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The most comprehensive statement of Plato's mature philosophical views appears in Πολιτεια (The Republic), an extended treatment of the most fundamental principles for the conduct of human life. Using the character "Socrates" as a fictional spokesman, Plato considers the nature and value of justice and the other virtues as they appear both in the structure of society as a whole and in the personality of an individual human being. This naturally leads to discussions of human nature, the achievement of knowledge, the distinction between appearance and reality, the components of an effective education, and the foundations of morality.
Because it covers so many issues, The Republic can be read in several different ways: as a treatise on political theory and practice, as a pedagogical handbook, or as a defense of ethical conduct, for example. Although we'll take notice of each of these features along the way, our primary focus in what follows will be on the basic metaphysical and epistemological issues, foundational questions about who we are, what is real, and about how we know it. Read in this fashion, the dialogue as a whole invites us to share in Plato's vision of our place within the ultimate structure of reality.
Book I of The Republic appears to be a Socratic dialogue on the nature of justice (Gk. δικαιωσυνη [dikaiôsunê]). As always, the goal of the discussion is to discover the genuine nature of the subject at hand, but the process involves the proposal, criticism, and rejection of several inadequate attempts at defining what justice really is.
The elderly, wealthy Cephalus suggests that justice involves nothing more than telling the truth and repaying one's debts. But Socrates points out that in certain (admittedly unusual) circumstances, following these simple rules without exception could produce disastrous results. (Republic 331c) Returning a borrowed weapon to an insane friend, for example, would be an instance of following the rule but would not seem to be an instance of just action. The presentation of a counter-example of this sort tends to show that the proposed definition of justice is incorrect, since its application does not correspond with our ordinary notion of justice.
In an effort to avoid such difficulties, Polemarchus offers a refinement of the definition by proposing that justice means "giving to each what is owed." The new definition codifies formally our deeply-entrenched practice of seeking always to help our friends and harm our enemies. This evades the earlier counter-example, since the just act of refusing to return the borrowed weapon would clearly benefit one's friend. But Socrates points out that harsh treatment of our enemies is only likely to render them even more unjust than they already are. (Republic 335d) Since, as we saw in the Phaedo, opposites invariably exclude each other, the production of injustice could never be an element within the character of true justice; so this definition, too, must be mistaken.
At this point in the dialogue, Plato introduces Thrasymachus the sophist, another fictionalized portrait of an historical personality. After impatiently dismissing what has gone before, Thrasymachus recommends that we regard justice as the advantage of the stronger; those in positions of power simply use their might to decree what shall be right. This, too, expresses a fairly common (if somewhat pessimistic) view of the facts about social organization.
But of course Socrates has other ideas. For one thing, if the ruling party mistakenly legislates to its own disadvantage, justice will require the rest of us to perform the (apparently) contradictory feat of both doing what they decree and also doing what is best for them. More significantly, Socrates argues that the best ruler must always be someone who knows how to rule, someone who understands ruling as a craft. But since crafts of any sort invariably aim to produce some external goal (Gk. τελος [télos]), good practitioners of each craft always act for the sake of that goal, never in their own interest alone. Thus, good rulers, like good shepherds, must try to do what is best for those who have been entrusted to them, rather than seeking their own welfare. (Republic 342e)
Beaten down by the force of Socratic questioning, Thrasymachus lashes out bitterly and then shifts the focus of the debate completely. If Socrates does happen to be right about the nature of justice, he declares, then it follows that a life devoted to injustice is be more to one's advantage than a life devoted to justice. Surely anyone would prefer to profit by committing an act of injustice against another than to suffer as the victim of an act of injustice committed by someone else. ("Do unto others before they do unto you.") Thus, according to Thrasymachus, injustice is better than justice.
Some preliminary answers come immediately to mind: the personal rewards to be gained from performing a job well are commonly distinct from its intrinsic aims; just people are rightly regarded as superior to unjust people in intelligence and character; every society believes that justice (as conceived in that society) is morally obligatory; and justice is the proper virtue (Gk. αρετη [aretê]) of the human soul. But if Socrates himself might have been satisfied with responses of this sort, Plato the philosophical writer was not. There must be an answer that derives more fundamentally from the nature of reality.
When Thrasymachus falls silent, other characters from the dialogue continue to pursue the central questions: what is justice, how can we achieve it, and what is its value? Not everyone will agree that justice should be defended as worthwhile for its own sake, rather than for the extrinsic advantages that may result from its practice.
It helps to have a concrete example in mind. So Glaucon recounts the story of Gyges, the shepherd who discovered a ring that rendered him invisible and immediately embarked on a life of crime with perfect impunity. The point is to suggest that human beings – given an opportunity to do so without being caught and therefore without suffering any punishment or loss of good reputation – would naturally choose a life of injustice, in order to maximize their own interests.
Adeimantus narrows the discussion even further by pointing out that the personal benefits of having a good reputation are often acquired by anyone who merely appears to act justly, whether or not that person really does so. (Republic 363a) This suggests the possibility of achieving the greatest possible advantage by having it both ways: act unjustly while preserving the outward appearance of being just, instead of acting justly while risking the outward appearance of injustice. In order to demonstrate once and for all that justice really is valuable for its own sake alone, Plato must show that a life of the second sort is superior to a life of the first sort.
Thrasymachus, Glaucon, and Adeimantus have given voice to a fundamental issue at the heart of any effort to improve human conduct by appealing to the principles of moral philosophy. If what I am morally required to do can (in some circumstances) be different from what I would choose do for my own benefit, then why should I be moral? Plato wrote the remainder of The Republic in an attempt to provide an adequate, satisfying answer to this question.
After Book I, the entire dialogue is pervaded by an extended analogy between the justice of individual human beings and the that of an entire society or city-state. Since the crucial elements of justice may be easier to observe on the larger scale (Republic 369a), Plato began with a detailed analysis of the formation, structure, and organization of an ideal state before applying its results to a description of personal life.
Imagining their likely origins in the prehistorical past, Plato argued that societies are invariably formed for a particular purpose. Individual human beings are not self-sufficient; no one working alone can acquire all of the genuine necessities of life. In order to resolve this difficulty, we gather together into communities for the mutual achievement of our common goals. This succeeds because we can work more efficiently if each of us specializes in the practice of a specific craft: I make all of the shoes; you grow all of the vegetables; she does all of the carpentry; etc. Thus, Plato held that separation of functions and specialization of labor are the keys to the establishment of a worthwhile society.
The result of this original impulse is a society composed of many individuals, organized into distinct classes (clothiers, farmers, builders, etc.) according to the value of their role in providing some component part of the common good. But the smooth operation of the whole society will require some additional services that become necessary only because of the creation of the social organization itself – the adjudication of disputes among members and the defense of the city against external attacks, for example. Therefore, carrying the principle of specialization one step further, Plato proposed the establishment of an additional class of citizens, the guardians who are responsible for management of the society itself.
In fact, Plato held that effective social life requires guardians of two distinct sorts: there must be both soldiers whose function is to defend the state against external enemies and to enforce its laws, and rulers who resolve disagreements among citizens and make decisions about public policy. The guardians collectively, then, are those individuals whose special craft is just the task of governance itself.
Training the Guardians
In order to fulfill their proper functions, these people will have to be special human beings indeed. Plato hinted early on that one of their most evident characteristics will be a temperamental inclination toward philosophical thinking. As we've already seen in the Apology and in the Phaedo, it is the philosopher above all others who excels at investigating serious questions about human life and at judging what is true and best. But how are personal qualities of this sort to be fostered and developed in an appropriate number of individual citizens? (Republic 376d)
The answer, Plato believed, was to rely upon the value of a good education. (Remember, he operated his own school at Athens!) We'll have an opportunity to consider his notions about higher education later, but his plan for the elementary education of guardians for the ideal state appears in Book III. Its central concern is an emphasis on achieving the proper balance of many disparate components – physical training and musical performance along with basic intellectual development.
One notable feature of this method of raising children is Plato's demand for strict censorship of literary materials, especially poetry and drama. He argued that early absorption in fictional accounts can dull an person's ability to make accurate judgments regarding matters of fact and that excessive participation in dramatic recitations might encourage some people to emulate the worst behavior of the tragic heroes. (Republic 395c) Worst of all, excessive attention to fictional contexts may lead to a kind of self-deception, in which individuals are ignorant of the truth about their own natures as human beings. (Republic 382b) Thus, on Plato's view, it is vital for a society to exercise strict control over the content of everything that children read, see, or hear. As we will later notice, Aristotle had different ideas.
Training of the sort described here (and later) is intended only for those children who will eventually become the guardians of the state. Their performance at this level of education properly determines both whether they are qualified to do so and, if so, whether each of them deserves to be a ruler or a soldier. A society should design its educational system as a means to distinguish among future citizens whose functions will differ and to provide training appropriate to the abilities of each.
The principle of specialization thus leads to a stratified society. Plato believed that the ideal state comprises members of three distinct classes: rulers, soldiers, and the people. Although he officially maintained that membership in the guardian classes should be based solely upon the possession of appropriate skills, Plato presumed that future guardians will typically be the offspring of those who presently hold similar positions of honor. If citizens express any dissatisfaction with the roles to which they are assigned, he proposed that they be told the "useful falsehood" that human beings (like the metals gold, silver, and bronze) possess different natures that fit each of them to a particular function within the operation of the society as a whole. (Republic 415a)
Notice that this myth (Gk. μυθος [mythos]) cuts both ways. It can certainly be used as a method of social control, by encouraging ordinary people to accept their position at the bottom of the heap, subject to governance by the higher classes. But Plato also held that the myth justifies severe restrictions on the life of the guardians: since they are already gifted with superior natures, they have no need for wealth or other external rewards. In fact, Plato held that guardians should own no private property, should live and eat together at government expense, and should earn no salary greater than necessary to supply their most basic needs. Under this regime, no one will have any venal motive for seeking a position of leadership, and those who are chosen to be guardians will govern solely from a concern to seek the welfare of the state in what is best for all of its citizens.
Having developed a general description of the structure of an ideal society, Plato maintained that the proper functions performed by its disparate classes, working together for the common good, provide a ready account of the need to develop significant social qualities or virtues.
When each of these classes performs its own role appropriately and does not try to take over the function of any other class, Plato held, the entire city as a whole will operate smoothly, exhibiting the harmony that is genuine justice. (Republic 433e)
We can therefore understand all of the cardinal virtues by considering how each is embodied in the organization of an ideal city.
Rulers Wise Decisions
Soldiers Courageous Actions
Farmers, Merchants, and other People (Moderated Desires)
Justice itself is not the exclusive responsibility of any one class of citizens, but emerges from the harmonious interrelationship of each component of the society with every other. Next we'll see how Plato applied this conception of the virtues to the lives of individual human beings.
Remember that the basic plan of the Republic is to draw a systematic analogy between the operation of society as a whole and the life of any individual human being. So Plato supposed that people exhibit the same features, perform the same functions, and embody the same virtues that city-states do. Applying the analogy in this way presumes that each of us, like the state, is a complex whole made up of several distinct parts, each of which has its own proper role. But Plato argued that there is ample evidence of this in our everyday experience. When faced with choices about what to do, we commonly feel the tug of contrary impulses drawing us in different directions at once, and the most natural explanation for this phenomenon is to distinguish between distinct elements of our selves. (Republic 436b)
Thus, the analogy holds. In addition to the physical body, which corresponds to the land, buildings, and other material resources of a city, Plato held that every human being includes three souls (Gk. ψυχη [psychê]) that correspond to the three classes of citizen within the state, each of them contributing in its own way to the successful operation of the whole person.
In the Phaedrus, Plato presented this theory even more graphically, comparing the rational soul to a charioteer whose vehicle is drawn by two horses, one powerful but unruly (desire) and the other disciplined and obedient (will).
On Plato's view, then, a human being is properly said to be just when the three souls perform their proper functions in harmony with each other, working in consonance for the good of the person as a whole.
Rational Soul (Thinking): Wisdom
Spirited Soul (Willing): Courage
Appetitive Soul (Feeling): Moderation
As in a well-organized state, the justice of an individual human being emerges only from the interrelationship among its separate components. (Republic 443d)
Plato's account of a tripartite division within the self has exerted an enormous influence on the philosophy of human nature in the Western tradition. Although few philosophers whole-heartedly adopt his hypostasization of three distinct souls, nearly everyone acknowledges some differentiation among the functions of thinking, willing, and feeling. (Even in The Wizard of Oz, Dorothy's quest depends upon the cooperation of her three friends – Scarecrow, Lion, and Tin Woodsman – each of whom exemplifies one of the three aspects of human nature.) Perhaps any adequate view of human life requires some explanation or account (Gk. λογος [logos]) of how we incorporate intellect, volition, and desire in the whole of our existence.
In the context of his larger argument, Plato's theory of human nature provides the foundation for another answer to the question of why justice is better than injustice. On the view developed here, true justice is a kind of good health, attainable only through the harmonious cooperative effort of the three souls. In an unjust person, on the other hand, the disparate parts are in perpetual turmoil, merely coexisting with each other in an unhealthy, poorly-functioning, dis-integrated personality. Plato developed this theme in greater detail in the final books of The Republic.