In 365 BC, at the gates of the city Megara, Eucleides, and Terpsion hear a slave read Eucleides’ memoir of a discussion that took place in 399 BC. In this discussion, Theaetetus, a student, is introduced to Socrates by his teacher, Theodorus.
Socrates asks Theaetetus what knowledge is, spurring the rest of the conversation of the dialogue. Theaetetus responds to Socrates' question by naming traditional academic examples of knowledge: geometry, arithmetic, astronomy. Socrates tells Theaetetus that examples are not the same as a definition, and Theaetetus agrees. Socrates then offers to help Theaetetus define knowledge by comparing himself to a midwife: his duty is to help guide others to give birth to the knowledge they possess.
After Socrates’ analogy, Theaetetus offers a more acceptable definition of knowledge: “Knowledge is perception” (151d-e). A discussion of perception and relativism entails, wherein Socrates ultimately deems perception and knowledge to be different things.
Then, Theaetetus offers a third definition of knowledge, wherein knowledge is defined as “true belief” (186b4-8). Socrates asks Theaetetus what a false belief is, and the two attempt to come up with a false belief. They try five times, and each time they fail to conjure a false belief. Socrates then dismisses Theaetetus’ new definition on the basis that an accidental true belief cannot be considered “knowledge.”
Theaetetus refines his definition by claiming that knowledge is “true belief with an account (logos)” (201c-d). Theaetetus and Socrates discuss what “logos” means, and ultimately, the two are left without completing the task. The dialogue ends with Socrates telling Theaetetus that all the two of them have produced were “wind-eggs.” He leaves to go to trial at court.
