Introduction

On the basis of his discovery of the distinctive power of the soul, Theaetetus produces a new definition: knowledge is true opinion. This definition seems crucial to the examination of knowledge as Socrates understands it. Throughout the Platonic corpus he approaches the meaning of knowledge by distinguishing it from opinion. The very need for Socrates' inquiries arises out of a sense of the inadequacy of opinion. Socrates does not discover the distinction between the Way of Truth and the Way of Seeming. He does, however, acquire an insight regarding the imperfect separateness of the two realms. It is this insight that mandates the examination of opinion characteristic of Socratic inquiry.

Socrates' philosophizing retains a significant tie to opinion because it culminates in knowledge that is explicitly partial. Animated as it is by the incompleteness of opinion, Socratic inquiry does not fly wholly free of its bonds. The Theaetetus is paradigmatic in this regard, most obviously because of its culmination in explicit aporia (210b8–9). However, the dialogue as a whole also illuminates the manner in which opinion exerts its influence on inquiry, shaping its concerns, and even informing what it is we take knowledge to be.

Socratic philosophy appreciates the significance of opinion because it considers most deeply the implication of the partiality of knowledge. As reflective of our self-experience, the problem of knowledge actually asks how we can know only partially.