Abstract

In the Protagoras, Socrates appears to affirm and defend a paradoxical doctrine: the unity of virtue. Plato scholars do not agree on how the doctrine should be understood. Some, following Vlastos (1972), take Socrates to hold that the virtues are biconditionally related, i.e. that anyone who has one of the virtues has them all. Others, following Penner (1973), take Socrates’ position to be that the names of the virtues all refer to the same thing, namely virtue. In this paper, I argue that both of these interpretations are mistaken: the main thesis of the Protagoras is, very simply, that each of the virtues is a kind of knowledge or wisdom.