Abstract

Commentators in antiquity took Plato to have a system of categories which they compared with Aristotle's. This work begins by exploring the genera of absolute and relative in Plato's dialogues. In addition, Aristotle alleged that Plato had a special argument for the existence of Forms corresponding to relative terms. Yet the argument which Alexander purports to reproduce from Aristotle's lost Peri Ideon does not obviously summarize any argument found in the Platonic dialogues. The last four chapters of the dissertation attempt to isolate genuinely Platonic reasons for supposing that there are Forms for pros ti terms and to show that these reasons to do generalize to Forms for kath hauto terms. ;In order to resolve these questions I first turn to the very early dialogues. I offer a view about what sort of thing Socrates is looking for when he asks a question like, "What is piety?" and isolate some constraints on the adequacy of any answer. These constraints raise special problems for answers to "what is X?" questions when X is a relative term. These problems, together with certain other background assumptions, give Plato a reason to think that the sort of being which corresponds to the answer to a "What is X?" question is very unlike sensible things. Because 'beauty,' for instance, is a pros ti term, it will both hold and not hold for sensibles depending on how the predicate is completed. In the Phaedo he is led to the hypothesis that the accounts of relative terms are about separated Forms. Thus, Plato does have special reasons for thinking that there are Forms for relative terms--reasons that are not immediately applicable to kath hauta terms