to use these specific terms (grounds, warrants, rebuttals), but establishing a clear connection between your claims and the evidence supporting them is crucial in an argumentative essay.

Say you’re making an argument about the effectiveness of workplace anti-discrimination measures. You might:

• Claim that unconscious bias training does not have the desired results, and resources would be better spent on other approaches
• Cite data to support your claim
• Explain how the data indicates that the method is ineffective
• Anticipate objections to your claim based on other data, indicating whether these objections are valid, and if not, why not.

Rogerian arguments

The Rogerian model also consists of four steps you might repeat throughout your essay:

• Discuss what the opposing position gets right and why people might hold this position
• Highlight the problems with this position
• Present your own position , showing how it addresses these problems
• Suggest a possible compromise —what elements of your position would proponents of the opposing position benefit from adopting?

This model builds up a clear picture of both sides of an argument and seeks a compromise. It is particularly useful when people tend to disagree strongly on the issue discussed, allowing you to approach opposing arguments in good faith.

Say you want to argue that the internet has had a positive impact on education. You might:

• Acknowledge that students rely too much on websites like Wikipedia
• Argue that teachers view Wikipedia as more unreliable than it really is
• Suggest that Wikipedia’s system of citations can actually teach students about referencing
• Suggest critical engagement with Wikipedia as a possible assignment for teachers who are skeptical of its usefulness.

You don’t necessarily have to pick one of these models—you may even use elements of both in different parts of your essay—but it’s worth considering them if you struggle to structure your arguments.

Regardless of which approach you take, your essay should always be structured using an introduction , a body , and a conclusion .

Like other academic essays, an argumentative essay begins with an introduction . The introduction serves to capture the reader’s interest, provide background information, present your thesis statement , and (in longer essays) to summarize the structure of the body.

Hover over different parts of the example below to see how a typical introduction works.

The spread of the internet has had a world-changing effect, not least on the world of education. The use of the internet in academic contexts is on the rise, and its role in learning is hotly debated. For many teachers who did not grow up with this technology, its effects seem alarming and potentially harmful. This concern, while understandable, is misguided. The negatives of internet use are outweighed by its critical benefits for students and educators—as a uniquely comprehensive and accessible information source; a means of exposure to and engagement with different perspectives; and a highly flexible learning environment.

The body of an argumentative essay is where you develop your arguments in detail. Here you’ll present evidence, analysis, and reasoning to convince the reader that your thesis statement is true.

In the standard five-paragraph format for short essays, the body takes up three of your five paragraphs. In longer essays, it will be more paragraphs, and might be divided into sections with headings.

Each paragraph covers its own topic, introduced with a topic sentence . Each of these topics must contribute to your overall argument; don’t include irrelevant information.

This example paragraph takes a Rogerian approach: It first acknowledges the merits of the opposing position and then highlights problems with that position.

Hover over different parts of the example to see how a body paragraph is constructed.

A common frustration for teachers is students’ use of Wikipedia as a source in their writing. Its prevalence among students is not exaggerated; a survey found that the vast majority of the students surveyed used Wikipedia (Head & Eisenberg, 2010). An article in The Guardian stresses a common objection to its use: “a reliance on Wikipedia can discourage students from engaging with genuine academic writing” (Coomer, 2013). Teachers are clearly not mistaken in viewing Wikipedia usage as ubiquitous among their students; but the claim that it discourages engagement with academic sources requires further investigation. This point is treated as self-evident by many teachers, but Wikipedia itself explicitly encourages students to look into other sources. Its articles often provide references to academic publications and include warning notes where citations are missing; the site’s own guidelines for research make clear that it should be used as a starting point, emphasizing that users should always “read the references and check whether they really do support what the article says” (“Wikipedia:Researching with Wikipedia,” 2020). Indeed, for many students, Wikipedia is their first encounter with the concepts of citation and referencing. The use of Wikipedia therefore has a positive side that merits deeper consideration than it often receives.

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An argumentative essay ends with a conclusion that summarizes and reflects on the arguments made in the body.

No new arguments or evidence appear here, but in longer essays you may discuss the strengths and weaknesses of your argument and suggest topics for future research. In all conclusions, you should stress the relevance and importance of your argument.

Hover over the following example to see the typical elements of a conclusion.

The internet has had a major positive impact on the world of education; occasional pitfalls aside, its value is evident in numerous applications. The future of teaching lies in the possibilities the internet opens up for communication, research, and interactivity. As the popularity of distance learning shows, students value the flexibility and accessibility offered by digital education, and educators should fully embrace these advantages. The internet’s dangers, real and imaginary, have been documented exhaustively by skeptics, but the internet is here to stay; it is time to focus seriously on its potential for good.

If you want to know more about AI tools , college essays , or fallacies make sure to check out some of our other articles with explanations and examples or go directly to our tools!

• Ad hominem fallacy
• Post hoc fallacy
• Appeal to authority fallacy
• False cause fallacy
• Sunk cost fallacy

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An argumentative essay tends to be a longer essay involving independent research, and aims to make an original argument about a topic. Its thesis statement makes a contentious claim that must be supported in an objective, evidence-based way.

An expository essay also aims to be objective, but it doesn’t have to make an original argument. Rather, it aims to explain something (e.g., a process or idea) in a clear, concise way. Expository essays are often shorter assignments and rely less on research.

At college level, you must properly cite your sources in all essays , research papers , and other academic texts (except exams and in-class exercises).

Add a citation whenever you quote , paraphrase , or summarize information or ideas from a source. You should also give full source details in a bibliography or reference list at the end of your text.

The exact format of your citations depends on which citation style you are instructed to use. The most common styles are APA , MLA , and Chicago .

The majority of the essays written at university are some sort of argumentative essay . Unless otherwise specified, you can assume that the goal of any essay you’re asked to write is argumentative: To convince the reader of your position using evidence and reasoning.

In composition classes you might be given assignments that specifically test your ability to write an argumentative essay. Look out for prompts including instructions like “argue,” “assess,” or “discuss” to see if this is the goal.

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