The Complete Idiot's Guide to Ad Hominem

by Eliezer Yudkowsky1 min read25th Nov 200815 comments


Personal Blog

Stephen Bond writes the definitive word on ad hominem in "the ad hominem fallacy fallacy":

In reality, ad hominem is unrelated to sarcasm or personal abuse.  Argumentum ad hominem is the logical fallacy of attempting to undermine a speaker's argument by attacking the speaker instead of addressing the argument.  The mere presence of a personal attack does not indicate ad hominem: the attack must be used for the purpose of undermining the argument, or otherwise the logical fallacy isn't there.


A: "All rodents are mammals, but a weasel isn't a rodent, so it can't be a mammal."
B: "You evidently know nothing about logic. This does not logically follow."

B's argument is still not ad hominem.  B does not imply that A's sentence does not logically follow because A knows nothing about logic.  B is still addressing the substance of A's argument...

This is too beautiful, thorough, and precise to not post.  HT to sfk on HN.