Introduction

What is knowledge? That single question is the subject of the Theaetetus, and the starting point of Western epistemology. Socrates and the gifted young mathematician Theaetetus test three definitions in turn: knowledge is perception, knowledge is true belief, knowledge is true belief with an account. Along the way Socrates describes himself as a midwife of souls and makes his famous critique of Protagoras' claim that man is the measure of all things. The dialogue reaches no conclusion, but leaves the question clearer than it had ever been.