Sophist

Webster's Dictionary of the English Language

·noun Hence, an impostor in argument; a captious or fallacious reasoner.

II. Sophist ·noun One of a class of men who taught eloquence, philosophy, and politics in ancient Greece; especially, one of those who, by their fallacious but plausible reasoning, puzzled inquirers after truth, weakened the faith of the people, and drew upon themselves general hatred and contempt.