1. a form of valid logical argument in which either (a) a premise is disproved by showing that it leads to a contradiction and is thus absurd or (b) a premise is indirectly proved by showing that its negation leads to a contradiction and is thus absurd.

2. in general language, a persuasive technique in which a position is presented in its most extreme or absurd form in order to discredit it. Such a move belongs more to sophistry than to logic. [Latin, literally: “reduction to the absurd”]