In ancient Greece, one of a group of 5th-century BC itinerant lecturers on culture, rhetoric, and politics. Skeptical about the possibility of achieving genuine knowledge, they applied bogus reasoning and were concerned with winning arguments rather than establishing the truth. Plato regarded them as dishonest and sophistry came to mean fallacious reasoning.

A philosopher who seeks paradoxes, or one who advances ideas that seem inconsistent with common sense.