M.Sc., Ph.D. The Argument from Illusion in Gorgias’ treatise On What Is Not
Archai: Revista de Estudos sobre as Origens do Pensamento Ocidental January 19, 2026 Michael Bakaoukas
The argument from illusion, also known as the argument from perceptual relativity or conflicting appearances, has been used by philosophers from antiquity to the present to draw different conclusions. Plato used it to reveal weakness in human nature due to sight's liability to illusion. Aristotle's Protagoreans used it to deny the principle of contradiction. Sextus Empiricus used it to justify skepticism about belief and knowledge. Descartes used it to justify skepticism about the senses. Ayer used it to prove the existence of sense-data. This paper shows how Gorgias uses the argument from illusion in his treatise On What Is Not, relating it to problems in the philosophy of perception, a topic previously unaddressed in the literature.