Many types of bad reasoning do not begin with an emotional response to an issue. The types listed in Chapter 6 often follow the structure of a good argument, but with some element of that argument distorted. In general, the speaker makes a genuine argument, but one that lacks a proper connection with the truth-claim at stake.

As in Chapter 5, the categories of rhetorical ploy presented here cover the most common kinds of fallacy--so common, in fact, that the major terms of Chapter 6 have entered everyday English.

1. The fallacies covered in this chapter often resemble good reasoning more than the examples from Chapter 5 did. In many cases they start with the structure of a good argument and garble or pervert it.
2. The most common kind of bad reasoning is the ad hominem fallacy. Whatever specific form it takes, the ad hominem mixes up what a claim is saying with the circumstances under which it is said.
3. The fallacy of attacking a straw man consists in arguing against a distorted or simplified version of what someone has said, and treating the argument you give as if it brought down what the person really did say.
4. A false dilemma assumes that only two alternatives exist in a given situation, so that anyone who does not agree with the first alternative has to accept the second one.
5. One invokes a slippery slope when predicting that if one thing happens, or is permitted to happen, another thing (always a very undesirable thing) will eventually result.
6. One of the trickiest fallacies to detect is the one that misplaces the burden of proof. This fallacy occurs when one places the burden of proof on the wrong side of an issue, or places the burden of proof more heavily on one side than it should be.
7. The would-be defense of a claim that relies on the very claim it purports to prove is begging the question. This also gets called "circular reasoning," "starting too close to the conclusion," or (in certain cases, not always) "tautology."

1. The fallacies covered in this chapter often resemble good reasoning more than the examples from Chapter 5 did. In many cases they start with the structure of a good argument and garble or pervert it.

2. The most common kind of bad reasoning is the ad hominem fallacy. Whatever specific form it takes, the ad hominem mixes up what a claim is saying with the circumstances under which it is said.

1. The simplest form of this fallacy, the personal attack ad hominem, maligns a person in order to dismiss that person's beliefs.
1. The personal attacks may be true or false. That doesn't matter.
2. What matters is that with a few special kinds of exceptions, the existence of someone's personal failings does not prove that the person is making false claims.
2. A more specialized personal attack goes by the name of the inconsistency ad hominem. Here one dismisses a claim on the grounds of the speaker's inconsistency.
1. Inconsistency does bring a position down, if a person is asserting both some claim and the contradiction of that claim. When I argue both that vigorous daily exercise is good for my health and that it wears down my organs, you can dismiss my claims on the grounds of their inconsistency.
2. But in one variety of the inconsistency ad hominem, the contradiction between two beliefs reaches back to something that a person said in the past. "How can you say caffeine makes people sleepless, when back in high school you told me it had no effect at all?"
3. A more common variety (called the tu quoque) finds an inconsistency between people's statements and their behavior. "You say this sausage is loaded with cholesterol but I notice you eat it every morning." The person may be a hypocrite, but sausage contains cholesterol regardless.
3. The circumstantial ad hominem, often very close to a personal attack, reduces what someone says to the beliefs of some group that person belongs to.
1. This way of arguing can get abusive; for example, "Of course he thinks the economy is fine. He's a Republican and they don't care about poor people."
2. Still, abuse is not essential to a circumstantial ad hominem. "My doctor says that homeopathic cures don't work, but that's what they have drilled into them in medical school." You may like your doctor just fine, but though the statement contains no tincture of abuse, it becomes an ad hominem by refusing to consider the truth of the doctor's statement.
3. In another twist on the ad hominem, one is poisoning the well by impugning a person's character before that person has even said anything. Poisoning the well gives anything else that person says an implausible sound; thus you may think of it as ad hominem in advance.
4. The genetic fallacy, a very broad category of the ad hominem, rejects a claim on the grounds of its source.
1. That source may be a group or nation. "Calling Dobermans savage dogs is a generalization begun by the Nazis," for instance.
2. In another application of the genetic fallacy one rejects a claim because of the circumstances under which it originates.
1. Here it is not the claim's association with some group that kills it but something allegedly dismissable about the conditions of its birth.
2. A common silly genetic fallacy is the practice of dismissing Jewish kosher laws against pork on the grounds that those laws putatively began as prevention against trichinosis.
5. A final warning: Although these descriptions of the ad hominem have concentrated on its uses to discredit or reject a claim, one may reason identically when accepting a claim on the basis of what splendid or smart people propose it. The ad hominem can be positive as well as negative, and it's just as fallacious either way.

3. The fallacy of attacking a straw man consists in arguing against a distorted or simplified version of what someone has said, and treating the argument you give as if it brought down what the person really did say.

1. A straw man fallacy typically involves a smokescreen (see Chapter 5), because recasting another person's opinion in distorted form amounts to changing the subject.
2. At the same time, such thinking can occur without any intent to mislead. You might misunderstand someone else's view and criticize it on inappropriate grounds. The criticism has still gone wrong, but we would not call that straw man reasoning.

4. A false dilemma assumes that only two alternatives exist in a given situation, so that anyone who does not agree with the first alternative has to accept the second one.

1. The false dilemma distorts a sound logical principle, namely the principle that when there are only two alternatives and the first one does not hold, the second one must. If my cat is not male then my cat must be a female.
2. Thus a false dilemma goes wrong not in its logic but in the move before the logical move, when it falsely describes a situation as though only two alternatives existed, when in fact others exist too.
1. Bear in mind that someone might present the false dilemma in a grammatical form other than "either-or." Any sentence with an "or" can easily be translated into a sentence with "if-then": "A or B" becomes "If not A, then B."
2. Thus a false dilemma like "Either we balance the budget or we all starve to death" becomes, logically, "If we do not balance the budget we will all starve." The sentence structure changes, but not the false dilemma. It's the same fallacy.
3. The perfectionist fallacy uses a false dilemma in a special way; it first assumes that the only two options for action are the perfect success for that action and nothing good at all, then it rejects any proposed action that will not work perfectly.
4. Another variant of the false dilemma, the line-drawing fallacy, arises when discussing vague concepts: If you can't draw a line to demarcate the edge of a concept it is dismissed as hopelessly unclear.
1. Someone might bemoan the Constitution's protection against excessive bail, falsely arguing that we don't know where to draw the line between excessive and non-excessive amounts.
2. Some authors classify the line-drawing fallacy under the heading of slippery slope (see below), because it encourages the idea that one step in a given direction commits us to going all the way to the end. But bad reasoning about where to draw the line also is a clear case of a false dilemma.

5. One invokes a slippery slope when predicting that if one thing happens, or is permitted to happen, another thing (always a very undesirable thing) will eventually result.

1. The structure of the slippery slope fallacy is itself logically healthy. If A does imply B, and B is indeed absurd, or very undesirable, then you have produced an argument against A.
2. The slippery slope therefore makes good sense when A does imply or does lead to B. A society's small restrictions on the press can in fact lead to greater restrictions; so newspapers fight curbs on highly offensive language, not because they intent to print such language themselves, but in order to prevent being censored themselves in the future for something more ambiguous.
3. Such reasoning turns into fallacy when it rests on unfounded claims about whether A leads to B. It is not enough to point to some similarity between A and B; one must give a good reason for believing that A produces B.

6. One of the trickiest fallacies to detect is the one that misplaces the burden of proof. This fallacy occurs when one places the burden of proof on the wrong side of an issue, or places the burden of proof more heavily on one side than it should be.

1. The discussion of an issue can easily turn into a discussion of which side faces the greater burden of proof. It helps in such situations to have reasonable grounds for assigning the burden of proof properly.
2. All other things being equal, the greater burden of proof rests with someone whose claim has less initial plausibility (see Chapter ). Suppose one person claims that every even number is the sum of two prime numbers, while another person denies it. This claim will likely strike most people as implausible, so the first person faces the greater burden of proof.
3. All other things being equal, the greater burden of proof rests with someone making an affirmative claim, rather than with the one who is denying that claim.
1. Watch out especially for someone who defends an affirmative claim by throwing the burden onto the other side, calling a claim true simply because it has not been shown to be false.
2. This special type of burden-of-proof fallacy is called an appeal to ignorance.
4. Finally, consider special circumstances that shift the normal burden of proof. When there is a lot at stake (life, liberty), we should place a higher than usual burden of proof on claims that might cause harm.

7. The would-be defense of a claim that relies on the very claim it purports to prove is begging the question. This also gets called "circular reasoning," "starting too close to the conclusion," or (in certain cases, not always) "tautology."

1. Begging the question defeats the very idea of an argument, because premises ought to be statements that the other person already accepts, not the conclusion you are trying to get that person to accept.
2. Rarely does a question-begging bit of argument simply repeat the same words exactly -- that is too obvious -- so you should be alert for such disguises as appeals to synonyms. For example: "It's impossible to believe that space goes on infinitely, because that's inconceivable."