A Beginner's History of Philosophy, Vol. 1: Ancient and Mediæval Philosophy

by Herbert Ernest Cushman

1. The Earlier Draft of Ideas.

(a) The Number of Ideas is infinite.

(b) The Relation of Ideas to Physical Things is similarity. The Ideas on their side are spoken of as having a “presence” in physical things, but never fully appearing in them; the physical phenomena on their side are spoken of as “participating” in the Ideas.

(c) The Ideas are Related to One Another logically, as genera to species, but they are only roughly classified by Plato.

2. The Later Draft of Ideas—Plato’s Final Statement.

(a) The Number of Ideas is limited to those of worth, mathematical relations, and nature-products, but Plato never arrived at any definite selection.

(b) The Relation of Ideas to Physical Things is teleological. The Ideas are the ideal or purposeful ends of physical objects.

(c) The Ideas are Related to One Another teleologically. The Idea of the Good stands at the head, and is the purposeful end of all the other Ideas.

Comparison of the Two Drafts of Ideas in More Detail.

1. The Number of Ideas in the Earlier and Later Drafts compared. When Plato first presented the Theory of Ideas to himself, he conceived their number to be infinite. There are Ideas of everything that isthinkable. There are as many as there are class concepts, as there are qualities of things in the universe, as there are common nouns in the language. But it was pointed out to Plato that he had only reproduced and paralleled in the immaterial world what exists in the material world; that such a theory did not solve, but only doubled our difficulties. Then there were technical difficulties in the conception of the Ideas of everything—of things, qualities, relations,—good, bad, and indifferent. But what probably appealed to him most cogently was the raillery to which he found his theory subjected (see Parmenides), that he as a Greek could think of ugly Ideas, like hair and filth, as real. The result was that in the later drafting of his theory the number of qualities worthy to be called Ideas becomes very much limited. Plato makes the elimination from no avowed principle except that of worth, because as a Greek it was absolutely repellent to him to regard anything as real except worth. Consequently in his later dialogues he speaks of (1) Ideas having an inherent value, like the Good and the Beautiful, (2) Ideas corresponding to nature products, (3) Ideas of mathematical relations. Norms of value thus take the place of class-concepts, and in his selection of Ideas his choice is determined more and more by their moral worth.