CRITICAL THINKING FAULTY REASONING (VAUGHN CH. 5) LECTURE PROFESSOR JULIE YOO Formal v Informal Fallacies Irrelevant Premises Genetic Fallacy Composition Division Appeal to the Person (ad hominem/tu quoque) Equivocation Appeal to Popularity Appeal to Tradition Appeal to Ignorance Appeal to Emotion Red Herring Straw Man Unacceptable Premises Begging the Question False Dilemma Slippery Slope Hasty Generalization Faulty Analogy Faulty Reasoning (Vaughn Ch. 5) Page 1 of 8
FORMAL V INFORMAL FALLACIES Some reasoning can be formalized. This means that we can formulate the reasoning almost like an algebraic formula with variables that can take on any sentence as individual values. We already saw some examples of formal reasoning, namely, modus ponens, modus tollens, hypothetical syllogism, and disjunctive syllogism, along with many different types of categorical syllogisms. These are good ways of no matter what you substitute in for the content of the antecedent or consequent, which is the hallmark of valid deduction. Other ways of reasoning, however, are highly sensitive to the content; they cannot be formalized. Inductive reasoning, in fact, is informal in this sense. For instance, how many dogs must you need to sample in order for All dogs bark to be a strong inductive generalization? There is no way to specify in advance how many samples one needs. Faulty reasoning can be divided into two broad kinds, according to whether the reasoning is formal or informal. Formal fallacies include denying the antecedent and affirming the consequent. The ones we will examine here are of the informal variety, which means that the badness of the reasoning is highly sensitive to the content and the context in which they are generated. Even though the reasoning is bad, these fallacies often have a compelling pull upon the listener, which is probably why they are committed so often and thus have acquired names. IRRELEVANT PREMISES Genetic Fallacy Definition: An argument commits the genetic fallacy when something is claimed to be true (or false) solely because of its origin. The world was created in 6 days because the Bible says so. Gay marriage is illegal because the Pope disapproves of it. You can forget about the rumors of John Edwards s affair because it was reported in the National Enquirer. This type of reasoning is fallacious because it does not defend (or criticize) a claim on the basis of its merit, but rather on its source. In general, where an idea comes from is irrelevant to its truth (or falsity). It can be good or bad, regardless of who or where it comes from. Caveat: This might be a bit confusing, since this seems to conflict with using experts as a legitimate source of evidence. As we say in the previous chapter, in some cases, it is perfectly legitimate to believe something because an expert claims that it is true. In fact, many of our beliefs are justified in this way. The difference between legitimately using and expert and committing the genetic fallacy comes down to the way in which the source is cited: when one commits the genetic fallacy, one simply assumes that there is no more to backing up a conclusion than citing the source, whereas in a legitimate use of experts, one cautiously cites the track record of a source (the expert) as one among several factors in supporting the conclusion. Faulty Reasoning (Vaughn Ch. 5) Page 2 of 8
Composition Definition: An argument commits the fallacy of composition when one assumes that just because the parts of a thing have a certain feature, the thing itself has that feature. The molecules in the ocean are smaller than a pin, and so the ocean is smaller than a pin. Every organ, such as the eyes, heart, lungs, in a person serves a purpose, so the person himself or herself must also serve a purpose. Individuals contribute $100 a year to the orphanage, whereas corporations contribute $1,000 a year. So the orphanage gets much more of its money from corporations than from individuals. The first example is fairly easy to detect as a fallacy, but the second example, though equally a fallacy, might sound plausible. However, the argument is certainly no acceptable, not only because it commits the fallacy of composition, but because it equivocates on the term, purpose. In its first occurrence, it is used in the sense of biological purpose, but the second occurrence is not clear about what type of purpose is being suggested moral, social, spiritual? Caveat: Not all instances of thus type of reasoning are result in a false or dubious conclusion. Consider a fancy five-course meal. Suppose every part of the meal each one of its courses was delicious. It is reasonable to conclude that the whole meal was also delicious. In this case, compositional reasoning led to an acceptable conclusion. This means that it really depends on the subject matter and the context in which this reasoning is used. Division Definition: An argument commits the fallacy of division when one assumes that just because a thing has a certain feature, its parts also have that feature. The cake Jack baked is very sweet, so each ingredient in Jack s cake must also be sweet. The boat floats upon the water, so each part of the boat must also float upon the water. The orphanage gets a greater portion of its charity from corporations than from individuals. So corporation X must have contributed more than individual Y. Caveat: The fallacy of division is reverse of the fallacy of composition. It involves the illegitimate inference from the nature of the whole to its parts, or a characteristic of a group to its members. Just like its cousin, there are instances of divisional reasoning that are not fallacious. Faulty Reasoning (Vaughn Ch. 5) Page 3 of 8
Appeal to the Person (ad hominem/tu quoque) Definition: An argument commits the ad hominem fallacy when discredits a claim by attacking its author. Animals and humans didn t evolve. The people who say they did are godless atheists who want to lie to our children. Congressman X says that we have to increase state taxes to fund public education. But his is preposterous. Of course Congressman X would say that; he has 6 children who are all in public schools. You can t give the job of US Surgeon General to Dr. Regina Benjamin because she s really fat. How good can she be at her job of prescribing health standards for all Americans if herself is overweight? Claims have to be judged on their own merits, not on the basis of the character, motives, or circumstances of their authors, which are usually irrelevant to the merit of the claim. In an ad hominem, these are brought to bear on the credibility of a claim, and there are many versions of it. There is what is known as an abusive ad hominem, where one discredits the claim by attacking author of the argument; this is illustrated in the first example. Another is what is known as circumstantial ad hominem, where one discredits the claim by attacking the circumstances of the author; this is illustrated in the second example. And another kind is known as tu quoque, which is when one uses the charge of hypocrisy to discredit the hypocrite s claim; this is illustrated in the second example. Caveat: Sometimes, the context or situation demands that we take the credibility of a person into account when evaluating the truth of what they say. If a witness in a trial has been proven to be a frequent liar, then we have to suspend our belief about their claim (not disbelieve their claim outright). Another situation might be a job that calls for a high degree of personal ethics, like the priesthood or some branches of public office. Equivocation Definition: An argument commits the fallacy of equivocation when one uses a word in two (or more) different senses when drawing the conclusion. Smith is the murderer because the one who killed Jones was at the bank at noon, and Smith was at the bank at noon. Only God can perform miracles, which can be seen in the smile of a child. So simply by seeing happy children we can know that God exists. An equivocated word need to reappear in the argument in order for the fallacy of equivocation to take place. This reappearance is present in the first example, but not in the second. In the second example, the argument uses the word miracle only once, but in a deliberately ambiguous way, one to mean the violation of laws of nature (like parting the red sea, a talking Faulty Reasoning (Vaughn Ch. 5) Page 4 of 8
burning bush, etc.), which is the literal sense of miracle that would strongly support God existence, and the other to mean a thing of beauty, which is a figurative sense of miracle that has no support for God s existence. Appeal to Popularity Definition: An argument commits the fallacy of appeal to popularity when it argues that a claim must be true because a lot of people endorse it, or false because a lot of people reject it. So many people believe that there is a Higher Power. So surely there has to exist some divine being, which we call God. If we want better public schools, we need to raise taxes. But that is a bad policy because everyone will hate paying higher taxes. Of course a majority of the people can believe a claim and the claim turns out to be true, but surely the claim is not true because a majority of the people believe it. Yet the fallacy of the appeal to popularity makes exactly this assumption. The same goes for the falsity of a claim and a majority of the people rejecting it. Another fallacy known as appeal to tradition works in a similar way. An argument commits the fallacy of appeal to tradition when it argues that a claim must be true because it s a part of tradition, or false because there is no tradition. Appeal to Ignorance Definition: An argument commits the fallacy of appeal to ignorance when it argues for a claim from the very lack of evidence. There is no evidence that unicorns don t exist. So there must be unicorns. It s just that they have never been seen. There is no concrete evidence that life evolved from inanimate matter. So that must mean that God created living things. From a lack of evidence, you cannot conclude one thing or another. And yet, the fallacy is drawing exactly this kind of conclusion. Caveat: This is different from when we conduct a careful experiment or test and in its search for something, finds no evidence of that thing. In this case, there is good reason to reject the existence of the thing that was actively searched for. For instance, there is no evidence that shaking hands with people infected with HIV will pass on the virus. The lack of evidence after a rigorous search is a meaningful piece of evidence. It is thus different from a lack of evidence without a rigorous search. Faulty Reasoning (Vaughn Ch. 5) Page 5 of 8
Appeal to Emotion Definition: An argument commits the fallacy of appeal to emotion when it argues for the conclusion by trying to arouse the listener s guilt, anger, pity, or other emotion. You can t convict this woman. She has suffered her entire life, she has 5 poor children who depend on her, and because of her cancer, she only has two years to live. A claim is believable or not depending upon the evidence there is backing it up; the emotions that happen to be aroused in the listener (or in the author) are usually not relevant to the evidence for the claim. Often, the fallacy will use visual or cinematic aids. Caveat: Not all appeals to emotion are fallacious. Sometimes, a moving description of a tragic situation is an appropriate premise for an argument. For instance, a clear representation of the negative impact of global trading on the children on South America can certainly serve as a relevant premise in an argument why corporations should change their trade policies. Red Herring Definition: An argument commits the red herring fallacy when it raises an irrelevant issue during an argument to throw the opponent off the topic under discussion. Yes, we do spray our produce with carcinogenic pesticides, but that shouldn t stop people from buying our produce. A healthy diet needs lots of fruits and vegetables. Studies constantly show how a healthy diet is essential to a healthy body. We should all try to include more fruits and vegetables in our diets. So people should buy our produce. Did I have an adulterous affair? I worked day and night to raise money for the children s hospital, the hospital that the poor children of our community have been waiting for. I have put in more hours than any of my predecessors in raising money for this much needed hospital. In a red herring fallacy, the arguer usually changes the subject and diverts attention away from the subject matter that is being debated. By doing this, the arguer avoids having to answer hard questions. This is an oft-used trick of many politicians. Straw Man Definition: An argument commits the straw fallacy when it distorts, oversimplifies, or weakens the opponent s argument in order to make it easier to dismiss the opponent s position. Faulty Reasoning (Vaughn Ch. 5) Page 6 of 8
Evolutionists think that you can build an eye from simple cells and chemicals. But surely nothing as complex and sophisticated as an eye can come from such base components! My opponent believes in legalizing medical marijuana, but that is a dangerous and irresponsible view. If people got access to marijuana, you send the message that people can do whatever they want. No society can survive that way. In a straw man fallacy, you basically weaken and oversimplify your opponents argument so that his or her position sounds ridiculous, making it that much easier for you to dismiss it. But this does not really engage with the issues. In addition, you lose the opportunity to strengthen your own view. UNACCEPTABLE PREMISES Begging the Question Definition: An argument commits the fallacy of begging the question when presupposes to truth of its conclusions, rather than independently establishing proving the conclusion. This magic 8 ball answers everything. You want to know who you re going to date in 2 months? Just ask the magic 8 ball. You want to know whether it is reliable? Just ask the magic ball. This is a fallacy because rather than prove that something is the case, the argument already assumes what you are being asked to prove. False Dilemma Definition: An argument commits the fallacy of begging the false dilemma fallacy when it forces a conclusion on the basis of two choices, when in fact there are more choices, and hence conclusions, to consider. You are either a good religious church-goer or a Godless heathen. This is a fallacy because it limits the possible conclusions one can draw from the get-go. By making your opponent believe that there are only the options you mention, you dismiss the alternatives that could be better. Slippery Slope Definition: An argument commits the slippery slope fallacy when it claims that taking a certain step will inevitably lead to a dire conclusion. Faulty Reasoning (Vaughn Ch. 5) Page 7 of 8
If you smoke, you ll become a prostitute. Once you start smoking, you get addicted to other substances. These other substances will be very expensive, and because your body will need it, you ll do anything to satisfy that craving. So you ll turn some tricks just to get money for your drug addiction. Caveat: Not all instances of apparently slippery slope reasoning are fallacious. Sometimes, certain causes will have certain effects that ultimately accumulate to a final situation. Hasty Generalization Definition: An argument commits the hasty generalization fallacy when it draws a grand conclusion from the basis of a very small and unrepresentative sample. I visited New York for a few hours and people were so rude. All New Yorkers are really rude. It is easy for form generalizations (stereotypes) on the basis of a meager sample. How much is enough for a good strong generalization? This is not answerable in advance and independently of the context. Faulty Analogy Definition: An argument commits the faulty analogy fallacy when it draw a conclusion on the basis of an inappropriate analogy or comparison. Every well designed artifact, like a watch, has a designer. The world is well designed. So the world has a designed. These fallacies can be very alluring when the things beings compared seem similar in certain respects. But each case if different, which is why each case needs to be evaluated on its own terms. Faulty Reasoning (Vaughn Ch. 5) Page 8 of 8