Abstract

Plato's theory in the Republic has been a model for realist metaphysics. His text, however, is not easy to understand because his language is often only suggestive or metaphorical with the result that many different interpretations have flourished, especially in this century, and many questions have not been resolved. ;My dissertation is a new and up-to-date defense of a traditional reading of Plato's metaphysics in the Republic, focusing on three central problem areas: the degrees of reality, Plato's arguments for Forms, and mathematical intermediates. ;First, Plato distinguishes knowledge and opinion, and characterizes their objects as "what is" and "what is and is not," and some scholars have taken these to represent degrees of reality. This is a fundamental distinction for Plato; however, exactly what does he mean by "what is" and "what is and is not"? I shall argue that Plato primarily means "what exists" and "what exists and does not exist ", and that the distinction amounts to degrees of reality: being and becoming. ;Second, Plato uses two arguments for the existence of Forms: the Argument from Conflicting Appearances and the One-over-Many Argument . Exactly what are these arguments, and why does Plato use two, when one argument would seem to suffice? I shall argue that the two arguments can jointly generate Forms but taken separately each generates something short of Forms. They therefore function as one argument. ;Third, scholars have disagreed over whether Plato requires a separate metaphysical category for mathematical entities when he distinguishes two stages of knowledge in the Simile of the Line--noesis and dianoia. Granted that the objects of noesis are Forms, what are the objects of dianoia? I shall argue that they must be mathematical intermediates, while discussing related issues in the interpretation of this Simile. Without mathematical intermediates we could not understand the unique position of mathematics in Plato's educational program. ;The three problem areas are closed related, and my discussions will shed light to the basic tenets and logic of Plato's metaphysics