The Informal Fallacies

The Informal Fallacies

One way to characterize a fallacy, or a fallacious argument, is to say that it is an argument that purports to establish its conclusion but in fact fails to do so. A fallacious argument under this interpretation is a kind of invalid or unsound argument. Another way to specify a fallacy is to say that it is a mistake, or error, in reasoning. Such reasoning may at first glance seem reasonable, but, as looks are sometimes deceiving, a more careful examination reveals its fallacious nature.

Both characterizations of a fallacy, while correct in their essentials, are inadequate for several reasons. First of all, a fallacy must be regarded not as a particular unsound argument or piece of faulty reasoning but as a general kind of such an argument or reasoning. The idea behind the classification of fallacies is to group together all the arguments or reasonings that make the same mistake and to label or name the categories thus produced. Each bad argument or reasoning is then viewed as an instance of the fallacy.

There is a difficulty, however, if we take a fallacy to be a faulty bit of reasoning, as the second definition above suggests. In order to classify the various patterns of unsound reasoning, we would have to know just how many ways a person could make a mistake in reasoning;a monumental task indeed! Also, since reasoning, understood as a deliberate act or series of acts of contemplation, is to a large extent dependent on the psychological nature of the individual thinker, our characterization of a fallacy in terms of reasoning would make the topic of fallacies more appropriate to a textbook on psychology then to one on logic. Logic is not a branch of psychology, so fallacies, properly speaking, should not be thought of as just bad reasoning.

On the other hand, if we view a fallacy as an invalid argument, then we run into problems of a more technical nature. Since all inductive arguments are (deductively) invalid, they would all have to be considered fallacious if all we meant by "fallacy" was "invalid argument." This, of course, is something that should not be done, for there are perfectly good strong inductive arguments. More important, since the fallacies, once properly recognized and named, would have to be viewed as types of invalid arguments (or, as we shall say later, "invalid argument forms"), it would seem that we have committed ourselves to the view that all arguments having a particular invalid form are invalid arguments (since all fallacies are invalid arguments and all instances of the named fallacies are fallacies). However plausible this may seem, it is not correct. While it is true that all arguments having the same form as a valid argument are valid arguments, the same cannot be said of invalid arguments. That is, not all arguments having the same form as an invalid argument are invalid arguments. This point will be made more clear in subsequent lessons. It is mentioned here only to help set the stage for a more reasonable discussion of the fallacies.

Perhaps the most plausible way to think about the fallacies is to regard them as patterns of argumentation that on the surface seem to be sound but that, in fact, do not represent totally reliable means of establishing a conclusion. By studying the fallacies, you should gain insight into the more common ways in which argumentation can go awry. Knowing how many ways people can be "tricked" into believing something should help you recognize and avoid bad arguments. The fallacies, then, represent pits into which either speakers (or writers) fall when they present bad arguments or members of the audience (or readers) fall when they accept conclusions on the basis of bad arguments.

Although it is possible to define the various fallacies in such a way that any instance of the named fallacy will contain an invalid or weak argument, it is better to think of each fallacy as a specific manner of arguing in which an invalid or weak argument may (but not necessarily will) occur. Each fallacy will then be represented by a typical form of faulty argument that often occurs in such fallacious argumentation. Whenever you recognize that a stretch of argumentation is fallacious, you should be on the lookout for the typical form of invalid or weak argument associated with that fallacy. The invalid or weak argument may or may not be present, but you should always watch for it and maintain a healthy skepticism toward any argument presented to you in a fallacious manner. Furthermore, since fallacious argumentation often results in bad arguments, such argumentation should be recognized for what it is and be avoided in most contexts. Fallacious argumentation is analogous to reckless driving. If one drives recklessly, one may or may not end up in an accident, but one has certainly increased the chances of having an accident.

In order to define the fallacies, we need to define what is meant by an "argumentative situation." Let us say that an argumentative situation is one in which argumentation takes place and that it consists of these three components: a speaker, an opponent, and an audience. The speaker argues for a position that is contrary to the opponent, and the audience is the person or persons the speaker and opponent are trying to persuade. The speaker attempts to convince the audience to accept his or her claim, while the opponent attempts to convince the audience to accept an opposing claim. A debate is a typical argumentative situation in which affirmative (proponent) and negative (opponent) speakers urge the audience (the judge) to, respectively, adopt or reject the relevant proposal. An newspaper editorial represents another type of argumentative situation in which the speaker is the author of the editorial, the opponent is anyone who urges a view different from that of the author, and the readers of the newspaper constitute the audience. Also, a single person may be the speaker, the opponent, and the audience as when an individual deliberates over, for example, the best course of action to take in a given situation.

We divide the fallacies into two groups: the fallacies of relevance and the fallacies of ambiguity. The distinction between these groups is rather rough and imprecise and probably really does not not need to be made in order to understand what the fallacies are. Nevertheless, we can say that a speaker commits a fallacy of relevance when he fails to argue in a straightforward manner for his claim, instead bringing up issues that aren't directly related, or pertinent, to establishing the desired conclusion. A fallacy of ambiguity is committed when a speaker, in the course of argument, uses language that is either unclear or involves a shift, or change, in meaning.

Many of the more traditionally recognized fallacies have Latin names. Not all these Latin names need be remembered; however, some of them have become so standard that you need to know these names in order to understand the vocabulary of informal logic. In our discussion to follow, we shall let you know when it is important to remember the Latin name of the fallacy under discussion.

Argument from (Appeal to) Ignorance, Argumentum ad Ignorantiam

A speaker commits the fallacy of an argument from ignorance when he either argues for his position by claiming that it has never been disproven or urges the audience to reject his opponent's position by claiming that it has never been proven. In the former, the speaker claims that since what he is arguing for has never been disproven, or there is little or no evidence to the contrary, there is good reason to accept his conclusion. In the latter case, the speaker claims that his opponent's conclusion ought to be rejected since it has never been conclusively established, or little or no evidence can be given in its support. In other words, the speaker is attempting to convince the audience either that, since his conclusion has not been proven false, it is true or that, since his opponent's conclusion has not been proven true, it is false.

One who argues, for instance, that we should continue to fund the space program's search for extraterrestrial life since the existence of such life has never been disproven commits this fallacy. The suggestion is that, since the existence of extraterrestrial life has not been disproven, there must be such life forms and that it supposedly follows that we should spend money attempting to find these living things.

Not all cases of an appeal to ignorance result in faulty arguments. It would seem reasonable, for instance, to conclude that, since a lengthy, exhaustive criminal investigation had yielded no evidence of wrongdoing, the suspect is probably innocent. Likewise, if a scientist is searching for evidence of the existence of some proposed theoretical entity and can find none after performing numerous experiments, then he or she is probably justified in rejecting the proposed theory.

The argument from ignorance may be seen as a special case of a more general type of fallacy that we may call the argument from bare possibility. In arguing that a particular claim has not been disproven or that a contrary claim has never been proven, the speaker is saying, in effect, that the claim may be true, and from this concludes that the claim is true. This represents an inference from what may be true, or what is merely possible, to what is actually true.

An example of an argument from bare possibility that is not an argument from ignorance is illustrated by the following conversation between two people, Jeff and Susan.

Jeff: "Susan, loan me ten dollars."

Susan: "Why should I? How do I know you'll pay it back?"

Jeff: "I just bought a lottery ticket!"

Susan: "So what?"

Jeff: "Well, I just may win a million dollars, and if I do, I'll certainly be in a position to pay you back. So you see, you have nothing to worry about."

Jeff is here arguing that since it is possible for him to win the lottery by buying a ticket and his winning would enable him to pay back the debt, he will, in fact, be in a position to pay Susan back the money borrowed. Jeff is, consequently, arguing from what is merely possible to what is actual, which is the argument from bare possibility.

Appeal to Authority, Argumentum ad Verecundiam

The speaker commits this fallacy when he urges his audience to accept his position, or to reject the opponent's position, solely on the basis of the testimony of a recognized authority or of an authoritative source. Typically, one might say, "You can believe that X is the case since Y says it is the case." A faulty argument is the result of such an appeal if either the authority cited is not an expert when it comes to the topic under discussion or the opinion of the authority is not relevant to the issue at hand.

The U.S. senators who argued some years ago that it was best not to extend the visas of Chinese students living in this country because George Bush didn't think that was such a good idea were making a rather blatant appeal to authority. Those who argue that abortion is murder because the Bible says so are appealing to an authoritative source whose testimony is not recognized as being authoritative or particularly germane in secular, legalistic discussions of this issue.

Commercial advertising makes frequent use of appeals to authority. A well-known, respected figure in politics, sports, or entertainment is used to endorse a product, and through such an endorsement you are strongly encouraged to accept the claims of the manufacturer. You are expected to believe that the product is the best on the market, in spite of the fact that, for all we know, the authority figure has only a passing acquaintance with the product.

Not all appeals to authority, of course, result in faulty arguments. Since it is impossible for any one person to be an expert in all subjects, despite those certain individuals who claim the contrary, we all must occasionally rely on the wisdom of others in order to reach a coherent understanding of the world around us. Such reliance is not unreasonable so long as we are mindful of the ultimate source of that knowledge and place our trust in the accuracy of the information to an extent no greater than the reliability of the source of that information.

Complex Question

The fallacy of complex question is committed by the speaker when he poses a bad, or misleading, question to his opponent and then makes an illicit inference from his opponent's answer. The question posed is misleading, because it presupposes that an issue at stake has already been settled. The opponent is usually forced to answer the bad question with a "yes" or a "no," and, either way, the speaker has him cornered. For instance, Tom asks Joe, "Have you stopped beating your wife yet?" If Joe answers "yes," Tom will conclude that Joe is a reformed wife abuser, and if Joe answers "no," Tom will conclude that Joe is continuing to abuse his wife. From either one of these conclusions, Tom then infers that Joe really should be ashamed of himself for having mistreated his wife. The problem, of course, with this question is that, for Joe's yes or no answer to be appropriate, it must already be taken for granted that at some time Joe started to beat his wife, and this is something that Joe may never have done.

Here is a real example of the use, or abuse, that can be made of a complex question. Several years ago the Moral Majority distributed a questionnaire that was allegedly designed to survey public opinion on several current issues such as abortion and pornography. Rather than conduct an objective, unbiased survey, they chose instead to state the questions in such a fashion that everyone responded to each question in the way the Moral Majority desired. One of the questions was phrased in a manner very similar to the following:

Do you favor, yes or no, abortion on demand, which last year resulted in the murder of over 3,000 innocent babies?

The problem with this question is that for a "yes" or "no" answer to be even meaningful it must be taken for granted beforehand that abortion is murder and that human fetuses are innocent babies. If a person answered "yes" to this question under these circumstances, it meant that the person believed in murdering innocent people. This was hardly going to be the response of anyone who took the question seriously, since murder is not a moral act, so the Moral Majority more or less ensured that the answer to this question was "no." Another way to look at this question is to say that the answer is buried in the very statement of the question in that the answer is so strongly suggested by the question as it is stated. The Moral Majority went on to infer from the "no" answers given to this and to the remainder of the questions that the public, by and large, agreed with them on several key issues. This inference was, of course, unjustified.

An argumentative strategy similar to that represented by the complex question is that of the fallacy of the false dilemma (or fallacy of the faulty dilemma). Instead of posing a "yes" or "no" question to the opponent, the speaker simply gives the audience, or the opponent, two options concerning the issue at hand. The speaker will typically say something such as, "You must either believe that X is the case or believe that Y is the case." The speaker will then proceed to rule out one of these options by arguing that it is false or implausible. As a result, he will then infer that the other option is true or is the only reasonable alternative.

Occasionally, a speaker follows a different strategy by ruling out both possibilities, thus creating a problem since there are then no options from which to choose. The speaker then concludes that a certain claim or claims made by the opponent must be false since their truth was needed in order to generate the dilemma.

The problem with either style of argumentation is that it will lead to a true conclusion only if it is taken for granted that the two options represented by the either-or claim are the only available options. This assumption is analogous to the assumption involved in the case of the complex question, where it must be taken for granted that, one way or another, a "yes" or "no" answer to the question is appropriate.

The fallacy of the faulty dilemma is committed by some proponents of creationism when they argue that, since one is either an evolutionist or a creationist, one must be a creationist because the evolutionist's theory is extremely improbable. Their argument is faulty since there are theories or accounts of the origin and development of life other than creationism or evolution, and there are numerous versions of these latter two that are not ruled out or opted for in their argument.

Argument to the Man, Argumentum ad Hominem

When the speaker, instead of addressing the issues at hand, chooses to discuss the personal nature of his opponent, thereby encouraging the audience to reject the opponent's claims, the speaker is said to have presented an ad hominem argument. The Latin phrase "ad hominem" is important to remember. The fallacy committed is clearly one of relevance since a person's age, sex, natural origin, party affiliation, occupation, voting record, and other personal attributes do not in general have anything to do with the truth or falsity of what a person says or believes. People who are quite often mistaken in their beliefs or who hold unpopular views sometimes say things that are both true and admirable, so it is an unreliable inference to conclude, solely on the basis of the individual's personal profile, that what the person claims must be false. Generally, the form of faulty argument associated with this fallacy is, "You can reject the claim X because Y says it is true." (Contrast this with the general form of argument associated with the appeal to authority.)

We can distinguish between two types of ad hominem fallacy: the abusive ad hominem and the circumstantial ad hominem. There are, in turn, two distinct ways in which either one of these fallacies can be committed, so there are, in effect, four different kinds of ad hominem argumentation.

Abusive ad Hominem

A speaker using the abusive ad hominem always engages in character assassination of his opponent. This attack can be launched directly, or it can be effected through more subtle techniques. In a direct assault on the opponent's character, the speaker reveals that his opponent has some objectionable character trait that supposedly makes the truth of his claims less likely. Conservative politicians may, for example, point out that their opponents are left-wing radicals, thereby urging fellow conservatives to dismiss their rivals' proposals. When a speaker boldly declares, "My opponent is a jerk; therefore, you can't believe anything he says," we are presented with a rather blatant example of an ad hominem argument.

Often, however, the approach is less direct and more subtle. Instead of explicitly asserting that the opponent has a character defect, the speaker may strongly suggest to the audience that his opponent has such a defect because of the disreputable nature of the people with whom he shares certain beliefs. The speaker is, in effect, suggesting that his opponent is guilty of same character flaw because of his association with people who have a similar character flaw. A strategy employed by some atheists to discredit their opponents' belief in God involved pointing out to the audience that believing in God was widely held among ignorant, barbarous people of ancient times. The suggestion was that anyone who believed in God was likewise ignorant and barbarous. Some creationists, for yet another example, have suggested that evolutionary theory be discarded since Charles Darwin exchanged correspondence with Karl Marx.

Often in the course of an abusive ad hominem argument, the speaker also commits what is called the genetic fallacy when he attempts to discredit a belief by disclosing its origin or genesis. This is a fallacy, because the origin of a belief usually has no bearing on its truth or falsity. The speaker commits both these fallacies when he urges his audience to reject the beliefs of his opponent by showing that such beliefs originate in a source (either the opponent himself or another person or persons who share the same belief) that is unreliable or objectionable. The genetic fallacy is not the same as the abusive ad hominem, for a speaker can commit one without committing the other; however, the latter fallacy is closely associated with the former.

Circumstantial ad Hominem

The circumstantial ad hominem fallacy occurs when the speaker attempts to convince his opponent to reject his own position or accept the speaker's position to conform with his other beliefs or special circumstances. This form of the fallacy is typically, although not always, committed in argumentative situations where the opponent and the audience are the same. The speaker argues that his opponent is extremely inconsistent if he fails to reject a view he espoused or fails to accept the speaker's views. In other words, the speaker charges his opponent with hypocrisy in not rejecting or accepting a particular position. To claim that all Roman Catholics should be against abortion in order for them to conform to official Vatican doctrine is one example of the circumstantial ad hominem. This fallacy is also committed by the officials of industries accused of air pollution when they argue that the claims of the environmentalists should not be taken seriously by the environmentalists themselves and the public at large since all environmentalists drive automobiles that also pollute the air.

In another circumstantial ad hominem argument, the speaker fallaciously argues that his opponent's special circumstances prevent him from presenting on objective, reasoned account of why his position is correct so that there is then little reason to believe what he is saying. In effect, the speaker accuses his opponent of being so biased in favor of a particular position that it is difficult for him to see both sides of the issue. He therefore cannot offer any objective evidence and puts forth mere rationalizations. Those who contend that whatever is advocated by a special interest group should not be given serious consideration since such a group is always motivated by self-interest fall victims to this fallacy. Some feminists also commit this fallacy when they argue that the reason their critics fail to appreciate the need for new legislation prohibiting sexism is because they are men.

An important clarification should be made here concerning the relation between the appeal to authority and the ad hominem fallacy. In discussing the appeal to authority, we said that such an appeal constituted a faulty argument when the authority cited was inappropriate or unqualified. We also noted that the appeal was not unreasonable to the extent that the authority was a reliable source of information. It would seem then that, in rejecting certain appeals to authority as fallacious, we are relying on an ad hominem fallacy, since we reject a particular argument not on the basis of its premisses or conclusion but on the qualifications of the person giving the evidence. From a purely logical point of view, a person's qualifications, as is the case with other personal attributes, have no bearing on the truth or falsity of what he or she says. Why, you may ask, is it permissible to label as fallacious an ad hominem argument while at the same time to rule out certain appeals to authority on the basis of the nature of the authority cited? The reason we regard certain appeals to authority as fallacious is not due solely to the nature of the authority cited. When an appeal to authority is legitimate, it is reasonable to assume that the person or persons cited can verify the claims made. If we cited the testimony of a credible scientist, for instance, we could take for granted that such a person would have pefformed the necessary experiments or gathered the appropriate data to substantiate the reported findings. The trouble with an appeal to an inappropriate authority is that it is not reasonable to just assume that the person or persons cited have reliable first-hand knowledge to back up their claims, for what they say appears to be nothing but hearsay. Thus, the appropriateness of the authority cited is relevant to the reasonableness of the appeal.

On the other hand, when the speaker gives an ad hominem argument, thereby urging the audience to reject the opposing view merely on the basis of the opponent's personal character, the nature of the opponent's character is usually completely irrelevant to any reasonable determination of the truth or falsity of the opponent's claims. There is, in the typical case, no underlying assumption that will make the ad hominem argument plausible in virtue of its premisses supplying information needed to assess the reliability of the competing claims. This is why we can regard a particular ad hominem argument as fallacious at the same time that we regard certain appeals to authority as legitimate.

One other point should be made here before we discuss the other fallacies. You will recall that, in the introduction to this lesson, we noted that weak or invalid arguments may not always result from the kind of argumentation that is labeled "fallacious." Although such bad arguments typically are the products of such argumentation, occasionally a strong or valid argument is produced. Sometimes an ad hominem argument (an argument that is presented in the course of ad hominem argumentation) is not unreasonable. If, for example, John argues that he should not loan Bill money because Bill is dishonest, then John is technically giving an ad hominem argument; nevertheless, it is a fairly good argument. In this case Bill's dishonesty is relevant in determining whether he is likely to repay a loan, and if he is unlikely to do so, then John judges that he should not loan him the money.

Fallacy of Accident

When the speaker uses a generalization in a stretch of argumentation that allows him to draw a conclusion about a particular case not covered by that generalization, has has committed the fallacy of accident. Almost all generalizations are of such a nature that they admit exceptions and hold true only over a certain range of cases. The person who commits the fallacy of accident does so by inappropriately applying the generalization to a case where the generalization does not hold true. The speaker succumbs to this fallacy by ignoring, either intentionally or unintentionally, the special or accidental circumstances of a particular case that renders the generalization inapplicable.

The person who argues that, since society always permits people such as police and firemen to travel faster than the posted speed limit, he should have the right to do likewise is offering an argument that is so blatantly a fallacy of accident that hardly anyone would be convinced by it. A more serious argument has been given by the opponents of capital punishment: if the deliberate killing of a human being is always murder, then it follows that the execution of a criminal is also murder; therefore, the state is no less guilty of a crime than is a convicted killer. The proponents of capital punishment see this argument as a fallacy of accident. They claim that murder involves the killing of an innocent person. A convicted murderer is not an innocent person so applying the generalization about what constitutes murder to the execution of a criminal is inappropriate. Therefore, the state's execution of a convicted killer should not be interpreted as a crime.

Fallacy of Converse Accident

A better name for this fallacy is "hasty generalization." Since students tend to confuse the fallacy of accident with the fallacy of converse accident, we shall use the less confusing name, "hasty generalization," which is what you should remember to call this fallacy. A hasty generalization is the result of the speaker inferring the truth of a generalization on the basis of a small number of cases that are compatible with the truth of the generalization. What usually happens is that, in a few cases, we observe a relationship between two different kinds of things, and we then infer a general relationship. For example, we note that Hiroshi is Japanese and a good mathematician and that Roichi is Japanese and a good mathematician. If we then conclude that all Japanese are good mathematicians, we would be making a hasty generalization. This is a fallacious argument, for there is no guarantee that the generalization is true just because a few of its instances happen to be true.

Please note the difference between the fallacy of accident and the hasty generalization. Both of these involve a generalization, but the fallacy of accident represents a pattern of inference essentially the reverse of that represented by the hasty generalization. The former is a movement from what is true generally to what is true in a particular case to what is true generally. These two inferences are distinct, even though there are more complicated arguments that involve both of these fallacies.

Fallacy of False Cause

The fallacy of the false cause is committed when the speaker concludes, or suggests to his audience, that because one event follows another, the first event is the cause of the second. This inference is fallacious, because causal connections between events are difficult to establish and require of separate events more than mere temporal succession.

Manufacturers of diet pills give a false cause when they claim their product to be causally effective solely on the basis that some overweight people have taken the pills and have subsequently lost weight. A politician, in order to get re-elected, sometimes relies that his constituents will accept a false cause by urging voters to support him because, after he was elected the first time, the crime rate dropped by twenty percent.

Begging the Question, Petitio Principii

The speaker is said to beg the question when he argues in such a fashion that he assumes (takes for granted) the truth of the very proposition he is trying to prove. Typically, such an argument either will contain a conclusion that is a restatement of one of the premisses in the same or a different form or will have a premiss that can be believed to be true only if the truth of the conclusion has already been granted. An argument whose conclusion is one of its premisses is clearly unconvincing, but such an argument can be quite deceptive when the conclusion restates the premiss in an entirely different form. The most deceptive question-begging arguments are those with at least one premiss whose truth presupposes the truth of the conclusion.

As an example of the first kind of argument, consider the following one- sentence argument: Joe is smarter than Tom because Tom is less intelligent than Joe. In this case, the conclusion, "Joe is smarter than Tom," expresses the same proposition as that expressed by the premiss, "Tom is less intelligent than Joe," so that the premiss and the conclusion are restatements of one another. An example of the second kind of question-begging argument is provided by the following argument:

The Bible is the word of God. The word of God is completely true. The Bible says that God exists. Therefore, God exists.

Clearly, an atheist is not going to be persuaded by this argument, for if one doubts the truth of the conclusion, then one will not be willing to accept the truth of all the premisses. In fact, one will believe the first two premisses only if one already believes the conclusion.

In addition, another strategy may be employed by argumentation that begs the question. Consider this modified version of the preceding argument:

The Bible says that it is the word of God. The word of God is completely true. Therefore, the Bible is the word of God.

Assume, for the sake of the discussion, that this argument occurs within a context in which it is not taken for granted that the Bible is completely true. In this situation, is this a good argument? No! In order for the two premisses to imply the conclusion, it still must be taken for granted that the Bible is the word of God, which is, of course, the conclusion. If the Bible is the word of God, then by the second premiss we know that the Bible is completely true. If the Bible is completely true, then what it says is true; hence, from the first premiss we can infer that the Bible is the word of God. By assuming that the Bible is the word of God, we have reached the conclusion of this argument; therefore, one is required already to have accepted the conclusion of the argument in order to be led by the premisses to accept the conclusion.

Regardless of the form it takes, all argumentation that begs the question is called circular reasoning: one can know that the conclusion of a question- begging argument is true if one knows that its premisses are true, and one can know that its premisses are true if one knows that the conclusion is true. Any argument that begs the question is valid. It may not, however, be sound, for it is impossible for all the premisses to be true at the same time that the conclusion is false. No argument that begs the question should convince anyone of the truth of its conclusion, for no such argument provides any independent grounds for accepting its conclusion.

Rather than present reasons and evidence in support of some contention, the speaker may try to gain the sympathy of his audience in order to promote the acceptance of his claims. Under such circumstances, the speaker is said to have made an appeal to pity. The appeal to pity is accomplished by getting the audience to feel sorry for the speaker so that they will then be more willing to go along with what he says. Although this technique can sometimes be extremely effective, the particular plight of the speaker and the emotional reaction to it by the speaker and his audience usually have no bearing on the truth or falsity of what he desires his audience to believe.

Sometimes, after an examination has been given, students may make an appeal to pity in an attempt to influence their grade. On handing in the examination, a student may look directly into the eyes of the instructor and say, "I must do well on this exam; otherwise, I will probably have to drop the class and may have to change my major."

Appeal to the Masses, ad Populum

One type of ad populum occurs when the speaker attempts to arouse the common sentiments, fears, hopes, and desires of the audience in such a way that they are emotionally compelled to accept the speaker's conclusions. The appeal to emotions is successful when the speaker causes his audience to form a psychological association between what he advocates and the emotionally charged beliefs, prejudices, and attitudes of his audience. Politicians appeal to emotions when they tell voters that the beliefs of their political party are in accordance with traditional American values and will lead to the realization of the American dream. Advertisers' greatest tool seems to be the ad populum. A television commercial that offers us no reasons for buying a particular make of automobile but instead urges us to buy a new Chevrolet because "It is the spirit of America" classically illustrates this fallacy.

The other type of ad populum argument occurs when the speaker attempts to persuade his audience to accept his claims by arguing that, when it comes to the issue at hand, most people agree with his beliefs. This kind of argument would be reasonable only if it were reasonable to assume that the masses (the majority) are always right (i.e., that whatever is believed by the majority of people is always correct). This assumption, of course, cannot always be made. The automobile dealer who encourages potential customers to buy a particular

car because it is the number one import in America uses this kind of ad populum. Presumably, the fact that it is the number one import car in the U.S., if true, means that most people believe it to be the best imported car. The conclusion that one should buy the car is then only going to follow if it is taken for granted that most people cannot be wrong about this car. Both types of ad populum are in general fallacious since it does not follow that, because a belief is popular or makes one feel good, it must be true.

Appeal to Force, ad Baculum

When the speaker abandons reason altogether, trying to convince the audience that what he believes must be regarded as true through threats, the speaker makes an appeal to force. Such threats may either be rather blatant ("You had better believe X, or you will suffer the consequences") or be veiled behind talk of factual matters that is merely suggestive of a threat. During the Inquisition, people were told to align their beliefs with the official church doctrine because the penalties for heresy were severe. Nowadays those who serve in public office may be encouraged by some of their constituents to support a particular issue, being reminded that they need those votes to get re elected.

Irrelevant Conclusion

When in the course of a discussion the speaker presents an argument that, even if it succeeds in establishing its conclusion, is directed at substantiating a claim that is irrelevant to the issue at hand, the speaker is said to have committed the fallacy of irrelevant conclusion. Perhaps a better name for this fallacy would be "irrelevant argument," for it is not just the conclusion but also the premisses and the entire line of argumentation that is often irrelevant. Sometimes this fallacy is committed in the context of argumentation that involves premisses which support a conclusion that is somewhat relevant but which is, however, different from the one the speaker is trying to establish. For example, Ronald Reagan often cited the need for a strong national defense as a reason for continuing to fund Star Wars research. The trouble with this argument is that the need for a strong national defense could only warrant the need for some form of defense system and could not, by itself, justify the enormous expenditures associated with the particular defense system Reagan had in mind.

Occasionally, in the course of a long stretch of argumentation, the speaker will, intentionally or unintentionally, stray from the issues under discussion and argue for positions that are irrelevant to his overall conclusion. This represents probably the most typical situation in which the fallacy of irrelevant conclusion is committed. When the speaker deliberately departs from what is pertinent to the discussion in order to divert attention away from the weak parts of his argumentation, he is also said to have "avoided the question" (or "evaded the issue") An argument with an irrelevant conclusion and with premisses that have no logical connection with the conclusion is said to be a non-sequitur. A non- sequitur argument is always irrelevant since no such argument provides justification for accepting its conclusion.

Thus far we have considered fallacies of relevance. We now turn to fallacies of ambiguity.


The speaker commits the fallacy of equivocation when he uses a word or expression in more than one sense. The same word or expression will occur at least twice in the argument, but different meanings will attach to these different occurrences. When this happens, the speaker is said to be equivocating on the term or expression. The equivocation will result in a weak or unsound argument when the equivocal use of terms blocks the inference from premisses to conclusion.

As an example of this fallacy, consider the following argument:

Only man is rational.

No man is a woman.

Hence, no woman is rational.

This argument is unsound! The reason that it fails to establish its conclusion is that the word "man" is being used in two different senses. In the first premiss, "man" stands for "the human race"; in the second premiss, "man" stands for "male human being." This equivocation on the word "man" makes impossible the needed logical relation between the two premisses and thus prevents the premisses from implying the conclusion.

Be careful when using relative terms (such as large, small, fast, slow, heavy, light, etc.), for such terms have a more definite meaning only in the context in which they occur. With these terms, a person can easily equivocate, and Copi mentions this as another way an argument can illustrate the fallacy of equivocation. Consider the following argument:

Timbo is a small elephant.

All elephants are animals.

Hence, Timbo is a small animal.

Here the equivocation is on the word "small," but this word is not being equivocated on in isolation. The expressions small elephant" and "small animal" refer to two entirely different kinds of small things even though the word "small" occurs in each expression. Since nothing that is a small elephant is anything that could be considered a small animal, and vice versa, the required logical connection between premisses and conclusion does not exist, rendering the argument unsound.


An amphibolous statement is one expressed in so awkward a manner that more than one interpretation of its meaning is possible. The context in which the amphibolous statement occurs may nevertheless determine which of the possible meanings is the intended one. The speaker commits the fallacy of amphiboly when he argues in such a way that an inference he makes using an amphibolous premiss is possible only if that premiss is interpreted in a manner inconsistent with the intended meaning of the statement of that premiss.

For example, the person who drives down the highway, sees a sign in front of a small eating establishment, and makes the following argument commits the fallacy of amphiboly.

The sign reads "Eat and Get Gas." Therefore, they must serve a lot of beans and spicy foods at the place.

Please note the distinction between the fallacy of equivocation and the fallacy of amphiboly. The former involves two or more occurrences of the same word or expression with separate and distinct meaning attached to each occurrence. The latter involves only one occurrence of an entire sentence whose meaning is indistinct because it is interpretable in more than one way.

Fallacies of Relevance

Argument from Ignorance (Appeal to Ignorance)

Argument from Bare Possibility

Appeal to (Inappropriate) Authority

Complex Question

False Dilemma (Faulty Dilemma)

Abusive ad Hominem

Circumstantial ad Hominem

Genetic Fallacy

Fallacy of Accident

Fallacy of Converse Accident (Hasty Generalization)

False Cause (Post hoc ergo propter hoc)

Begging the Question (Circular Reasoning)

Appeal to Pity Appeal to the Masses (Appeal to Emotions)

Appeal to Force

Irrelevant Conclusion

Ignoring the Question (Evading the Issue)

Non-Sequitur Argument


Fallacies of Ambiguity