petitioprincipii

pe·ti·ti·o prin·ci·pi·i (pə-tĭshʹē-ō' prĭn-sĭpʹē-ē', -ē-ī') n. Logic

The fallacy of assuming in the premise of an argument that which one wishes to prove in the conclusion; a begging of the question.

  [Medieval Latin petītiō prīncipiī: Latin petītiō, request + Latin prīncipiī, genitive of prīncipium, beginning.]

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