According to Plato, political theory is married with moral theory. In his masterwork, the Republic, Socrates searches for the nature and value of justice. The dialogue progresses by following an analogy between the soul of individual men and the constitution of the State. Indeed, Plato held that the State is like a giant person. As justice is the general virtue of the moral person, so also it is justice that characterizes the good society. “We should begin,” he says, “by inquiring what justice means in a state. Then we can go on to look for its counterpart on a smaller scale in the individual.”

As souls are best when reason governs appetite and spirit, so those states function best where the ruling class governs the soldiers and guards of the State (the spirited class) and the farmer and artisan class (appetites). If such a state functions with this kind of order, it follows the “order” of a well-functioning soul. Plato concluded that this is what we mean by a just state.

Justice Large and Small

So a consideration of justice in the political realm is inseparable from justice in the individual soul. In ethics Plato follows Socrates, taking many of the same positions. For one, Socrates had argued against the Sophists, who maintained that the good life is pleasure. Plato agreed with his teacher's idea that “Knowledge is virtue.” In fact, he agreed with Socrates' view of morality in general, accepting Socrates' concept of the soul and the concept of virtue as function.

Plato saw a close parallel between the art of music and the art of living. In both cases the art consists of recognizing and obeying the requirements of limit and measure. A musician can only tune his instrument so far and get the right sounds from it. So, too, a sculptor must know how much stone to chisel, else he too will fall short of good art.

So the soul must operate within the limits set by intelligent living. The soul has appetite, spirit, and reason.

The appetites ought to be kept within limits, avoiding excess so as not to usurp the authority of the other parts of the soul. If a person can moderate his love of pleasure and his desires, then he is temperate and possesses the virtue of temperance. If he drinks too much or does drugs to excess or engages in sexual activity without restraint, then, Plato says, he is “like a leaky sieve.” For just like a person trying to hold water in a vessel with holes in it that water runs through, a person seeking pleasures without control can never get his fill. He is intemperate, or lacking in self-control.

Then there is the spirited part of the soul, which is a person's energy of will, but this too must be kept within limits. If such a person is rash, he runs without looking, speaks aggressively without knowing the situation, or acts excessively in some other manner. He has spirit, but his spirit is disconnected to the requirements of the situation. There are people in battle who run recklessly toward the enemy and there are countries that do the same thing. But the person who runs out of his foxhole during infantry battle increases his chances of being shot. His foxhole is for his protection; it increases his chances of survival. If the foxhole is used properly, a soldier can shoot out of it and expose only his helmet, thereby decreasing the chances that the enemy can strike him. But if he acts with just the right amount of spirit, with the right measure, then he is brave.

The virtues are interconnected. Temperance is the rational control of the appetites, and courage is the rational ordering of the spirit. So reason comes into play, reigning over all of them. Only when each part of the soul fulfills its own function is a fourth virtue, justice, attained. Justice is the general virtue. It reflects a person's well-being and inner harmony, which is achieved only when every part of the soul is fulfilling its proper function.

The Philosopher-King and the Decline of the Idea State

Plato has said that a state governed by reason — a state with justice — is an ideal state.

Individuals and states with out-of-control drives and appetites end in strife, that is, internal anarchy. For harmony to prevail, the rational element must be in control. Who should be the captain of the ship? Should it be the most popular person, or the one who knows the art of navigation? Come to that, who should be a shoemaker or a shipbuilder or a flute player? Isn't the expert the one who is a master in each of these functions? Likewise, who should rule the State?

For Plato there is just one answer: the philosopher-king is the one whose education has led him up step by step through the ascending degrees of knowledge of the Divided Line until at last he possesses knowledge of the Good, that synoptic vision of the interrelation of all truths to one another. To reach this point the philosopher-king requires the right education — mostly in mathematics, metaphysics, and dialectic — right up to the time when he has the vision of the Good and is then ready for the task of governing the State.

States not governed by their most reasonable element will suffer declines. Plato argued that if “there are five forms of government, there must be five kinds of mental constitution among individuals.” The five forms of government are aristocracy, timocracy, plutocracy, democracy, and despotism.

Plato considered the transition from aristocracy to despotism (or rule by a tyrant who wields power oppressively) as a step-by-step decline in the quality of the State corresponding to a gradual deterioration of the moral character of the rulers and the citizens. His ideal state was an aristocracy, since here the rational element embodied in the philosopher-king was supreme and people's reason controlled their appetites. Plato was disenchanted with all governments, especially Athenian democracy because of how it had treated Socrates. “I saw clearly with regard to all states now existing that without exception their system of government is bad.” Still, the norm for a state is aristocracy (or rule by a hereditary or noble class; aristos = best, + kratos = rule).

Less desirable is a timocracy. Plato describes this as a state governed on principles of honor and military glory. Timocracy would result from the first stage of decline from an aristocracy. Timocracy represents a love of honor. The problem is that some ambitious members of a ruling class will be insatiably self-seeking and love their own honor more than the common good. In Platonic terms, the spirited parts of their souls will have usurped (over-powered) the role of reason. Timocracy begins a process whereby the irrational part assumes a progressively larger role. It is a short step from love of honor to the desire for wealth, which means allowing the appetites to rule.

Under a timocracy there would be the beginning of a system of private property, and this desire for riches paves the way for a system of government called plutocracy (or government by the wealthy plutos = wealth + kratos = rule), where power resides in the hands of people whose main concern is wealth. And Plato says, “As the rich rise in social esteem, the virtuous sink.” Plutocracy is problematic, primarily because it breaks the unity of the State into two contending classes, the rich and poor. Also, the plutocrat is like the person who seeks constant pleasure. But pleasure is momentary and must therefore be repeated. There can never be a time of perfect satisfaction; the seeker of pleasure can never be satisfied once and for all, any more than a leaky pail can be filled. Still, the plutocrat is torn between many desires because he knows how to distinguish three sorts of appetites: (1) the necessary, (2) the unnecessary, and (3) the lawless. “His better desires will usually keep the upper hand over the worse,” and so the plutocrat, Plato says, “presents a more decent appearance than many.”

Democracy is a further degeneration still, Plato said, for its principles of equality and freedom reflect the degenerate human characters whose whole range of appetites are all pursued with equal freedom. To be sure, Plato's concept of democracy, and his criticism of it, was based upon his firsthand experience with the special form of participatory democracy in the small city-state of Athens. Here democracy was direct in that all citizens had the right to participate in the government once past the age of eighteen. But this direct popular government violated his notion that the rule of a state should be in the hands of those experts with the special talent and training for it.

Democracy is rule “by the many,” Socrates argues in the Apology. The problem is that experts, in technical matters and in moral and political matters, are not the many but the few. It is the many who put Socrates to death, so how wise can a democracy be?

Democracy emerged from plutocracy. It started with the sons of the more restrained father-plutocrats, where the goal of life was to become as rich as possible. “This insatiable craving could bring about the transition to democracy,” said Plato, for “a society cannot hold wealth in honor and at the same time establish self-control in its citizens.” It is when the rich and poor find themselves in a contest under plutocracy that the turning point is reached, for “when the poor win, the result is a democracy.” Thus, “liberty and free speech are rife everywhere; anyone is allowed to do what he likes.” As a result, Plato concluded, “you are not obliged to be in authority, or to submit to authority if you do not like it.”