An argumentum ad hominem (Latin: "argument against the man"), is a logical fallacy consisting of denigrating one's opponent or otherwise introducing irrelevant premises about one's opponent, instead of dealing with the flaws in the form and function of the opponent's argument. Note that the statement made in an ad hominem argument does not have to be false for this type of fallacy to have been committed; it just has to be irrelevant to the topic of the debate.
Classically, this fallacy is aimed at casting doubt on what a person is saying because of (imputed) flaws in the person's character, or circumstances peculiar to the person, that are unrelated to the matter at hand. Its usual structure is:
The ad hominem is objectionable and usually fallacious practice because:
That is, it has no bearing on the truth value of the other person's assertion.
The ad hominem fallacy can take several forms, the most common of which are personal abuse[4] and the introduction of an irrelevant circumstance.[4] Some debaters use the ad hominem attack pre-emptively, a technique known as poisoning the well.[5]
Example: Atheist scientist A might present arguments that there is no God. Opponent C might respond by stating that A is fat and should be able to use science to control his weight. This would be an example of the ad hominem fallacy.
In a special form of ad hominem that is closely akin to special pleading, a debater attempts to deflect criticism of himself by asserting that his opponent has the identical character flaw. This form is called tu quoque (Latin, "thou too") or "Whataboutism" (as in "What about [my opponent's identical character flaw]?"). The proverbial expression of this fallacy is "It takes one to know one" or "The pot calling the kettle black"[6]
Example: A liberal states that people should not vote for the Republican candidate because he is a racist. A conservative replies with "well you are also a racist so your argument doesn't count!". In this case, while the liberal may in fact be a racist, this doesn't preclude them from voting against a racist candidate.
The statement
might be considered an ad hominem attack on Wagner's music. It is true, and in some contexts might be a relevant comment. But if someone says it in order to suggest that Wagner was a bad composer, then it's an ad hominem attack, because whether some bad people liked his music is not a relevant comment on the quality of his music. Additionally, the Nazis' misdeeds had nothing to do with their ability to critique opera. However, even if a tone-deaf person, who is not a good judge of music, said he liked Wagner, it would still be an ad hominem attack to conclude Wagner is bad.
American Heritage Dictionary says:
Categories: [Logical Fallacies] [Liberal Traits] [Morality]