# Reductio Ad Absurdum in Argument

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2024-08-07 18:30:05

In argumentation and informal logic, reductio ad absurdum (RAA) is a method of refuting a claim by extending the logic of the opponent's argument to a point of absurdity. Also known as the reductio argument and argumentum ad absurdum.

Similarly, reductio ad absurdum may refer to a type of argument in which something is proved to be true by showing that the opposite is untrue. Also known as indirect proof, proof by contradiction, and classical reductio ad absurdum.

As Morrow and Weston point out in A Workbook for Arguments (2015), arguments developed by reductio ad absurdum are frequently used to prove mathematical theorems. Mathematicians "often call these arguments 'proofs by contradiction.' They use this name because mathematical reductio arguments lead to contradictions--such as the claim that N both is and is not the largest prime number. Since contradictions can't be true, they make for very strong reductio arguments."

Like any argumentative strategy, reductio ad absurdum can be misused and abused, but in itself it is not a form of fallacious reasoning. A related form of argument, the slippery slope argument, takes reductio ad absurdum to an extreme and is often (but not always) fallacious.