tu quoque fallacy

(LOGIC) a logical fallacy in which a person defends against an allegation by accusing an adversary of doing the same thing. It's a classic douchebag move because it implies that the speaker has a RIGHT to be a douchebag, by virtue of the fact that someone ELSE is being a douchebag. From Latin, for "you, too." WHY IT'S BAD Suppose A is accused of terrorism. He reacts by accusing B, his enemy, of terrorism. Now, it's possible (but unlikely) that A actually chose this argument knowing he was totally innocent. More likely he wants to claim that his terrorism is PROVOKED. In effect, he's saying, "I have to do this, or I'm entitled to do this, because B did it first." First, as logic it's a red herring. But what makes it douchebaggery rather than just another wartime propaganda tactic, is that it's MORALLY irrelevant as well as LOGICALLY irrelevant. The victims of terrorism almost never have any material control over either perpetrator ever.