Gorgias (gôr´jēəs), c.485–c.380 BC, Greek Sophist. From his native city, Leontini, Sicily, he was sent as an ambassador to Athens, where he settled to teach and practice rhetoric. Gorgias pursued the negative implications of the Eleatic school and asserted: (1) Nothing exists; (2) If anything does exist, it cannot be known; (3) If it can be known, the knowledge of it cannot be communicated. Objective truth being thus impossible, there remains only the art of the Sophists, persuasion. Such arguments undermined the foundations of polytheism and led to open challenges of current moral standards. His challenge to speculative thought stimulated a more sophisticated approach to the problems of philosophy. A dialogue of Plato's bears his name.