Theaetetus

Theaetetus asks what knowledge is through a conversation between Socrates and a gifted young student of mathematics. Their exchange is preserved inside a frame: Euclid tells Terpsion that he has a written record of the earlier discussion, which is then read aloud. This structure places the search for knowledge inside an act of memory, transcription, and transmission.

Socrates and Theaetetus test three major proposals. Knowledge may be perception; it may be true judgment; or it may be true judgment accompanied by an account. Each definition encounters difficulties. The discussion draws in Protagoras's claim that the human being is the measure of all things, theories of change, questions about error, and the problem of explaining what an adequate account would add to a correct judgment.

Socrates describes his method as intellectual midwifery. He does not claim to hand over a settled doctrine; he helps another person bring ideas into view and then examines whether they can survive questioning. That image offers a reading guide for the dialogue's inconclusive result. Failure to secure a definition is not presented as empty defeat, because Theaetetus becomes better able to distinguish what he knows from what he only assumes. Plato links philosophical progress to wonder, patience, and the willingness to discover that an attractive formula remains incomplete.