Third man argument

Third Man argument

Plato's theory of Forms—as it is presented in such dialogues as the Phaedo, Republic and the first part of the Parmenides—seems committed to the principles listed below, where "F" stands for any property for which we posit a Form (forma being a Boethian translation for the Ancient Greek: εἶδος, romanized: eîdos, which latter word originally meant "appearance, shape"). Plato, in the Parmenides, uses the example "greatness" (μέγεθος) for F-ness; Aristotle uses the example "man". In what follows, the argument will be illustrated using μέγας (megas, "great"); however, the reasoning remains valid for any choice of F.