An ad hominem (Latin for "to the man" or "to the person"[1]), short for argumentum ad hominem, is a general category of fallacies in which a claim or argument is rejected on the basis of some irrelevant fact about the author of or the person presenting the claim or argument.[2] Fallacious Ad hominem reasoning is normally categorized as an informal fallacy,[3][4][5] more precisely as a genetic fallacy,[6] a subcategory of fallacies of irrelevance.[7] Ad hominem reasoning is not always fallacious, for example, when it relates to the credibility of statements of fact.
Ad hominem arguments are the converse of appeals to authority, and may be used in response to such appeals.