The term ad hominem is much misunderstood these days. In popular usage, it’s a personal attack leveled against someone you disagree with. Many never use the term without appending the word attack. “It’s nothing but an ad hominem attack,” they complain, as though an ad hominem is a nasty species of attack that automatically disproves every claim the user ever made. (And is it just me or does just about everybody employ “ad homnem attacks” even though they insist nobody else should?)
My aim here is to clarify a few things about the much misunderstood ad hominem.
First, the ad hominem is an argument, a bit of reasoning employed to support or counter a claim. Specifically, ad hominem looks to some trait an individual possesses (usually a flaw) to show that a claim is false (or, less commonly, that a claim is true). Ad hominem means “to the man,” and as a form of argument it is not inherently invalid or improper—or even impolite.