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Starvard University · Plato's Republic
One long evening of talk in an Athens port town becomes the most argued about book in Western philosophy. Socrates and his friends ask what justice is, build a whole city to find out, and along the way give us a magic ring, a cave full of prisoners, and a vision of the soul that readers are still testing 2,400 years later.
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Here it is, explained like you are 10:
Plato writes a play where the teacher Socrates argues with his friends about one big question: what is justice, and is it better to be good or just to look good? They invent a city, a ring that makes you invisible, and a cave where prisoners watch shadows on a wall. Almost every philosophy class since has started with their argument.
Plato wrote the Republic in Athens in about 375 BC, as a conversation led by his teacher Socrates, who wrote nothing himself. The book has ten parts, called books, and this course follows its great scenes in order: the opening debate, the ring of Gyges, the city built in words, the philosopher king, the cave, the three part soul, and the closing myth of Er. We read it in the translation by Benjamin Jowett, the Oxford scholar whose English version, first published in 1871, is still the one most readers meet first.
We also keep the hard parts in plain view. Plato really does propose censoring poetry, telling citizens a useful lie, ending private families for his rulers, and rule by philosophers with no elections. Lesson by lesson we say where readers, then and now, have objected, and why the cave, the ring, and the picture of the soul still repay the argument.
The whole course in brief
What you will be able to do after this course
The eight lessons
Lesson 1
The book opens mid stride, with Socrates himself telling the story. “I went down yesterday to the Piraeus with Glaucon the son of Ariston”, he begins, at a festival in Athens’ port town. The company gathers at the house of Cephalus, a wealthy, elderly maker of shields, fresh from sacrificing and still wearing his garland. Talk turns, gently, to old age, then to money, and then Cephalus offers the evening’s first definition: justice is speaking the truth and paying what you owe.
It sounds solid, and Socrates breaks it with one gentle case. If a friend lends you his weapons while he is sane and asks for them back after he has gone mad, handing them over would be paying what you owe, and it would plainly be wrong. The definition falls. Cephalus smiles, hands the argument to his son Polemarchus, and goes back to his sacrifices. Polemarchus reaches for the poet Simonides: justice is giving every man his due, helping friends and harming enemies. Socrates presses again. A man can also mistake who his friends are, and harming anyone makes that person worse, a strange job for justice.
Then Thrasymachus, a famous professional teacher of rhetoric who has been straining to get in, bursts into the room with the bluntest answer of the night: “I proclaim that justice is nothing else than the interest of the stronger”. Rulers, he says, make laws to suit themselves and call obedience to those laws justice. Socrates answers with crafts. A shepherd, a doctor, a pilot, considered strictly as craftsmen, aim at the good of what they tend, not their own. Book I ends with Socrates admitting he still does not know what justice is. But the table has been set perfectly for the real argument.
Lesson 2
Glaucon, Plato’s brother, is not satisfied, and he says so. Socrates has beaten Thrasymachus, but he has not proved the thing that matters. Glaucon sorts goods into three kinds. Some we welcome for their own sake alone, like harmless pleasures. Some we value both for themselves and for what they bring, like health and good sense. Some are burdensome but pay off, like medicine and exercise. Most people, Glaucon says, file justice under the third kind: worth the trouble only because of wages, honour, and reputation. He demands that Socrates move it, with proof, into the second class, and show what justice itself does to the soul of the person who has it, even if gods and men never notice.
To sharpen the demand, Glaucon tells a story. “Gyges was a shepherd in the service of the king of Lydia”, he begins. After an earthquake split the earth open, Gyges climbed down into the crack and found a hollow bronze horse, and inside it a giant corpse wearing a gold ring. He took the ring, and later, idly turning its bezel inward at a shepherds’ meeting, he vanished. Turned outward, he reappeared. He understood his luck, got himself sent to court as a messenger, seduced the queen, murdered the king with her help, and took the throne.
Now run the experiment fairly, Glaucon says. Give two rings, one to a just man and one to an unjust man, and watch both. Nobody, he claims, would keep his hands off other people’s goods, houses, and lives if he could act with total impunity, which suggests that people are just only under compulsion, out of fear. Then strip reputation away entirely. Imagine the perfectly just man believed by everyone to be a criminal, scourged and tortured and finally killed, while the perfectly unjust man enjoys a spotless reputation and every reward. Which life is happier? Socrates accepts the challenge at full strength. It will take him nine more books to answer.
Lesson 3
Socrates proposes a change of scale. Justice in one small soul is like small print, hard to read. So let us read it in large letters first, in a city, and then carry what we find back to the individual. The company agrees to build a city in words. A city begins, Socrates says, because none of us is self sufficient. We need food, shelter, and clothing, and we get them best by dividing the work: “all things are produced more plentifully and easily and of a better quality when one man does one thing which is natural to him”. So the first city fills up with farmers, builders, weavers, shoemakers, and merchants, living simply and growing old in peace.
Glaucon interrupts: that is a city fit for pigs. Where are the couches, the relishes, the perfumes, the art? Socrates concedes the point and calls the simple city the healthy one, and the luxurious city a city with a fever. Luxury changes everything. More land is needed, and land must be taken from neighbours, which is where war comes from. War needs specialists, so a new class appears: the guardians, soldiers by nature and training, who must be fierce toward enemies and gentle toward their own people. Socrates finds that combination in a well bred dog, loving to everyone it knows and hostile only to strangers.
To hold this growing city together, Socrates proposes something this course will not soften: a founding story he openly calls a lie, the famous noble lie, meant if possible to persuade even the rulers themselves. Citizens are to be told they were formed inside the earth, all brothers, but with different metals mixed into their souls by the god: gold in the rulers, silver in the auxiliaries, iron and bronze in the farmers and craftsmen. A child showing the wrong metal must be moved, up or down, to the class that fits. Readers have objected to it from the start: it is propaganda. Plato’s defence is visible in the design. The myth makes every citizen kin, and it ranks people by nature rather than by birth, since golden parents can have an iron child who must be demoted. Whether that redeems a state built partly on a useful fiction is a question the book leaves you holding.
Lesson 4
Guardians are made, not born, and their making starts before any lessons in virtue could possibly be argued for. “Shall we begin education with music, and go on to gymnastic afterwards?” Socrates asks. Music here, the Greek mousike, covers stories, song, and melody, with gymnastic training for the body alongside. Children absorb tales long before they can reason about them. So the regime begins with control of storytelling: “Then the first thing will be to establish a censorship of the writers of fiction”, letting approved tales through and rejecting the rest.
What gets rejected is specific, and it includes Greece’s most beloved books. Homer and Hesiod, Socrates argues, tell stories of gods who lie, cheat, fight their families, and laugh at suffering. A child cannot sort symbol from example, and will conclude that divine behaviour excuses his own. In the permitted stories, gods must be good and truthful, and heroes must not fear death. The censorship does not stop at childhood reading. By the final book of the Republic, poetry itself, the great imitative art of Athens, is largely banished from the city, with an exception for hymns to the gods and praises of famous men. This is really in the text, and it is the proposal modern readers most often choke on: the philosopher who wrote the most beautiful dialogues in Greek planned a city with very little poetry in it.
His reasons are worth hearing before the verdict. Rhythm and harmony, Socrates says, sink further into the soul than anything else, taking hold of it and shaping its grace or clumsiness before reason ever arrives. Gymnastic, kept simple, builds guardians who are awake and hardy. Too much music alone makes a man soft. Too much gymnastic alone makes him savage. The educated guardian holds both in tune, like the strings of one instrument. The honest worry stands beside the design. A regime that forms character this thoroughly, by choosing every story a child hears, buys its harmony at a real price in freedom, and Plato knew the price and paid it on purpose.
Lesson 5
Everything so far has been preparation for the proposal Socrates says he is afraid to utter, the greatest of three waves of ridicule he expects to drown in. He says it anyway: “Until philosophers are kings, or the kings and princes of this world have the spirit and power of philosophy”, cities will have no rest from their evils. The first wave was that guardian women should be educated and serve on equal terms with men. The second wave is harder. The third, rule by genuine philosophers, is the one the whole city exists to make possible.
The second wave concerns the family, and again this course keeps it unsoftened. Socrates lays down “that the wives of our guardians are to be common, and their children are to be common, and no parent is to know his own child, nor any child his parent”. Guardian children are raised in a common nursery. Marriages are temporary, arranged at festivals, with the lots quietly rigged by the rulers so that the best guardians mate most often. Private households, private property, and private grief and joy are abolished for the ruling class, so that no guardian can ever say mine about a child, a house, or a purse, and so pull the city apart. Plato sees the gain clearly: the guardians become one family, feeling one another’s pains as their own.
Who, then, is this philosopher fit to rule? Not a lover of opinions or of pretty sights and sounds, but someone who loves truth whole and pursues knowledge of what things really are, the unchanging patterns Plato calls Forms, of which everyday things are copies. They are tested, educated for years, and rule reluctantly, as a duty, not a prize. There are no elections anywhere in this design. Rulers are selected and trained, never chosen by the citizens they govern. Karl Popper, in The Open Society and Its Enemies, famously read the Republic as a blueprint for a closed and authoritarian society, and readers have been arguing with Popper, and with Plato, ever since. The question survives: knowledge should matter in ruling, and consent matters too, and nobody has made the two sit easily together.
Lesson 6
At the start of Book VII, Socrates offers the book’s most famous picture, an image, he says, of our nature in its enlightened and unenlightened state: “Behold! human beings living in a underground den, which has a mouth open towards the light”. The prisoners have been chained since childhood by the legs and neck, facing a wall. Behind them burns a fire, and along a raised path in front of the fire, carriers pass holding statues and figures of animals and objects, whose shadows the fire throws onto the wall. The prisoners name the shadows and honour whoever predicts them best. “To them, I said, the truth would be literally nothing but the shadows of the images”.
Now free one prisoner, Socrates says, and make him stand, turn, and climb. Every step hurts, and dragged up the steep rough ascent into daylight, he is at first blinded completely. Sight returns in stages: shadows, reflections, the things themselves, the moon and stars, and last of all the sun itself, source of the seasons and of sight. In the argument, the cave is the world we see, and the sun is the Form of the Good, seen last and with great effort, the cause of everything right and beautiful.
The ending is not cheerful, and it is aimed at Athens. Send the freed prisoner back down, Socrates says, and in the darkness he will fumble at the shadow contests and look ridiculous, while his eyes adjust. The prisoners will say the journey up ruined his sight, and if someone tries to free another of them and lead him up, they will catch the liberator, if they can, and put him to death. Every first reader knew who that described: Socrates himself, executed by Athens in 399 BC. Education, the picture teaches, is not putting sight into blind eyes. It is the art of turning the whole soul around, slowly and painfully, toward the light, and the philosopher who has made the climb owes the cave a return trip, to rule and teach in the dark he escaped from.
Lesson 7
Strictly, this division comes earlier in the book than the cave, in Book IV, where Socrates goes hunting for justice inside the individual. His tool is a plain observation: the same thing cannot do or suffer opposites in the same part of itself at the same time. Yet a thirsty man can want to drink and, in the very same moment, refuse to drink, because some calculation tells him the drink is bad. One part of him reaches, another holds back, so the soul cannot be one simple thing. The part that calculates and restrains is reason. The part that thirsts, hungers, and lusts is appetite.
The third part appears in a story Socrates tells about a man named Leontius, who was walking past the place of execution outside Athens and saw corpses lying on the ground. He longed to look, was disgusted with himself for longing, and finally ran up to the bodies crying out to his eyes to take their fill of the fine sight. That self directed anger is spirit: the part that feels shame, indignation, honour, and competitive fire. In Plato’s phrase, spirit is the part which, “when not corrupted by bad education is the natural auxiliary of reason”.
Now the city and the soul snap together like the two halves of a broken coin. Producers answer to appetite, auxiliaries to spirit, guardians to reason, and the virtues are the same in both. A soul is wise when reason knows what benefits the whole, brave when spirit holds firm, moderate when all three agree about who should rule, and just when each part does its own work and does not meddle in the work of the others. Justice, on this picture, is health of the soul: an inner order you can feel, as different from inner civil war as health is from sickness. That is Glaucon’s answer, delivered at last. The just man is not good because goodness pays. His soul is in tune, with reason governing, spirit loyal, and appetite provided for but seated, and the unjust soul is a tyranny of cravings no success can quiet. Readers still use this map every time they say one part of me wanted it and another part knew better.
Lesson 8
The argument is finished, and Plato closes not with a proof but with a story, after one last claim about the soul itself: “Are you not aware, I said, that the soul of man is immortal and imperishable?” Book X argues that a thing is destroyed by its own special evil, and injustice, the soul’s evil, corrupts but never quite kills it, so the soul endures. Then Socrates tells a tale. “Er the son of Armenius, a Pamphylian by birth. He was slain in battle”, and ten days later his body, alone among the dead, was found uncorrupted. On his funeral pyre he revived, and told what his soul had witnessed.
Er describes a meadow where judges sit between openings in the earth and the sky. The just ascend to the right, wearing their judgments in front of them, to a thousand years of reward. The unjust descend to the left, judgments fastened on their backs, to pay tenfold for every wrong. After seven days in the meadow, the souls travel to a shaft of light binding heaven and earth, where the spindle of Necessity turns. There, lots are cast, and the souls must choose their next lives from a great spread of patterns laid out on the ground: lives of tyrants and private citizens, athletes and animals, mixed with wealth and poverty, health and sickness.
The choosing is the point of the whole myth, and Plato stages it as a warning. The very first soul to choose, a man who had lived virtuously in a well ordered city but by habit rather than by philosophy, snatches the greatest tyranny on offer without examining it, and only afterwards sees that the life includes eating his own children. Odysseus, cured of ambition, gladly takes the pattern everyone passed over: the life of a quiet private man. Socrates draws the moral explicitly: this is the supreme peril of our state, and the one study that matters is learning to discern good lives from bad, so as to “choose always and everywhere the better life as he has opportunity”. The responsibility, the herald proclaims, lies with the chooser; the god is blameless. A course that began with a definition ends with a choice, and Plato hands the choice to you.
Sources
This course is taught from one book, free for anyone to read in full at Project Gutenberg. The Republic was written by Plato in about 375 BC, and Benjamin Jowett's translation of 1871 is the version quoted throughout these lessons.
Graduation
You sat through the whole evening in the Piraeus: the definitions that broke, the ring that made a shepherd a king, the city built in words with its common nurseries and its useful lie, the prisoners blinking in the cave, the soul in its three parts, and Er choosing his next life with care. You also heard the objections honestly, from the censorship to Popper, and you know which parts of this book the world has kept and which it has refused. Congratulations: you can now open any philosophy syllabus in the world and recognise its first ancestor.
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