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reductio ad absurdum

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(Latin, reduction to absurdity)

The process of reasoning that derives a contradiction from some set of assumptions, and concludes that the set as a whole is untenable, so that at least one of them is to be rejected. Formally, if {A1 … An} ├(B & ¬B), then {A1 … An−1} ├¬An.

Subjects: Philosophy

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