A Fallacy in Plato's Republic?

Abstract

AN ARTICLE published by Professor David Sachs in the Philosophical Review' offers a scholarly and penetrating interpretation of some of Plato's views. Indeed, on some matters I believe that it makes a contribution to our understanding of Plato. In this discussion, however, I will be mainly concerned with Sachs's attribution of a fallacy to Plato, as stated in the title of his article. I agree that there is a gap in the argument, but a gap is a lacuna and a lacuna is not a fallacy. Mathematicians often skip steps in an inference, thinking them obvious. I take it that a fallacy is invalid inference: it exists when a proposition is inferred from a premise when, in fact, it is not entailed by it. I hope to prove that Sachs has not made his point; more particularly, that he has failed to prove that Plato's conclusion could not logically follow from his premise. Sachs makes a vital distinction which helps clear up a confusion in Plato's argument. Sachs insists that we must keep apart two questions: (a) Does entail happiness? (b) Does entail vulgar or conventional morality ((pOPTLKO; Republic, 444e 3)? He rightly insists that an answer to the first questions has no bearing on the answer to the second. In other words, were we to succeed in proving that a just man will be happy, we should still not know that he will be conventionally moral. A very important use of justice by Plato is the rendering to every man his due. This is the refrain running throughout Republic I; it is the ordinary, the conventional meaning of justice; it is the conception of as a social virtue. But in Book IV, Plato comes up with a different and unconventional definition ofjustice; it is, so far as I know, unique with Plato among Greek philosophers, and indeed Sachs calls it Platonic justice. This is the view of as (a) the state of the soul in which no part of the soul interferes with the functioning of the other parts-call it the principle of nonintervention-and (b) the state of the soul in which the various parts are working in mutual harmony and friendship (4ilOvota,, Pbnata; 35id 3; 433e 2-4). Should anyone wonder whether there is any significant difference between