Argumentum ad hominem

Latin for: Argument at the man

An "ad hominem" attack is one against a person or group who has stated an idea, rather than the idea itself. Usually, an argumentum ad hominem is attacking a source or authority for information.

As Fallacy Files says, "Argumentum ad hominem also occurs when someone's arguments are discounted merely because they stand to benefit from the policy they advocate."

An argument can be valid or invalid no matter who makes it. A special case of this general principle is that in court, known perjurers may have an impossibly difficult burden of proof to carry, and in fact their testimony may be ruled inadmissible, especially if the perjury occurs during the case at hand.

Ad hominem arguments may often be restated in better form, as changing "You're a socialist." into "What you have expressed is socialist dogma." It still needs work, since there may not be a clear relationship between the former ad hominem target's words and socialist dogma, and there is a need to overcome the burden of proving socialist dogma to be invalid, since some may find socialist dogma to be wholly reasonable.

A special case of ad hominem is the ad hominem tu quoque, in which an argument is attacked because its proponents fail (or failed in the past) to show full adherence to it themselves.

[Updated 7/15/07 for formatting, conversion to search links, and the like.]