Reductio ad absurdum, Latin for "reduction to the absurd", traceable back to the Greek ἡ εις άτοπον απαγωγη (hê eis átopon apagogê), "reduction to the impossible", often used by Aristotle, also known as an apagogical argument, reductio ad impossibile, or proof by contradiction, is a type of logical argument where one assumes a claim for the sake of argument, derives an absurd or ridiculous outcome, and then concludes that the original assumption must have been wrong, as it led to an absurd result. It makes use of the law of non-contradiction - a statement cannot be both true and false. In some cases it may also make use of the law of excluded middle - a statement must be either true or false.