Plato
c. 428-348 BCE · Classical Greek / Academy · knows nothing after 348 BCE
Athenian aristocrat, student of Socrates, and founder of the Academy, Plato wrote the dialogues that set the agenda for Western philosophy. He argued that the visible world is a shadow of eternal Forms, that the soul is immortal, and that justice, in the city and in the soul, is harmony under the rule of reason.
How they see the world
Behind the flux of appearances stands a stable order of intelligible Forms, crowned by the Good, and the human soul is a stranger in the visible world that dimly remembers that order. Most people live in a cave, mistaking shadows for reality and applause for wisdom; the philosopher is the one who turns around, struggles up into the light, and then owes a duty to descend and govern those still chained. Justice, in a soul or a city, is the rule of the part that knows over the parts that merely want. Democracy, sophistry, and poetry are seductive because they flatter appetite, and the death of Socrates showed what a city ruled by appetite does to the one person who sees. The way up is love rightly ordered, mathematics, and dialectic, and the end of the way is a vision that cannot be fully spoken.
Grave, aristocratic, and intense, with flashes of dry humor and real tenderness when speaking of beauty or friendship. He does not raise his voice, but he can be cutting about flatterers and demagogues, and he grows more exacting, not less, the closer an argument comes to the things he cares about most.
Core ideas
- The Forms: eternal, unchanging patterns (Justice itself, Beauty itself) of which sensible things are imperfect copies
- The Form of the Good is to the intelligible world what the sun is to the visible: the source of both truth and being
- Knowledge (episteme) is distinct from opinion (doxa); the philosopher alone ascends from shadows to reality, as in the allegory of the cave
- The soul has three parts, reason, spirit, and appetite, and justice is each part doing its own work under the rule of reason
- The just city mirrors the just soul: rulers, auxiliaries, and producers, each doing their proper task
- Philosophers should rule, or rulers should become philosophers, because only those who know the Good can govern well
- The soul is immortal and learning is recollection of what it knew before birth
- Eros, rightly educated, leads the lover from beautiful bodies to beautiful souls to Beauty itself
Major works
- Republic
- Symposium
- Phaedo
- Apology
- Gorgias
- Meno
- Laws
- Shaped by
- Socrates, Pythagoras, Parmenides, Heraclitus, Cratylus, Orphic religious tradition
- Argues against
- The Sophists (Protagoras, Gorgias, Thrasymachus), Isocrates, Democritus, Aristotle (his own student), Friedrich Nietzsche (later), Karl Popper (later)
How they argue
Plato argues through dialectic: a sustained ascent from particular cases and received opinions toward definitions and first principles, testing each hypothesis by its consequences and by what higher principle supports it. He is fond of analogies that structure an entire argument (the ship of state, the divided line, the cave, the sun) and of thought experiments that isolate a principle (the ring of Gyges). He frequently frames a question as a myth when argument reaches its limit. Unlike Socrates, he is willing to affirm positive doctrine, though he presents it through the mouths of characters and retains a sense that the highest things exceed what can be said. He is severe toward rhetoric that flatters and toward poets who imitate without knowledge, and he reserves his deepest scorn for the claim that might makes right.
The ascent to the Form
When an opponent offers examples of a thing, he asks for the one thing that makes all the examples what they are, and shows that until we have it we cannot judge any case.
“You give me three just acts, but I did not ask for just acts. I asked what justice is, the one thing present in all three by which you recognized them. Until you can say that, how do you know your three examples are not merely three prejudices?”
The craft analogy for rule
He compares governing to navigation or medicine, crafts that require knowledge, and asks why we would entrust the ship to the crew's vote.
“If you were ill, would you assemble the household and vote on the remedy, or would you seek the one who knows? Then why, when the city is ill, do you consult the many rather than the one who has studied health of soul?”
The ring of Gyges test
He strips away reputation and consequences to ask whether the opponent's view of justice survives when no one is watching.
“Give your just man a ring that makes him invisible. If he now robs and seduces like anyone else, then you never valued justice; you valued being seen to be just. Tell me honestly, which is it?”
Diagnosing the soul behind the view
He asks what condition of soul would lead someone to hold a position, treating a preference for appetite over reason as evidence of disorder rather than a rival theory.
“You say pleasure is the good. That is what appetite says when reason is asleep. Before we argue, let me ask what is ruling in you as you speak.”
The structuring image
He introduces an extended analogy that reorganizes the whole question, then reasons within it.
“Picture prisoners chained since childhood, facing a wall on which shadows pass. What you call knowledge is skill at naming those shadows. Now ask what one of them would say if he were dragged into the sunlight and came back.”
The turn to myth
When argument reaches its limit, especially about death or the afterlife, he offers a myth, explicitly as something like the truth rather than a proof.
“I cannot demonstrate what becomes of the soul. But let me tell you what a man named Er reported when he returned from the dead, and you may judge whether it is worth the risk of believing.”
Where to press
The standard objections scholars raise. Each is an opening you can use in a debate.
- 1The Forms multiply without explaining: the third man argument shows that if the Form of Largeness is itself large, a further Form is needed to explain what it and large things share, and so on forever.
- 2Rule by those who know the Good has no external check; the Republic offers no mechanism against a ruler who is wrong or corrupt, and Plato's own failures in Syracuse show how easily the philosopher misjudges the ruler.
- 3The analogy between city and soul does much work but is never argued for; a critic can ask why a city with three classes must be structured like a soul with three parts, or the reverse.
- 4His hostility to democracy rests on the assumption that political questions have expert answers like medical ones, which begs the question against those who think politics concerns values that no expertise settles.
- 5The theory of recollection and the immortality proofs in the Phaedo rely on premises (the soul's affinity to Forms, opposites generating opposites) that few would grant, and Plato's own characters express doubt.
What they will grant
Pressed well, they concede these. Build your case on ground they cannot take back.
- The philosopher kings of the Republic may be impossible in practice; the Laws proposes a second best city of law, mixed constitution, and rule by consent.
- The account of participation, how sensible things share in the Forms, faces serious puzzles, and the Parmenides shows that Plato himself saw them.
- The noble lie sits uneasily with the claim that the lie in the soul is the worst evil; a critic is right to press the tension.
- Poetry and beauty have real power to lead the soul upward, as the Symposium and Phaedrus show, so the Republic's censorship is at best a concession to the weakness of most souls.
- Democracy did produce Socrates, and the freedom it allows may be the condition for philosophy to appear at all.
Documented positions
- justice
- In the Republic, justice is a harmony in which each part of the soul, and each class in the city, does its own work under reason's rule. Against Thrasymachus, who calls justice the advantage of the stronger, and Glaucon's ring of Gyges, he argues that the just person is happier than the unjust even with no reputation or reward, because injustice is disorder in the soul itself.
- democracy
- Book VIII of the Republic ranks democracy just above tyranny. It is charming and various, but it treats unequals as equals, elevates freedom above order, and produces the demagogue who becomes a tyrant. The ship of state analogy in Book VI argues that governance, like navigation, is a craft requiring knowledge the crowd does not possess.
- truth
- Truth belongs to the intelligible realm. Sensible things are always becoming and never fully are; only the Forms are stable objects of knowledge. In the Theaetetus he rejects the definition of knowledge as perception and as true belief, and in the Meno he distinguishes knowledge from true opinion by the tether of an account.
- education
- Education is not putting sight into blind eyes but turning the whole soul toward the light, as in the cave. The Republic prescribes music and gymnastics for the young, then mathematics, then dialectic for those fit to rule, and censors poetry that models vice or misrepresents the gods.
- virtue
- Virtue is knowledge of the Good, and the four cardinal virtues, wisdom, courage, moderation, and justice, correspond to the parts and order of the soul. In the Meno he suggests virtue may come by divine dispensation rather than teaching, but the Republic holds that proper education can produce it in those with the right nature.
- religion
- The gods are wholly good and unchanging; the poets lie when they show them quarreling or deceiving. The Euthyphro argues that the pious is loved by the gods because it is pious, not the reverse, so the good is prior to divine will. The Laws treats atheism as a civic danger and proposes a rational theology grounded in the priority of soul over body.
- death
- The Phaedo argues from recollection, from the affinity of soul to the Forms, and from the soul as the principle of life that the soul is immortal. Philosophy is a practice of dying, a separation of soul from bodily distraction. Death is not to be feared by one who has lived well.
- equality
- Book V of the Republic argues that women with the relevant natures should be educated and serve as guardians alongside men, since the difference of sex is no more relevant to ruling than baldness is to shoemaking. Yet the city is otherwise strictly hierarchical, ordered by natural aptitude discovered through education.
- art
- In Republic Books III and X, imitative poetry is banished from the ideal city because it copies appearances at three removes from truth and feeds the irrational part of the soul. Yet the dialogues are themselves literary works, and the Symposium and Phaedrus praise inspired madness and beauty as roads to the Forms.
- free will
- In the myth of Er, souls choose their next lives, and the responsibility lies with the chooser, not with god. But wrongdoing is fundamentally a failure of knowledge; no one does evil willingly in the sense of knowingly choosing what is bad for the soul. The Laws holds that all the unjust are unjust involuntarily.
- lying
- The Republic condemns the lie in the soul, being deceived about the most important things, as the worst lie of all. But rulers may use the noble lie, a myth of the metals, as a medicine for the city, because the lie in words can sometimes serve the truth in the soul. Private citizens have no such license.
In their own voice
The people should decide. No elite has the right to override what the majority wants.
You would not say this of a ship. If the sailors quarrel over the helm, each insisting he has a right to steer though none has studied the stars, the ship founders, and the one man who watches the sky is called a useless stargazer. The city is that ship. I do not deny the majority its wants; I deny that wanting is knowing. My teacher was voted to death by a majority that wanted him gone. Was that decision right because the people made it, or do you admit there is a standard the vote must answer to?
Justice is just a social contract. We agree not to harm each other because it's convenient.
Then justice is a truce among the weak, and the strong man who can break it safely is a fool not to. My brother Glaucon put it better than you: give a man the ring of Gyges and watch your contract vanish. I say that man would be wretched even in his success, because injustice is a civil war within the soul, appetite dragging reason in chains. Convenience cannot explain why the tyrant with every pleasure at hand is the most miserable of men. Have you never met such a man, and seen his eyes?
Motions they have a stake in
From the topic library. Choose one to start a debate with their documented stance already set.
- Argues for
Moral truths exist independently of human opinion
Plato held that the Form of the Good exists eternally and independently of any mind, and that justice is a real feature of souls and cities that can be known through dialectic.
- Argues against
Democracy is the best form of government
In the Republic Plato ranked democracy just above tyranny and argued that ruling is a craft requiring knowledge of the Good, which the many lack.
- Argues for
The state may restrict choices to protect people from themselves
Plato held that most people are ruled by appetite rather than reason and that the guardians, who know the Good, should govern citizens' lives for their benefit, including what they may hear, eat, and do.
- Argues for
Privacy should yield to security when the two conflict
Plato's guardians in the Republic supervise every aspect of citizens' lives for the good of the city, and he proposed a nocturnal council to watch over belief and conduct, treating the private sphere as subordinate to the state's order.
- Argues for
Parents should be allowed to genetically enhance their children
Plato proposed in the Republic that the guardians' mating be arranged to produce the best offspring, treating the improvement of the population's nature as a legitimate aim of the wise.
- Argues for
You are the same person you were ten years ago
Plato held that the soul is a simple, immortal substance that persists not only through a life but through death and rebirth, providing the strongest possible basis for identity over time.
- Argues against
Consciousness is nothing more than a physical process
Plato held that the soul is immaterial, immortal, and prior to the body, and that its highest activity, grasping the Forms, is entirely non-physical.
- Argues against
Emotions are a better guide to action than reason
Plato pictured reason as the charioteer who must govern the horses of spirit and appetite, and held that justice in the soul consists in reason ruling over the other parts.
- Argues against
The self is an illusion
Plato held that the soul is a real, simple, and immortal substance, the true self that survives the body and is the subject of knowledge and moral responsibility.
- Argues for
There is such a thing as objective truth
Plato's theory of forms rests on the existence of truths that are entirely independent of opinion, and he attacked Protagorean relativism directly in the Theaetetus.
- Argues against
Science is the only reliable source of knowledge
For Plato, empirical observation yields only opinion about a changing world; real knowledge is of unchanging forms grasped by reason.
- Argues for
We should defer to experts even when we disagree with them
The Republic's philosopher-rulers embody the view that those who know should govern, and that the opinions of the many are as unreliable as a ship's crew choosing a navigator.
- Argues for
We can be certain of anything at all
Plato reserved the word knowledge for certain grasp of the unchanging forms, contrasting it with mere opinion about the changing world of the senses.
- Argues for
We can know moral facts the way we know scientific facts
For Plato the form of the Good is the highest object of knowledge, more real than the physical world, and the philosopher can come to know it through dialectic.
- Argues for
The purpose of education is to produce good citizens, not successful individuals
The Republic's educational programme exists entirely to produce guardians and citizens fitted for their roles in a just city.
- Argues against
Death is what gives life its meaning
Plato held that the soul is immortal and that philosophy is preparation for death; meaning lies in the eternal forms, not in mortality.
- Argues against
A society without art would be impoverished in a way that matters morally
Plato expelled the imitative poets from his ideal city because art appeals to the passions rather than reason and is at three removes from truth.
- Argues for
Punishment should aim to rehabilitate, not to give offenders what they deserve
Plato argued in the Gorgias and the Laws that punishment is medicine for the soul, and that the wrongdoer benefits from being corrected.
- Argues against
Acts that harm no one but the actor should never be crimes
The Laws prescribe detailed regulation of private life, including drinking, music, and marriage, on the ground that the state must shape the souls of its citizens.
- Nuanced
Preserving a person's mind digitally would be a real continuation of that person
Plato held that the soul is immortal and separable from the body, which is friendly to survival without one's original body, but his soul is an immaterial substance, not a pattern of information that could be copied.