Logical Fallacies and the Art of Debate

1 Logical 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.” – UNC Writing Center  Ad Hominem (personal attack) - An Ad Hominem is a general category of fallacies in which a claim or argument is rejected on the basis of some irrelevant fact about the author of or the person presenting the claim or argument. Typically, this fallacy involves two steps. First, an attack against the character of person making the claim, her circumstances, or her actions is made (or the character, circumstances, or actions of the person reporting the claim). Second, this attack is taken to be evidence against the claim or argument the person in question is making (or presenting). Ad populum (appeal to popularity) - The Latin name of this fallacy means “to the people.” There are several versions of the ad populum fallacy, but what they all have in common is that in 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 his or her 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.  Fallacious Appeal to Authority - (questionable authority) An Appeal to Authority is a fallacy with the following form: Person A is (claimed to be) an authority on subject S. 2 Person A makes claim C about subject S. Therefore, C is true. This fallacy is committed when the person in question is not a legitimate authority on the subject. More formally, if person A is not qualified to make reliable claims in subject S, then the argument will be fallacious.  Fallacious Appeal to Emotion - An Appeal to Emotion is a fallacy with the following structure: Favorable emotions are associated with X. Therefore, X is true. This fallacy is committed when someone manipulates peoples' emotions in order to get them to accept a claim as being true. More formally, this sort of "reasoning" involves the substitution of various means of producing strong emotions in place of evidence for a claim. If the favorable emotions associated with X influence the person to accept X as true because they "feel good about X," then he has fallen prey to the fallacy. This sort of "reasoning" is very common in politics and it serves as the basis for a large portion of modern advertising. Most political speeches are aimed at generating feelings in people so that these feelings will get them to vote or act a certain way. In the case of advertising, the commercials are aimed at evoking emotions that will influence people to buy certain products. In most cases, such speeches and commercials are notoriously free of real evidence.  Appeal to Fear (scare tactics) - The Appeal to Fear is a fallacy with the following pattern: Y is presented (a claim that is intended to produce fear). Therefore claim X is true (a claim that is generally, but need not be, related to Y in some manner). This line of "reasoning" is fallacious because creating fear in people does not constitute evidence for a claim. It is important to distinguish between a rational reason to believe (RRB) (evidence) and a prudential reason to believe (PRB) (motivation). A RRB is evidence that objectively and logically supports the claim. A PRB is a reason to accept the belief because of some external factor (such as fear, a threat, or a benefit or harm that may stem from the belief) that is relevant to what a person values but is not relevant to the truth or falsity of the claim. For example, it might be prudent to not fail the son of your department chairperson because you fear he will make life tough for you. However, this does not provide evidence for the claim that the son deserves to pass the class. 3  Appeal to Flattery - An Appeal to Flattery is a fallacy of the following form: Person A is flattered by person B. Person B makes claim X. Therefore X is true. The basic idea behind this fallacy is that flattery is presented in the place of evidence for accepting a claim. this sort of "reasoning" is fallacious because flattery is not, in fact, evidence for a claim. This is especially clear in a case like this: "My Bill, that is a really nice tie. By the way, it is quite clear that one plus one is equal to forty three." Appeal to Ignorance - 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.” “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. – UNC Writing Center  Falacious Appeal to Tradition - This sort of "reasoning" is fallacious because the age of something does not automatically make it correct or better than something newer. This is made quite obvious by the following example: The theory that witches and demons cause disease is far older than the theory that microrganisms cause diseases. Therefore, the theory about witches and demons must be true. Obviously, age does have a bearing in some contexts. For example, if a person concluded that aged wine would be better than brand new wine, he would not be committing an Appeal to Tradition. This is because, in such cases the age of the thing is relevant to its quality. Thus, the fallacy is committed only when the age is not, in and of itself, relevant to the claim. One final issue that must be considered is the "test of time." In some cases people might be assuming that because something has lasted as a tradition or has been around a long time that it is true because it has "passed the test of time." If a person assumes that something must be correct or true simply because it has persisted a long time, then he has committed an Appeal to Tradition. After all, as history has shown people can persist in accepting false claims for centuries. 4  Bandwagon - The Bandwagon is a fallacy in which a threat of rejection by one's peers (or peer pressure) is substituted for evidence in an "argument." This line of "reasoning" has the following form: Person P is pressured by his/her peers or threatened with rejection. Therefore person P's claim X is false. This line of "reasoning" is fallacious because peer pressure and threat of rejection do not constitute evidence for rejecting a claim. This is expecially clear in the following example: Joe: "Bill, I know you think that 1+1=2. But we don't accept that sort of thing in our group. " Bill: "I was just joking. Of course I don't believe that." It is clear that the pressure from Bill's group has no bearing on the truth of the claim that 1+1=2.  Begging the Question Begging the Question is a fallacy in which the premises include the claim that the conclusion is true or (directly or indirectly) assume that the conclusion is true. This sort of "reasoning" typically has the following form. Premises in which the truth of the conclusion is claimed or the truth of the conclusion is assumed (either directly or indirectly). Claim C (the conclusion) is true. This sort of "reasoning" is fallacious because simply assuming that the conclusion is true (directly or indirectly) in the premises does not constitute evidence for that conclusion. Obviously, simply assuming a claim is true does not serve as evidence for that claim. This is especially clear in particularly blatant cases: "X is true. The evidence for this claim is that X is true." Some cases of question begging are fairly blatant, while others can be extremely subtle. 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 5 acceptable; instead, she has left us asking “well, really, why do you think active euthanasia is acceptable?” Her 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.  False Dichotomy (false dilemma) – This fallacy contends that “There is no middle ground” and is sometimes known as “black and white thinking.” A False Dilemma is a fallacy in which a person uses the following pattern of "reasoning": Either claim X is true or claim Y is true (when X and Y could both be false). Claim Y is false. Therefore claim X is true  Guilt By Association Guilt by Association is a fallacy in which a person rejects a claim simply because it is pointed out that people she dislikes accept the claim. This sort of "reasoning" has the following form: It is pointed out that people person A does not like accept claim P. Therefore P is false  Hasty Generalization (aka hasty induction) This fallacy is committed when a person draws a conclusion about a population based on a sample that is not large enough. For example, two students are talking: “You can’t speak Italian, and neither can I. I guess no one at this school speaks Italian.”  Poisoning the Well This sort of "reasoning" involves trying to discredit what a person might later claim by presenting unfavorable information (be it true or false) about the person. This "argument" has the following form: 6 Unfavorable information (be it true or false) about person A is presented. Therefore any claims person A makes will be false. Example: Political candidate Fred finishes his stump speech with these lines before his opponent takes the stage: “My opponent is known to misrepresent the truth. Let’s hear what he has to say about the campaign.” Missing the Point (non sequitur): The premises of an argument support a particular conclusion but not the conclusion that the arguer actually draws. No sequitur in Latin means “does not follow,” as in the conclusion does not follow logically from the premises. • 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.  Red Herring A Red Herring is a fallacy in which an irrelevant topic is presented in order to divert attention from the original issue. The basic idea is to "win" an argument by leading attention away from the argument and to another topic. This sort of "reasoning" has the following form: Topic A is under discussion. Topic B is introduced under the guise of being relevant to topic A (when topic B is actually not relevant to topic A). Topic A is abandoned.  Slippery Slope - The Slippery Slope is a fallacy in which a person asserts that some event must inevitably follow from another without any argument for the inevitability of the event in question. In most cases, there are a series of steps or gradations between one event and the one in question and no reason is given as to why the intervening steps or gradations will simply be bypassed. This "argument" has the following form: Event X has occurred (or will or might occur). Therefore event Y will inevitably happen. 7  Straw Man The Straw Man fallacy is committed when a person simply ignores a person's actual position and substitutes a distorted, exaggerated or misrepresented version of that position. 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; he or she has 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. 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 8 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.