a third.) What is Plato’s response to this and other objections to his theory? He says in the Parmenides that we must continue to affirm the existence of such objects, for language and thought require them; but instead of responding directly to the criticisms, he embarks on a prolonged examination of the concept of unity, reaching apparently conflicting conclusions about it. Whether these contradictions are merely apparent and whether this treatment of unity contains a response to the earlier critique of the Forms are difficult matters of interpretation. But in any case it is clear that Plato continues to uphold the existence of unchanging realities; the real difficulty is whether and how he modifies his earlier views about them. In the Timaeus, there seem to be no modifications at all – a fact that has led some scholars to believe, in spite of some stylometric evidence to the contrary, that this work was written before Plato composed the critique of the Forms in the Parmenides. This dialogue presents an account of how a divine but not omnipotent craftsman transformed the disorderly materials of the universe into a harmonious cosmos by looking to the unchanging Forms as paradigms and creating, to the best of his limited abilities, constantly fluctuating images of those paradigms. The created cosmos is viewed as a single living organism governed by its own divinely intelligent soul; time itself came into existence with the cosmos, being an image of the timeless nature of the Forms; space, however, is not created by the divine craftsman but is the characterless receptacle in which all change takes place. The basic ingredients of the universe are not earth, air, fire, and water, as some thinkers held; rather, these elements are composed of planes, which are in turn made out of elementary triangular shapes. The Timaeus is an attempt to show that although many other types of objects besides the Forms must be invoked in order to understand the orderly nature of the changing universe – souls, triangles, space – the best scientific explanations will portray the physical world as a purposeful and very good approximation to a perfect pattern inherent in these unchanging and eternal objects.
But Forms do not play as important a role in the Philebus, a late dialogue that contains Plato’s fullest answer to the question, What is the good? He argues that neither pleasure not intelligence can by itself be identified with the good, since no one would be satisfied with a life that contained just one of these but totally lacked the other. Instead, goodness is identified with proportion, beauty, and truth; and intelligence is ranked a superior good to pleasure because of its greater kinship to these three. Here, as in the middle dialogues, Plato insists that a proper understanding of goodness requires a metaphysical grounding. To evaluate the role of pleasure in human life, we need a methodology that applies to all other areas of understanding. More specifically, we must recognize that everything can be placed in one of four categories: the limited, the unlimited, the mixture of these two, and the intelligent creation of this mixture. Where Forms are to be located in this scheme is unclear. Although metaphysics is invoked to answer practical questions, as in the Republic, it is not precisely the same metaphysics as before.
Though we naturally think of Plato primarily as a writer of philosophical works, he regards the written word as inferior to spoken interchange as an instrument for learning and teaching. The drawbacks inherent in written composition are most fully set forth in the Phaedrus. There is no doubt that in the Academy he participated fully in philosophical debate, and on at least one occasion he lectured to a general audience. We are told by Aristoxenus, a pupil of Aristotle, that many in Plato’s audience were baffled and disappointed by a lecture in which he maintained that Good is one. We can safely assume that in conversation Plato put forward important philosophical ideas that nonetheless did not find their way into his writings. Aristotle refers in Physics IV.2 to one of Plato’s doctrines as unwritten, and the enigmatic positions he ascribes to Plato in Metaphysics I.6 – that the Forms are to be explained in terms of number, which are in turn generated from the One and the dyad of great and small – seem to have been expounded solely in discussion. Some scholars have put great weight on the statement in the Seventh Letter that the most fundamental philosophical matters must remain unwritten, and, using later testimony about Plato’s unwritten doctrines, they read the dialogues as signs of a more profound but hidden truth. The authenticity of the Seventh Letter is a disputed question, however. In any case, since Aristotle himself treats the middle and late dialogues as undissembling accounts of Plato’s philosophy, we are on firm ground in adopting the same approach. See also ARISTOTLE , COMMENTARIES ON PLATO , NEOPLATONISM , SOCRATE. R.Kr.