Published online by Cambridge University Press: 23 December 2013
Towards the close of Book V of the Republic Plato tells us that the true philosopher has knowledge and that the objects of knowledge are the Forms. By contrast, the ‘lovers of sights and sounds’, he tells us, have no more than belief, the objects of which are physical particulars. He then goes on to present us with some very radical-sounding assertions about the nature of these physical particulars. They are bearers of opposite properties, he says, in so thorough-going a manner that we cannot say of them that they are nor that they are not: they lie somewhere between being and utter non-being.
This passage of the Republic (475–80) still awaits an agreed interpretation and I want to suggest as a reason for this that it is usually interpreted in isolation. I will argue that it becomes easier to understand when seen against the background of Plato's developing thought. To be more precise, it makes sense when taken as a rejection by Plato of one of his earlier beliefs: namely, a doctrine of essentialism to be found in the Phaedo.
The greater part of this paper then will be an attempt to show that Republic V is a rejection of the Phaedo's doctrine of essences. Its concluding part will try to explain why that doctrine was rejected.