Dialogues of Plato, Vol. 4 (Parmenides, Theaetetus, Sophist)

(7) We are now able to determine the composition of the perfect life. First, we admit the pure pleasures and the pure sciences. Secondly, we admit the "impure" sciences, but not the impure pleasures. We must next discover what element of goodness is contained in this mixture. There are three criteria of goodness: beauty, symmetry, and truth. These are clearly more akin to reason than to pleasure and will enable us to rank them in the scale of good. First in the scale is measure; the second place is assigned to symmetry; the third to reason and wisdom; the fourth to knowledge and true opinion; the fifth to pure pleasures; and here the Muse says, "Enough."

"Bidding farewell to Philebus and Socrates," we may now proceed to consider the metaphysical conceptions presented to us. These are: (I) the paradox of unity and plurality; (II) the table of categories or elements; (III) the kinds of pleasure; (IV) the kinds of knowledge; (V) the conception of the good; (VI) the relation of the Philebus to the Republic and other dialogues.

I. The paradox of the "one and many" originated in the restless dialectic of Zeno, who sought to prove the absolute existence of the "one" by showing the contradictions involved in admitting the existence of the "many" (cp. Parm. 128 ff.). Zeno illustrated the contradiction with well-known examples taken from outward objects. But Socrates seems to suggest that the time has arrived for discarding these hackneyed illustrations; such difficulties had long been solved by common sense (solvitur ambulando original: "solved by walking"—a reference to Diogenes the Cynic, who refuted arguments against motion by simply walking), as the mere familiarity with the fact was a sufficient answer. He will leave such things to the Cynics and Eristics; the youth of Athens may discourse of them to their parents. To no rational man could the circumstance that the body is one, but has many members, be any longer a stumbling block.

Plato’s difficulty seems to begin in the region of ideas. He cannot understand how an absolute unity, such as the Eleatic "being," can be broken up into a number of individuals, or be both in and out of them at once. Philosophy had so deepened or intensified the nature of "one" or "being" through the thoughts of successive generations that the mind could no longer imagine "being" as in a state of change or division. To us, it is easy to say that the verb "is" is merely a copula, or that "unity" is a mere unit; but to the Greeks, such an analysis involved the same kind of difficulty as the conception of God existing both in and out of the world.