pe·ti·ti·o prin·ci·pi·i 
(pə-tĭshē-ō′ prĭn-sĭpē-ē′, -ē-ī′)
(pə-tĭshē-ō′ prĭn-sĭpē-ē′, -ē-ī′)n.
Logic
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.]