petitio principii

noun pe·ti·tio prin·ci·pii \pə-ˈtē-tē-ˌō-(ˌ)priŋ-ˈki-pē-ˌē\

Definition of PETITIO PRINCIPII

: a logical fallacy in which a premise is assumed to be true without warrant or in which what is to be proved is implicitly taken for granted

Medieval Latin, literally, postulation of the beginning, begging the question

First Known Use: circa 1531

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