Returning from a religious festival, Socrates encounters Polemarchus and goes with him to the house of his father, Cephalus. The three men begin discussing justice. Both Cephalus and Polemarchus give traditional accounts of what justice is; Socrates shows both to be incomplete. Thrasymachus enters the debate, answering that the very conception of justice is a sham meant to keep the strong at bay. True justice, he contends, is the advantage of the stronger. Socrates tries to rebut Thrasymachus’s claim, but Thrasymachus remains unconvinced.

Glaucon and Adeimantus urge Socrates to prove that justice is good in itself and not only for its consequences. People act justly mostly out of fear of punishment, so if justice is not good in itself, and if they thought they could get away with it, people would have no reason not to act unjustly. Rather than answer their question directly, Socrates proposes to sketch out an ideal republic so that they can determine what role justice plays in this republic.

Socrates proposes a principle of specialization, with each citizen having a particular role to play. A city needs producers for food and shelter, as well as a class of guardians who protect the state’s interests. These guardians are raised according to a rigorous program of education that emphasizes physical fitness, honor, and wisdom. They are shielded from bad influences, such as myths that portray the gods as possessing vices, so that they don’t become too rough or too soft. The best among the guardians are selected as rulers while the others become “auxiliaries,” who act as soldiers. To maintain this strict class structure of workers, auxiliaries, and guardians, Socrates works out a state-sanctioned mythology that discourages people from aspiring to a different class. Class mobility is only possible when a youth in one class is identified with abilities that clearly suit him for a different class.

Socrates identifies three primary virtues in the different aspects of this republic: the guardians possess wisdom, the auxiliaries possess courage, and the workers possess moderation. Justice in the ideal republic does not reside in any particular part of the republic but rather in the structure of the republic as a whole.

Like the just city, the soul of a just person is divided into three parts, with the soul’s justice residing in the proper structuring and balancing of these parts. The soul has an appetitive part that desires money and other earthly goods, such as the producers; a spirited part that desires honor, such as the auxiliaries; and a rational part that desires truth, such as the guardians. The rational part rules in a just soul, ensuring the health of the whole.

The guardian class lives austerely, having no money or material possessions. They live communally, choose sexual partners by lot, and are separated from their children at birth so as to prevent family ties from overriding loyalty to the state. Revolutionary for his time, Socrates sees no reason why women should not have status equal to men.

The guardians are philosopher-kings, not to be confused with his contemporary philosophers. They are more commonly called “lovers of sights and sounds.” These lovers of sights and sounds are drawn only to the appearance of things, whereas true philosophers have knowledge of the unchanging, eternal Forms that lie behind appearance. The world of sights and sounds consists of objects that are not unchanging — for example, a beautiful woman is both beautiful and, in comparison to a goddess, not beautiful. Therefore, the things we see and hear are objects of opinion or belief; maybe they’re beautiful, maybe not. The world of Forms, such as the Form of Beauty, however, has being in an absolute sense, and these Forms are the objects of knowledge.

The highest knowledge to which the philosopher-kings aspire is knowledge of the Form of the Good. Socrates cannot describe directly what this is but rather explains it by offering three analogies: the sun, the line, and the cave. Socrates invites us to imagine prisoners chained to a bench in a cave. All they can see are the shadows moving on the wall in front of then, cast by statues being moved above and behind where the prisoners cannot see. Not knowing any better, these prisoners think of the shadows as real, unable to recognize a higher reality. If the prisoners were released, they could turn around and see that the shadows they thought were real were only projections of the statues behind them. They would then think of these statues as real, like a person who thinks the world of sights and sounds is the most real thing there is. The prisoners might then wander out of the cave and into the outside world. At first, they would be blinded by the light, but they would eventually come to see all the objects of the world around them. They would think of these objects as real, like a person who can grasp by means of thought the Forms that underlie everyday existence. Finally, these prisoners might be able to look at the sun itself and recognize it as the source of all light and all life. The sun is like the Form of the Good: just as the sun is the source of everything in the visible world, the Form of the Good is the source of everything in the intelligible world.

Socrates invites his friends to imagine a line divided first in two and then in two again. The lower part represents the visible world and the upper part represents the intelligible world. The visible world is divided into imagination and belief, belief being better than imagination just as seeing the statues is better than seeing the shadows. The intelligible world is divided into thought and understanding, where thought hypothesizes the existence of Forms based on the visible world and understanding grasps the Form of the Good as a first principle from which everything else follows.

The education of the philosopher-kings is like the progress of a prisoner from out of the cave. In youth, they study mathematics to give them an intimation of an abstract world behind the visible. After rigorous physical training, they study philosophy and then dialectics. At thirty-five, they spend the next fifteen years running affairs of state before finally achieving the rank of philosopher-king at fifty. These philosopher-kings are like the prisoners who can see the sun, and contemplation of the Form of the Good will be their highest aim. However, they must also take care of the republic and train the next generation, just as freed prisoners must return to the cave to help their comrades.

We must recall that at least one purpose of the Republic is to provoke intense thought and discussion, so if we find passages shocking, we can assume this is what Plato would have wanted. As far as justice, Plato finds the just city as the city in which there is the best arrangement, where each citizen is doing what he is supposed to do; "minding his own business," in a sense, and not transgressing against his neighbors. The just city is the city in which the wisest citizen(s) is (are) in charge. The wisest citizens are those who understand justice: how both the city and each citizen ought to be arranged, put together, with reason at the helm and zeal and desires subordinated to, and guided by, reason. Justice for the person means correct arrangement of the parts of a person's soul: harmony, proportion, symmetry. Just as beauty means proportion or symmetry in physical appearance, so justice means proportion or symmetry in the human soul with beauty of the soul equaling virtue. In the just soul, as in the just city, everything is where it should be, including the ruler. The just soul, like the just city, is an organized whole, it has integrity, and is governed by reason. Like notes in a symphony, the parts of a just soul or a just city work together harmoniously.

I may be easily persuaded, but I find Plato's argument rather compelling. I believe upon initial inquiry, I would offer explanations of justice similar to those put forward by Cephalus and Polemarchus, which Plato readily shows are incomplete. His choice to find justice on a clean slate does seem extreme in some sense; I find Aristotle's attempt to fix current society, rather than wipe everything and start over, a more practical response to the question posed. Plato's ideals of equality are appealing though, with men and women held to similar standards, and each class as important as the next. Perhaps the structure is more rigid than one might enjoy today, but Plato had clear objectives in his method. His state sanctioned mythology and censored education also seem at odds with freedoms we experience today, but when viewed in the totality of his constructed republic, they do fit toward his ends. Communal life and separation of children from parents may be the the most shocking aspect put forward, at least in my view, and I struggled to understand the exact end this means attempt. I do see what Plato was suggesting though, and must admit the concept fits into his bigger plan.

Justice is without doubt the supreme goal throughout this construction, and when viewed as such, and not from the selfish view most everyone naturally takes, the choices made seem to hold firm. I question why no society has indeed tried to implement the structure Plato purposes. Perhaps it is because he is expecting too much from us. Aristotle took existing polities and observed how citizens actually behaved within them while Plato has started completely anew and is projecting the actions of his citizens. The charge remaining then may be to lay out arguments why not to attempt an implementation, for only then can we be sure of how the citizenry will behave. The republic constructed is a utopian one, and hence never likely to occur naturally, but the justice found in it seems to be universal to all of the citizens there doing what they are supposed to be doing. I can imagine that given the specialized education and other safeguards proposed, the system would operate much like the mechanical workings of any great machine.

As we all know, though, regardless of how well a machine is engineered and then built, it does not operate indefinitely. Parts wear and eventually break, as I must suppose the citizens of even this ideal republic would. I see justice as the finest lubricant between the gears of a great engine, and year after year the wheel of perfect harmony turns, emitting a beam of light to all those which observe. Inevitably the lubrication fails, the parts wear, and this great engine ceases. There is opportunity to renew the oil and refill other fluids, but after some unknowable time the engine, the republic, will fail and require rebuilding.

This is not unlike any other thing ever though, and should not be counted too heavily against Plato's state. I believe his choice of justice as the lubricant stands strong, and his structuring of his republic around it a worthy effort. It may be more of an issue of the component parts, no matter how well constructed, that will eventually tire, breakdown, and desire change. Broken families, wonder in education, vice in office, these cannot be controlled irregardless, and if that is what Plato's justice is protected by, it seems to me that he might not have been as directly on target as I first supposed.