The Theaetetus is by common consent one of the classic texts in the history of epistemology. But would Plato himself understand and endorse this description? If “epistemology” were defined simply as “the study of epistēmē,” it would be easy to answer affirmatively, epistēmē being after all the official topic of the dialogue. But does Plato recognize any area of philosophy that would correspond to what we call epistemology?

For the later Platonist tradition, “logic” had come to constitute one of the three parts of philosophy, alongside ethics and physics; and cognition of truth (often under the rubric “the criterion of truth”) was in its turn recognized as a primary focus of “logic”. Hence Platonist schematizations had no trouble in classing the Theaetetus as a “logical” dialogue if they so wished. The epitome of Plato preserved by Stobaeus (Ecl. 2.49.8–25) is able to say that the goal of “becoming like god” is set out by Plato in the Timaeus from the point of view of physics (φυσικῶς), in the Republic from the point of view of ethics (ἠθικῶς), and in the Theaetetus from the point of view of logic (λογικῶς).