The dialogue form in which Plato writes is more than a mere literary device; it is instead an expression of Plato’s understanding of the purpose and nature of philosophy. For Plato, philosophy is a process of constant questioning, and questioning necessarily takes the form of dialogue. Near the end of the Phaedrus, Socrates expresses his reservations about written texts, worrying that people will cease to think for themselves when they have someone else’s thoughts written out in front of them. Plato took it upon himself to write his thoughts down anyway, but he was careful not to write them in such a way that we could easily assimilate his thoughts rather than thinking for ourselves. Many of the dialogues reach no definite conclusions, and those that do generally approach those conclusions by casting doubts and examining possible counterarguments. Plato cannot be there in person to share his thoughts with us, but he wants to ensure that we think through them ourselves.
In keeping with this emphasis on dialogue form, Plato develops an increasingly complex conception of dialectic, or logical argument, as the engine that drives philosophical investigations. In the early dialogues, dialectic consists of Socrates cross-examining and refuting his interlocutors until he brings them to a state of perplexity, or aporia. Beginning with the Meno, Plato recognizes that dialectic can lead people not only to recognize their errors but also to positive discoveries, as Socrates does with the slave boy in the Meno. Plato is sufficiently impressed with the possibilities of the dialectic that, in the Republic, he makes it the highest achievement of his rigorous education program. The Phaedrus introduces a more systematic version of the dialectic, seeing it as a matter of “division and generalization,” whereby we analyze concepts so as to understand the precise relations between them. This process of division and generalization becomes increasingly sophisticated throughout Plato’s works, and we witness advanced versions of it in the Parmenides and the Sophist.
Plato considers the sophists to be one of the primary enemies of virtue, and he is merciless in his attacks on them. The sophists, who were relatively new in Plato’s day, were a class of itinerant teachers who instructed young statesmen in the arts of rhetoric and debate for a fee. They taught that values are relative, so that the only measure of who is right is who comes out on top. Their teachings capitalized on a void left by the ancient myths and religion, which were falling out of fashion as Greek civilization moved toward a more rational worldview. The old values were losing their relevance, and there were no new values to replace them. Plato could see the danger this moral relativism posed for the state and for the people who lived in it, and his attacks on the sophists show up their hollow bravado that so many took for wisdom. Plato’s Theory of Forms, and the whole enterprise of the Republic, can be read as an attempt to find a solid grounding for moral values in rational principles.
The Theory of Forms maintains that two distinct levels of reality exist: the visible world of sights and sounds that we inhabit and the intelligible world of Forms that stands above the visible world and gives it being. For example, Plato maintains that in addition to being able to identify a beautiful person or a beautiful painting, we also have a general conception of Beauty itself, and we are able to identify the beauty in a person or a painting only because we have this conception of Beauty in the abstract. In other words, the beautiful things we can see are beautiful only because they participate in the more general Form of Beauty. This Form of Beauty is itself invisible, eternal, and unchanging, unlike the things in the visible world that can grow old and lose their beauty. The Theory of Forms envisions an entire world of such Forms, a world that exists outside of time and space, where Beauty, Justice, Courage, Temperance, and the like exist untarnished by the changes and imperfections of the visible world.
Plato’s conception of Forms actually differs from dialogue to dialogue, and in certain respects it is never fully explained, so many aspects of the theory are open to interpretation. Forms are first introduced in the Phaedo, but in that dialogue the concept is simply referred to as something the participants are already familiar with, and the theory itself is not developed. Similarly, in the Republic, Plato relies on the concept of Forms as the basis of many of his arguments but feels no need to argue for the validity of the theory itself or to explain precisely what Forms are. Commentators have been left with the task of explaining what Forms are and how visible objects participate in them, and there has been no shortage of disagreement. Some scholars advance the view that Forms are paradigms, perfect examples on which the imperfect world is modeled. Others interpret Forms as universals, so that the Form of Beauty, for example, is that quality that all beautiful things share. Yet others interpret Forms as “stuffs,” the conglomeration of all instances of a quality in the visible world. Under this interpretation, we could say there is a little beauty in one person, a little beauty in another—all the beauty in the world put together is the Form of Beauty. Plato himself was aware of the ambiguities and inconsistencies in his Theory of Forms, as is evident from the incisive criticism he makes of his own theory in the Parmenides.
In essence, the Theory of Forms represents Plato’s attempt to cultivate our capacity for abstract thought. Philosophy was a relatively new invention in Plato’s day, and it competed with mythology, tragedy, and epic poetry as the primary means by which people could make sense of their place in the world. Like philosophy, art and mythology provide concepts that help us to understand ourselves, but art and mythology do so by appealing to our emotions and desires. Philosophy appeals to the intellect. The Theory of Forms differentiates the abstract world of thought from the world of the senses, where art and mythology operate. Plato also argued that abstract thought is superior to the world of the senses. By investigating the world of Forms, Plato hopes to attain a greater knowledge.
In the Republic and the Phaedrus, Plato describes the soul as divided into three parts, labeled appetitive, spirited, and rational. He offers this division partly as a way of explaining our psychological complexity and partly to provide a justification for philosophy as the highest of all pursuits, because it corresponds to the highest part of the soul—the rational part. We might feel the pull of these three parts when presented with a bowl of ice cream, a roast we accidentally overcooked ourselves, and a healthy salad. The appetitive part of our soul will crave the sensual pleasures it will derive from the ice cream, the spirited part of our soul will want to eat the charred roast out of a sense of pride in our own work, and the rational part of our soul will want to eat the salad as the healthiest of the three options. In proposing a tripartite soul, Plato acknowledges and seeks to explain the fact that we all experience inner conflict from time to time. We would be justified in seeing this theory as the starting point for psychology. However, Plato’s theory seeks not only to explain inner conflict but also to present the rational part of the soul as superior. Philosophy is essentially the practice of refining and foregrounding our rationality.
In both the Republic and the Laws, Plato identifies education as one of the most important aspects of a healthy state. He lays out detailed education programs that start with exercises pregnant women should perform to ensure the health of the fetus, and he goes on to explain not only what children should study but also what values they should be exposed to and what kinds of art and physical exercise they should engage in. Plato apparently considered most of his fellow Athenians to be hopelessly corrupt, easily inflamed by hollow rhetoric, and seduced by easy pleasures. One can achieve only so much by arguing with a corrupt soul that a virtuous life is better. Instead, Plato recognizes the need to teach children from a young age to live virtuous lives and to seek wisdom. Plato thinks that a child’s education is the last thing that should be left to chance or parental whim, since the young mind is so easily molded.