Home > Positioning > Persons > Plato

Plato (c. 428–348 BCE)

Plato set philosophy’s agenda for two-and-a-half millennia. The theory of Forms — that behind the changing world of appearances there exist unchanging, perfect realities grasped by reason — established the hierarchy that still organises philosophy: the intelligible above the sensible, knowledge above opinion, truth above appearance. The dialogues are literature and philosophy at once, which makes Plato’s banishment of the poets from the ideal city one of the most striking self-contradictions in the history of thought. Alfred North Whitehead called the European philosophical tradition “a series of footnotes to Plato.” The footnotes have been arguing with him ever since.

Life

Born in Athens into an aristocratic family during the Peloponnesian War. The decisive event of his formation was the trial and execution of Socrates in 399 BCE — the city’s condemnation of its most honest citizen. The trauma runs through the dialogues: the question of justice, the hostility between philosophy and democratic politics, the suspicion of rhetoric and persuasion. After Socrates’ death Plato travelled — to Megara, possibly to Egypt, to southern Italy where he encountered Pythagorean mathematics, and three times to Syracuse, where his attempts to educate the tyrant Dionysius II ended in failure and danger. Around 387 BCE he founded the Academy in Athens, the first institution of higher learning in the Western world. It survived for nearly nine centuries.

Plato wrote exclusively in dialogue form. Socrates is the central speaker in most dialogues, but how much is the historical Socrates and how much is Plato using Socrates as a mouthpiece is debated and probably undecidable. The dialogues are conventionally grouped into early (the Socratic dialogues — Euthyphro, Apology, Crito, Meno), middle (the great constructive works — Phaedo, Symposium, Republic, Phaedrus), and late (the self-critical and cosmological works — Parmenides, Theaetetus, Sophist, Timaeus, Laws). The grouping is contested, but the broad development — from Socratic questioning to constructive metaphysics to self-revision — is widely accepted.

The theory of Forms

The central doctrine of the middle dialogues. Behind the world of particular, changing things — particular beds, particular acts of justice, particular beautiful things — there exist Forms (eide, ideai): perfect, unchanging, non-physical realities. The Form of the Bed is what makes all particular beds beds. The Form of Justice is what makes just acts just. The Form of the Good illuminates all the others, as the sun illuminates the visible world.

Particular things participate in or imitate their Forms, but they never fully embody them. Every particular bed falls short of the Form of the Bed; every just act is imperfectly just. The gap between the particular and the Form is permanent. Knowledge is of the Forms; opinion is of the particulars. The philosopher ascends from the world of appearances to the intelligible world of Forms.

The theory establishes a hierarchy that runs through the entire subsequent tradition: the intelligible above the sensible, the universal above the particular, the permanent above the changing, reason above the senses. This hierarchy is what Nietzsche later called “Platonism” and set out to invert: “My philosophy is inverted Platonism: the further something is from true being, the more beautiful, the better it is.”

Plato himself subjected the theory to critique. The Parmenides raises the “third man argument” — if a particular resembles its Form, the resemblance requires a further Form to explain it, generating an infinite regress. Whether the late dialogues abandon, revise, or deepen the theory of Forms is one of the oldest questions in Plato scholarship.

Knowledge and the divided line

The Republic (Books V–VII) presents a hierarchy of cognition mapped onto levels of reality:

Imagination (eikasia) — engagement with images, shadows, reflections. The lowest grade.
Belief (pistis) — engagement with physical objects. Ordinary experience. Still opinion, not knowledge.
Reasoning (dianoia) — engagement with mathematical and abstract objects. Uses hypotheses and proceeds downward to conclusions. Genuine thought, but not yet the highest.
Understanding (noesis) — direct apprehension of the Forms, ascending to the Form of the Good. The highest grade. Dialectic — philosophical argument — is the method.

The cave allegory dramatises the ascent. Prisoners chained facing a wall see only shadows cast by objects behind them. One prisoner is freed, turns to see the objects, then climbs out of the cave into sunlight, eventually able to look at the sun itself (the Good). Returning to the cave, he cannot convince the prisoners that their shadows are not reality.

The educational implication is explicit: philosophy is the turning of the soul from the world of becoming to the world of being. The political implication follows: only those who have made the ascent — the philosophers — are fit to rule.

The Republic — justice and the ideal state

The Republic is Plato’s central work, framed by the question “What is justice?” Socrates argues that justice is the proper ordering of parts — in the soul and in the city.

The soul has three parts: reason, spirit (thumos), and appetite. Justice in the individual is reason ruling, spirit enforcing, appetite obeying. The city has three corresponding classes: philosopher-rulers (reason), guardians (spirit), and producers (appetite). Justice in the city is each class performing its proper function.

The philosopher-king — the philosopher who has ascended to knowledge of the Good and returns to govern — is Plato’s answer to the problem that political power and philosophical wisdom rarely coincide. “Until philosophers rule as kings or those who are now called kings genuinely and adequately philosophise, cities will have no rest from evils.”

The Republic also contains the most extensive treatment of education in antiquity, the theory of Forms (the divided line, the cave), the critique of democracy (the ship-of-state analogy), and the attack on poetry and the arts (Book X).

Aesthetics — mimesis and the banishment of the poets

Plato’s treatment of art is the origin of aesthetics’ subordination within philosophy.

In Republic X, the arts are mimesis — imitation. The painter who paints a bed imitates the carpenter’s bed, which itself imitates the Form of the Bed. Art is thrice removed from truth. Worse, art appeals to the irrational parts of the soul — it stirs emotion, weakens reason, encourages identification with characters who express uncontrolled grief or anger. The poet and painter have power but no access to truth.

The conclusion is the banishment of the poets from the ideal city. Not all poetry — hymns to the gods and praises of good men are permitted — but tragic and epic poetry, the heart of Greek cultural life, is expelled. Plato acknowledges the sacrifice: “We are very conscious of her charms; but we may not on that account betray the truth.”

The Ion complicates the picture. The rhapsode Ion cannot explain why he is able to speak well about Homer but not about other poets. Socrates suggests that poetic inspiration is divine possession, not knowledge — the poet is a conduit, not an expert. This grants art a source (divine) but not a cognitive status (knowledge). The Phaedrus similarly treats poetic madness as one of the divine forms of inspiration alongside prophetic, ritual, and erotic madness — elevated but irrational.

The Symposium offers the most positive treatment: the ascent from love of one beautiful body, to love of beauty in all bodies, to love of beauty in souls, to love of beauty in institutions and knowledge, to the Form of Beauty itself. Beauty functions here as the engine of philosophical ascent — not a distraction from truth but a pathway toward it. The tension between this view and the Republic’s hostility to art is one of the deepest in Plato’s thought.

Ethics — virtue as knowledge

Plato’s ethics rests on the Socratic thesis that virtue is knowledge. No one does wrong willingly; wrongdoing is always the result of ignorance. If you truly know the Good, you will act accordingly. Vice is a failure of understanding, not of will.

The Meno asks whether virtue can be taught. The dialogue introduces recollection (anamnesis): the soul already knows the Forms from before embodiment; learning is remembering. The slave boy who has never studied geometry is led through a proof — evidence that knowledge is already present, waiting to be drawn out.

The Phaedo develops the argument for the soul’s immortality. The soul is akin to the Forms — simple, invisible, unchanging — and so does not perish with the body. The philosopher’s life is a preparation for death: the separation of soul from body, reason from the senses.

The Timaeus — cosmology

The Timaeus is Plato’s cosmological dialogue. A divine craftsman (the Demiurge) fashions the visible cosmos in the image of an eternal model (the Forms), imposing order on pre-existing chaotic matter. The cosmos is a living, ensouled being — the best possible image of the eternal original.

The Timaeus was the most influential Platonic dialogue in the medieval period, where it was read alongside Genesis as an account of creation. Its mathematical cosmology — the elements composed of geometric solids, the world-soul structured by mathematical ratios — made it the bridge between Platonism and Pythagorean mathematics.

Where Plato stops

The hierarchy — intelligible above sensible, reason above the senses, Forms above particulars — is the most consequential philosophical architecture ever constructed. It is also the most contested. Every major departure in Western philosophy has had to reckon with it.

Aristotle, Plato’s own student, rejected the separate existence of Forms: universals are in things, not in a separate realm. Heidegger argued that the entire history of metaphysics is a history of “Platonism” — the privileging of presence, permanence, and the intelligible — and that overcoming it requires thinking being as event and disclosure rather than as permanent structure. Nietzsche saw Platonism as the origin of the devaluation of life: by placing true reality in an unchanging beyond, Plato made the changing, sensory, bodily world a mere copy and lesser realm. Dewey challenged the spectator theory of knowledge — the idea that knowing is looking at unchanging objects — as the deepest Platonic legacy.

The banishment of the poets set the terms for aesthetics’ relationship to philosophy: art as seductive but unreliable, the senses as a distraction from truth, the aesthetic as subordinate to the rational. The hierarchy Plato established has been contested but never fully dislodged.

Key works

All works are dialogues. The conventional grouping (early, middle, late) is widely used but not uncontested.

Apology — Socrates’ defence speech at his trial
Meno — can virtue be taught? Recollection, the slave boy
Phaedo — the soul’s immortality, the theory of Forms, Socrates’ death
Symposium — love, beauty, the ascent to the Form of Beauty
Republic — justice, the ideal state, the divided line, the cave, the banishment of the poets
Phaedrus — rhetoric, love, divine madness, the charioteer
Parmenides — self-criticism of the theory of Forms, the third man argument
Theaetetus — what is knowledge? Perception, true belief, the problem of false belief
Timaeus — cosmology, the Demiurge, the world-soul, mathematical structure
Laws — the second-best city, practical legislation, Plato’s last work