The Republic of Plato, perhaps the greatest single treatise written on political philosophy, has strongly influenced Western thought concerning questions of justice, rule, obedience, and the good life. The work is undoubtedly the best general introduction to Plato’s philosophy. It contains not only his ideas on the state and human nature but also his theory of forms, his theory of knowledge, and his views of the role of music and poetry in society. Plato presents a penetrating analysis of each of the important philosophical questions. Socrates and his illustrious student Plato force the reader, by their dialectical technique of question and answer, of definition and exception, to take an active part in the philosophical enterprise.

The work is divided into ten books, or chapters, written as a dialogue with Socrates as the main character. One cannot fail to catch the magnificence of Plato’s literary and philosophical style, for all the available translations contain passages of great force and beauty.


The opening book of the Republic is concerned with the question, “What is justice?” Invited by Polemarchus to the home of his father, Cephalus, Socrates and others (among them Glaucon, Adeimantus, and Thrasymachus) begin, in an easy fashion, the search for an answer. First Cephalus and then his son Polemarchus defend the idea that justice is the restoration of what one has received from another. Socrates asks if this definition would apply in a situation in which weapons borrowed from a friend were demanded by him when quite obviously he was no longer of sound mind. It is a homely example of the type that Socrates loved to give; and as usual, when examined, it raises important considerations. Justice, among other things, involves not only property but also conditions, such as a sound mind, which cannot be merely assumed.

The next definition is that justice is doing good to friends and harm to enemies. However, knowledge is needed in order to be able to judge who one’s friends and enemies are. The definition is then modified: Do good to the just and harm to the unjust. Socrates brings up an objection that is a central feature of many of his discussions of the good life. He argues that doing harm to the unjust makes them worse than they are. He holds that it can never be just to make people worse than they are by doing harm to them.

The most serious discussion of this book, which sets the tone for the remainder of the Republic, occurs next. Thrasymachus, who had been sitting by listening to the argument with ill-concealed distaste, impetuously breaks in and takes it up. He presents a position that has since been stated many times: Because the stronger party makes the laws, justice is that which is to the advantage or interest of the stronger party. Socrates attacks this definition: He points out that people do not always know what their interest is or wherein it lies. When the stronger party errs in judgment, then what? Thrasymachus replies that rulers are not rulers when they err. Note that in admitting this, Thrasymachus has already moved away from his original position and toward that of Socrates, which is that might alone does not make right; might together with some kind of knowledge capable of preventing...

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The State

In book 2, Glaucon and Adeimantus press Socrates to prove that the just life is worth living, and Glaucon illustrates his wish by means of the legend of the ring of Gyges. Gyges, so the story goes, gained possession of a ring that when turned made its wearer invisible. With this advantage, he was able to practice evil with impunity. Socrates is to consider an individual with the advantage of Gyges and contrast him with a person who is his opposite. It is his task to show that the life of the just person, no matter what indignities are suffered, is worth living and that it is preferable to that of Gyges. He is to show that virtue is its own reward no matter what the consequences.

Socrates, with misgivings, takes on the task. He suggests, inasmuch as they are searching for something not easily found, justice, that they turn to a subject that will most readily exhibit it. The state is analogous to the individual, and justice, once found in the state, will apply also to its counterpart, the individual.

He begins his quest by a kind of pseudohistorical analysis of the state. People are not self-sufficient and thus cannot supply themselves with all the necessities of life. However, by pooling their resources, and by having people do what they are best suited to do, they will provide food, shelter, and clothing for themselves. The city that these people create then engages in exporting and importing, sets up markets, and steadily advances from its simple beginnings. From simple needs, the people pass increasingly to luxurious wants. Because the necessities of life are no longer sufficient, the people turn to warfare to accumulate booty. Armies are needed and a new professional is born: the soldier, with appropriate characteristics. The soldiers must be as watchdogs, gentle to their friends and fierce to their enemies. (Note that in discussing the characteristics of the soldiers, a spirited group that forms only a part of the state, and analogously, a spirited part of the individual, Socrates suggests a feature formerly given as a possible definition of justice.) The soldier must know his friends, the citizenry, and his enemies, the barbarians, and be good to the one and harm the other. This may be an aspect of justice, but it is not the complete definition. The state also needs rulers, or guardians, who are to be carefully selected and trained.

Plato holds music and gymnastics to be a significant part of the guardian training. He concludes book 2 and takes up much of book 3 with arguments for censorship of the tales...

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The Three Waves

In book 5, Plato discusses the “three waves” that are needed if the ideal state is to be possible. The rulers are to be selected from those who show the proper aptitude, women as well as men. This is the first wave. The second wave is that communal life must be shared by the ruling class. Marriage and children will be held in common. All within a certain age group are to be designated “parents,” a younger group, “children” and “brothers and sisters,” and so on. Plato argues that family loyalty is an asset that, when practiced on a public scale, will retain its value, whereas the deficits of private family life, such as the factiousness between families, will be eliminated. “Mine” and “not mine” will apply to the same things. The ruler will arrange communal marriages by lot; unknown to the betrothed, however, the lottery will be fraudulently arranged for reasons of eugenics. Another myth or lie is told for the state’s benefit. The third wave, and most difficult to bring about, is that philosophers must be kings, or kings, philosophers. If this can occur, then political power and intellectual wisdom will be combined so that justice may prevail.

In books 6 and 7, Plato presents three analogies to illustrate parts of the three waves. Plato believed that those features that objects of a certain kind have in common, for example, the features common to varied art objects, all beautiful, are all related to a single perfect ideal, or form, which he called “the feature itself,” in this case “beauty itself.” This is an intellectual reality properly “seen” by the rational element of the soul, just as the many instances are perceived by sight or by means of the other senses. The good itself, the highest of all forms, is the proper object of the philosopher’s quest.

In his first analogy, Plato likens the good to the sun. Just as the sun provides light so that people can see physical objects, the good provides “light” so that the soul may perceive intellectual forms.

Plato’s second analogy also emphasizes the distinction between the senses and the rational element of the soul as sources of knowing. Imagine a line whose length has been divided into two unequal parts; furthermore, these parts are then divided in the same proportion as the first division. If the line is labeled AE, the first point of division C and the other two points of the subdivisions B and D, then the proportions shown in the diagram hold. Hence BC =...

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The Decline of the State

In book 8, Plato discusses the decline of the state, which is paralleled by the decline of the individuals who make it up; the state is analogous to the individual. From the rational state, one moves to the spirited one (the guardians), the chief virtue of which is honor. When the spirited element is again dominated by appetites, then wealth is sought and the oligarchy born. From wealth, one goes to the government of the many who, overthrowing the few, proclaim the virtues of the group. Appealing to the mob, the demogogue takes over, and the full decline of the ideal state and its members has occurred.

There is a weird similarity; from love of reason to insatiable lust, the state and the individual have degenerated....

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The best society, according to Plato, is a harmonious one, the result of rational coordination of the populace by carefully selected and trained rulers.

Plato identified three classes of citizens who, if they are to live in harmony, must be satisfied with their position on the social hierarchy. At the bottom are the artisans and laborers, who supply the material needs of the state. Next are the soldiers, who defend the state. At the top are the rulers, the few who are selected at birth to be taught how to organize best the state’s social life.

These three classes of citizens correspond to the three parts of human beings as Plato understood them. The first of these is appetite, the physical needs and...

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The Work

Republic consists of a lengthy discussion of the advantages of choosing justice rather than injustice. In order to persuade his interlocutors, Socrates, the protagonist of Republic, uses every rhetorical device available to him, blending images and arguments into a whole that is worthy of the name “cosmos.” Included in the work are fictional regimes, noble lies, an analogy of the good, allegories exposing human ignorance, geometrical explanations of knowledge, an image of the soul in speech, and a myth. The interlocutors, however, remain skeptical. They see no reason to believe that the soul has conflicting powers that are in need of intelligent governance, and they doubt that a...

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Additional Reading

Brumbaugh, Robert S. Plato for the Modern Age. New York: Crowell-Collier, 1962. A good introduction to Plato’s thought and the Greek world in which he developed it.

Copleston, Frederick. A History of Philosophy: Greece and Rome. Garden City, N.Y.: Doubleday, 1969. Copleston devotes several clear chapters to a discussion of the full range of Plato’s view.

Cropsey, Joseph. Plato’s World: Man’s Place in the Cosmos. Chicago: University of Chicago Press, 1995. Discusses Plato’s views on human nature with attention to his political theories.


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