Two Paradoxes in the Theaetetus

Abstract

The announced aim of the Theaetetus is to define knowledge. After the definition of knowledge as perception has been rebutted, Socrates turns in the second major section of the dialogue to consider whether knowledge may be defined as true belief. This definition receives only brief scrutiny at the end of the section, the major part of which is concerned with a related line of thought. The definition requires, rightly, that if one knows what he believes, his belief must be true. How then to show that there can also be false belief, with which true belief may be contrasted? This paper considers two episodes in Socrates’ discussion of this question. Section I reconstructs a basic difficulty which Socrates sets out at the very beginning of his discussion in what can be called the first paradox at 188a-c; this is a difficulty not with falsity as such but with the falsity of identity judgements, and Socrates will return to it repeatedly as his discussion proceeds. Later parts of his discussion consider positive theories for how false belief can nonetheless occur. The first of these at 189bff.¹ is a theory of allodoxia so-called; Socrates’ scrutiny of this notion makes use of the basic difficulty presented in the first paradox, as part of an argument for the conclusion that all false belief whatsoever is impossible. Section II of this paper reconstructs the allodoxia proposal and its refutation, and considers its connection with the first paradox. The arguments themselves go together so closely that it seems worthwhile to consider them in separation from the remaining parts of Plato’s discussion.