Definition of petitio principii in English:

petitio principii

Pronunciation /pəˌtiSHēō prinˈsipēˌī/ /pəˌtɪʃioʊ prɪnˈsɪpiˌaɪ/


  • A fallacy in which a conclusion is taken for granted in the premises; begging the question.

    ‘This, with great respect, is a petitio principii - reasoning which assumes the very thing which requires decision.’
    • ‘Here I shall simply observe that the objection is a gross petitio principii.’


Latin, literally ‘laying claim to a principle’.