Fallacies Involving Credibility:
Ad Hominem

An ad hominem argument rejects or dismisses another person's statement by attacking the person rather than the statement itself.

There are many different forms of this fallacy, but all of them involve some attempt to avoid dealing with a statement logically, and in each case the method is to attempt to discredit the speaker by citing some negative trait. An ad hominem argument has the form:

X says p. X has some negative trait. Therefore, p is false.

This is a fallacy because the truth or falsity of the statement itself, or the strength of an argument for it, has nothing to do with the character, motives, or any other trait of the person who makes the statement or argument.

In its crudest form, the ad hominem fallacy involves nothing more than insults--calling one's opponent an idiot, slob, lowlife, airhead, fascist, pinko, nerd, fairy, bleeding heart, wimp, Neanderthal, and so on--using the rich vocabulary of abuse our language offers.

But the fallacy can also take more sophisticated forms. Let's look at two of them.

The Ad Hominen Fallacy of Tu Quoque

The Ad Hominen Fallacy of Poisoning the Well

Fallacies Involving Credibility

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