Plato

Plato of Athens

At the height of his fame, with a theory of reality already in circulation that would shape the next two thousand years, Plato sat down and wrote a dialogue designed to take it apart. In the Parmenides a young Socrates lays out the doctrine for which Plato is still famous, that beyond our shifting world of particular things stand the Forms, perfect and eternal originals, and the aged philosopher Parmenides proceeds, with terrible patience, to show that the theory cannot stand as stated. The young Socrates has no reply. The single most damaging attack on the Theory of Forms anywhere in antiquity was composed by the man who invented it. That is the Plato this room is built around: not the serene dogmatist of two worlds the textbooks hand down, but a restless mind that spent its last decades interrogating its own best idea harder than any opponent dared to. The dialogues most readers meet first, the ones carried by the character of Socrates, have a room of their own here. This one follows the late Plato, where Socrates falls quiet and a harder, self-correcting philosophy takes the floor.

What the Forms were for. To feel the force of the self-criticism you have to see why Plato needed the Forms at all. He had taken from Heraclitus the unsettling thought that the sensible world never holds still, and from Socrates the demand that we be able to say what justice or courage or beauty really is. Put the two together and a problem opens. Knowledge needs a fixed object, something that stays put long enough to be known and is exactly what our concept says it is. But nothing in this world qualifies. Every river is changing as you name it; no drawn circle is perfectly circular; no act is justice itself, only more or less just, and only for a while. So the true objects of knowledge, Plato argued, cannot be the things we see. They must be the Forms: Circle itself, Justice itself, and at the summit the Good itself, perfect and changeless originals that the passing particulars imitate without ever matching. The allegory of the cave dramatizes the stakes. We sit chained, taking flickering shadows for the whole of reality, and philosophy is the steep and painful climb out into the light, where the originals, and at last the sun that lights them, can finally be seen.

The third man. Then, in the Parmenides, Plato turns the knife on himself. If every just thing is just by sharing in the one Form of Justice, the old Parmenides asks, then consider Justice together with all the just things: are they not now a new group all having justice in common, which must therefore share in a further Form, and that one in another, without end? The objection is known as the third-man regress, and it is only the first. How does a particular "share in" a Form, exactly, what is that relation? And if the Forms are truly sealed off in their perfection, separate from our world, how could we down here ever come to know them? The young Socrates cannot answer any of it, and the old man tells him, not unkindly, that he has tried to define the Forms before training himself in the harder art of argument. What Plato is doing is unmistakable once you have read the Socratic dialogues: he is running Socrates's own method, the elenchus, against his own central doctrine, dragging into the light the contradictions hidden inside a position he loves, and refusing to spare it because it is his. It is the most honest thing in the corpus.

Carving at the joints. Plato's response to his own attack was not to give up the Forms but to change the way he handled them. In the late dialogues the lonely, self-sufficient Forms of the middle period give way to a web. The Sophist works out what Plato calls the communion of kinds, the way the most general kinds, being and sameness and difference and rest and motion, combine with and exclude one another in fixed patterns, so that to understand anything is to map where it sits in that network rather than to glimpse it alone. And the flash of direct intuition the cave had promised is replaced by a method any patient person can run: division, diairesis, in which you take a broad kind, cut it cleanly in two, follow the half that holds your quarry, and cut again, until the thing is fenced off by everything it is not. Carve nature at its joints, he says, not hacking like a clumsy butcher but cutting where the natural divisions already lie. The same machinery dissolves the ancient riddle that had stumped Parmenides, how we can even speak of what is not. To say a thing is not tall, the Sophist shows, is not to point at nothing; it is to mark a difference. Non-being is simply otherness, and the moment you see that, the paralysis lifts.

The made cosmos. The Timaeus turns the Forms outward onto the whole universe. A divine craftsman, the Demiurge, builds the cosmos the way any craftsman builds, by looking to a model and copying it, and the model is the eternal Forms; he takes a formless medium, the receptacle, and stamps it into an ordered world, fashioning even the four elements out of geometric solids, so that physics becomes a kind of sacred geometry. From this dialogue comes one of the most haunting sentences in philosophy: time, Plato writes, is the moving image of eternity (Timaeus 37d), the nearest a changing world can come to the changeless, eternity set turning. For most of the Latin Middle Ages a single fragment of the Timaeus was nearly the only Plato anyone could read, and its vision of a mathematically ordered cosmos ran straight down the centuries; Kepler was still building models of the heavens out of Plato's five solids in 1596. It is the dialogue where the theory of Forms stops being an account of knowledge and becomes an account of how a world gets made.

The second-best city. No part of Plato has been more caricatured than the politics. The Republic, with its philosopher-kings and its censored poets and its guardians who hold wives and property in common, was read in the twentieth century, by Karl Popper most loudly, as a blueprint for the closed and total state. But the Republicannounces itself as a city built in speech, a thought-experiment whose real subject is justice in the individual soul, and Plato knew the difference between a model and a plan. In his longest and last work, the Laws, the old philosopher designs a city meant actually to be lived in, and it is a startlingly different place. There is no philosopher-king; there are laws, carefully written and even more carefully explained, because Plato now holds that a free people must be persuaded and not merely commanded. There is private property, and there are families, and there is a mixed constitution balancing competing powers against one another. The utopian had become, in the end, a realist about what human beings are actually like and how much order they will bear. The man the cartoon calls a totalitarian spent his final energies writing the case for the rule of law.

What he would not write down. Even the dialogues, it seems, hold something back. Aristotle, who spent twenty years in the Academy, reports that Plato once gave a public lecture grandly titled "On the Good," and that the audience arrived expecting practical wisdom about happiness and wealth and health and instead got an evening of mathematics, the One and the Indefinite Dyad, ultimate principles he is said to have taught inside the school but never set down in a book. Whether these "unwritten doctrines" are the secret system at the core of Platonism or a minor oral tradition is still genuinely disputed. But the reticence fits the man. In the Phaedrus he has Socrates argue that writing is a counterfeit of living thought, that a written page "goes on telling you the same thing forever" and cannot answer a question or defend itself or know whom it should address. So Plato wrote dialogues and never treatises, staging philosophy as a conversation among living voices rather than delivering conclusions in his own, precisely so the thinking could not harden into a creed. The room reads these late dialogues in Benjamin Jowett's translations, cited by the old Stephanus page; but Plato would want it understood that the page is the beginning of the work and not the end.

Whitehead said that the safest general characterization of the European philosophical tradition is that it consists of a series of footnotes to Plato, and the line is an exaggeration only in the way the best jokes are. Aristotle built his philosophy by arguing with the Forms; the Academy Plato founded eventually turned skeptical and decided the dialogues taught doubt rather than doctrine; Plotinus made the bruising Parmenides the center of a new mysticism of the One; Augustine moved the Forms into the mind of God; the Renaissance reopened when Ficino put the whole of Plato into Latin. What every one of them inherited was not a closed system but an open and self-questioning one, a body of work that carries its own sharpest objections inside it. That, in the end, is the most useful thing Plato models, and it is rarer than any doctrine: the discipline of taking the idea you most want to be true and attacking it harder than your opponents ever will. He did it to the Forms in the Parmenides, in public, at the height of his powers. Twenty-four centuries of philosophy have been trying to live up to the example.