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ad hominem fallacy

Ad hominem is Latin for "to the man."  The ad hominem fallacy occurs when one asserts that somebody's claim is wrong because of something about the person making the claim. The ad hominem fallacy is often confused with the legitimate provision of evidence that a person is not to be trusted. Calling into question the reliability of a witness is relevant when the issue is whether to trust the witness. It is irrelevant, however, to call into question the reliability or morality or anything else about a person when the issue is whether that person's reasons for making a claim are good enough reasons to support the claim.

Good refutations of arguments try to undermine the accuracy, relevance, fairness, completeness, and sufficiency of reasons given to support a conclusion. One of the more common tactics of those who can't provide a good refutation of an argument is to divert attention away from the argument by calling attention to something about the person who made the argument. Rather than criticize a person’s premises or reasoning, one asserts something about the person’s character, associations, occupation, hobbies, motives, mental health, likes or dislikes.

The fallacy in the ad hominem is due to the irrelevant nature of the appeal made, not to its falsity. If what is said about the person is false, in addition to being irrelevant, two fallacies are committed, false premise and irrelevant premise.

Many people are seduced by ad hominem attacks. Sometimes, the appeal of the ad hominem is that it puts bad doctrines (i.e., those you disagree with) into the mouths of bad people (those you dislike). Sometimes, the ad hominem allows one to feel that one’s opponent is evil as well as stupid.

Attacking a person, rather than the person’s position or argument, is usually easier as well as psychologically more satisfying to those who divide the world into two classes of people—those who agree with them and are therefore good and right, and those who disagree with them and are therefore evil and wrong.

The ad hominem is attractive to lazy thinkers, who would rather ridicule or belittle a person than seriously examine an opposing viewpoint. The ad hominem is also a tactic of the clever manipulator of crowds, the experienced demagogue who knows how to play on the emotions of people and seduce them into transferring their attitude of disapproval for a person to disagreement with that person’s position.

One of the most frequent types of ad hominem attack is to attack the arguer's alleged motives rather than his evidence. For example, rather than taking apart an argument reason by reason, you claim that the arguer is just playing politics, is in the pockets of Big Pharma or the AMA, or is a government disinformation agent. One reader of my arguments against the 9/11 conspiracy argument had nothing to say about my argument but a lot to say about me. For example, he wrote: "you're probably an old guy and as we get older the brain just doesn't wanna have to deal with reality." Both claims may be true but neither of them is relevant to refuting my argument. This same fellow also wrote: "your views support a system that is completely corrupt because you have all your retirement money invested in that same system." And, instead of trying to show why I shouldn't trust any government report or claims on the issue, he wrote that my "'don't wanna question my government' view on 911 is scary quite frankly." This last assessment borders on a straw man attack, where one distorts another's position to make it easier to attack. This fellow seems to be suggesting that my real argument was that we should trust our government whenever it tells us something. Such a caricature of my arguments passes from being an attack on me into being an attack on a position I don't hold and did not defend.

When the irrelevant claims are negative, this fallacy is called poisoning the well. It's purpose seems two-fold: it gives a person a false sense of license to avoid producing any evidence of his own while giving the illusion of providing a rebuttal; and, it creates the false impression that the position you hold is held in good faith while the position you oppose is held by corrupt or compromised people like the one you pretend to be refuting.

See also Unnatural Acts: ad hominem, critical thinking mini-lesson 5 and Critical Thinking Workshop.

further reading

Browne, M. Neil & Stuart M. Keeley. Asking the Right Questions: A Guide to Critical Thinking (Prentice Hall, 1997).

Carroll, Robert Todd. Becoming a Critical Thinker - A Guide for the New Millennium (Boston: Pearson Custom Publishing, 2000).

Damer. T. Edward. Attacking Faulty Reasoning: A Practical Guide to Fallacy-Free Arguments 4th edition (Wadsworth Pub Co, 2001).

Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life, 8th edition (Wadsworth, 1997).

Moore, Brooke Noel. Critical Thinking (Mayfield Publishing Company, 2000).

Last updated 26-Dec-2013

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