A fallacy is a mistake in the logic of one’s thinking or communicating which leads to wrong conclusions. We as those who desire to be clear thinking and accurate about the properties of reality need to be familiar with fallacies as we are presented with them, in order to hone our ability to rightly appraise truth claims.
Definition: There are many flavors of ad hominem (“against the man”), but at its basic, this fallacy is committed when the argument is declared defeated not by attacking the argument itself but some irrelevant fact about the person making the argument.
Examples: “I believe abortion is morally wrong.” “Of course you’d say that, you’re a Christian.”
“You do not belong to my racial group so you clearly have no right to make an argument about crime within this group.”
“Well, you’re from Alabama, and they’re just a bunch of ignorant rednecks, so you can’t possibly understand.”
Recognizing the Fallacy: If someone’s response to your argument seems feelings-driven or coming from prejudice, placing the focus on the arguer and not the argument, you may be hearing an ad hominem fallacy.