Plato

The doctrine answers the paradox of the Meno: one can seek neither what one already knows nor what one wholly ignores, having no way to recognize it. Plato concludes that all learning must be a recollection, anamnesis, of Forms the soul contemplated before birth. The proof is experimental, not asserted: questioned by the method of questions alone, the slave boy of the Meno, who never learned geometry, recovers a theorem on his own, which rules out his having received it through the senses. Knowledge therefore comes from within, from reason turned toward the intelligible, against all empiricism.

Seeking and learning are in fact nothing but recollection.Meno, 81d

Meno, 81a-86c · Phaedo, 72e-77a

Against sophistic relativism, Plato holds, especially in the central dialogues, that stable knowledge, epistēmē, is possible: it bears on the Forms and is rigorously distinct from mere opinion, doxa, shifting and groundless. This confidence in a science of being brings him close to dogmatism, even if the interrogative form of the dialogues tempers any systematisation.

Republic, V, 476d-480a · Theaetetus, 187a-201c

The theory of Forms is realism about universals par excellence: the beautiful, the just, the circle exist in themselves, beyond the sensible, and particular things are only imperfect reflections of them. The universal is more real than the individual.

Republic, VI-VII; Phaedo

Leaving the cave is painful, blinding, and yet the only liberation: to stay among the shadows is to take reflections for reality and live in chains without knowing it; knowing is not an ornament of happiness but the conversion of the whole soul toward what is. Yet the philosopher-king administers a noble lie to the city: the primacy of truth holds first for the soul being educated, and Plato accepts that the common order may itself rest on a myth.

Republic, VII · Republic, III

Plato is one of the major sources of essentialism: each sensible thing is what it is only by participating in an intelligible, eternal and immutable Form that constitutes its true essence. The theory of Forms, especially in the Phaedo and the Republic, makes essence a separate being, prior and superior to individual existence.

Phaedo, 74a-75d · Republic, V, 476a-480a

If the soul knows the eternal and unchanging intelligible, it is because it is akin to it: what grasps the simple must itself be simple. From this kinship Plato concludes that the true self is not the bodily composite but the soul, an immaterial substance that preexists birth and survives death. The Alcibiades sharpens the divide: a person is neither the body nor the compound of both, but "is" the soul, the body being merely an instrument it uses. This identification of the person with a separable substance, against any self bound up with embodiment, grounds the whole of Platonic psychology and eschatology.

Phaedo, 78b-80b · Alcibiades, 129e-130c

The Phaedo does not posit survival, it argues for it, through four linked proofs: the generation of opposites, recollection which presupposes knowledge prior to birth, the soul's affinity with the simple and indestructible intelligible, and finally the essence argument, the soul that carries life within it being unable to admit its contrary. The reasoning rests on the dualism of soul and body: what is simple does not decompose, hence does not perish. Death then ceases to be annihilation and becomes the soul's passage toward the intelligible, and philosophy itself, as detachment from the body, is its anticipated rehearsal.

Those who practise philosophy in the right way are in training for dying.Phaedo, 67e

Phaedo, 64a, 102a-107b · Republic, X, 614a-621d (myth of Er)

The whole order of things is directed toward the Good, the principle and end of all reality: in the Timaeus the Demiurge fashions the world as beautiful and good as possible by looking to the eternal model. Human life finds its meaning in this cosmic teleology, by becoming as far as possible like the divine and the order of the whole.

Timaeus, 29d-30c, 47a-c · Republic, VI, 505a-b

The appetites form the lowest part of the soul and must be mastered and curtailed under reason's guidance, for a soul given over to its desires becomes a "leaky jar" that nothing can fill. Plato preaches not the extinction of desire but its redirection: sublimated erōs becomes the drive that carries the soul toward the Beautiful and the Good.

Gorgias, 493a-494a · Republic, IX, 571a-580a

In the Phaedo, the body is the tomb of the soul: it hinders it, deceives it through the senses and turns it away from the contemplation of truth. The philosopher practises dying, that is, separating soul from body. The true self is the soul.

Phaedo, 64a-67b

In the Symposium, Diotima defines erōs as desire born of lack: child of Penia (Poverty) and Poros (Resource), love desires what it does not have and strives to possess it. This upward drive rises from beautiful bodies to Beauty itself, which lends a residual weight to gift.

Symposium, 199c-204c · Phaedrus, 244a-257b

The Republic builds the just city in thought, an ideal model ruled by the Form of the Good, with its three classes, community of property and of women among the guardians, and education as the art of turning the soul. This is an avowed normative utopianism: the actual city must conform to the paradigm, not the reverse.

Republic, II-V, 369a-473e · Republic, IX, 592a-b

The argument proceeds by analogy with the technai, the crafts: one entrusts the helm not to the many but to the pilot who knows, and a ship where the crew elected its captain by acclamation would be deemed mad. Governing is likewise a knowledge, that of the Good and of justice, acquired only through a long education. From this Plato infers, against the Athenian democracy that condemned Socrates, that authority must fall to competence and not to the opinion of the greater number. The thesis cuts all the deeper for striking at his own city's ruling regime.

Republic, V, 473c-e · Republic, VI, 488a-489d (the ship metaphor)

Platonic ethics is an ethics of virtue: a person's good lies in the state of the soul, and justice is defined as the harmony of its three parts, each performing its own function under the rule of reason. The good life is not a matter of rules or of calculating consequences but of an ordered, virtuous character.

Republic, IV, 441c-444e · Gorgias, 506c-508c

Against the relativism of Protagoras, for whom "man is the measure of all things", Plato grounds values in objective Forms, the Just itself and the Good itself, which depend on neither convention nor opinion. Good and justice are universal and real, knowable by reason.

Theaetetus, 152a, 170a-172b · Republic, VI, 504e-509b

The Republic examines justice first in the city, "writ large", in order then to read it in the soul: the political whole is prior and illuminates the individual part. The city is an organism in which each class is a member, and the common good takes precedence over private interest, to the point of abolishing property and family among the guardians.

Republic, II, 368c-369a · Republic, V, 462a-466d

The sensible, in perpetual becoming, cannot be an object of knowledge: nothing stable is to be found in it to know. What really is are the intelligible Forms, immutable and eternal, of which changing things are only participations. Yet Plato grants becoming its own consistency: the sensible world is not nothing, it is a moving image of eternity.

What is that which always is and has no becoming, and what is that which is always becoming and never is?Timaeus, 27d

Timaeus, 27d-28a · Republic, VI-VII · Cratylus, 439c-440

The argument starts from a premise inherited from Heraclitus: the sensible is in perpetual flux, and of what never ceases to become there can be no science. Yet since we do know the equal, the just, the circle, there must exist stable, intelligible objects of which sensible things are only imperfect reflections: this is the higher degree of reality. The allegory of the cave, where prisoners take shadows for the real, dramatizes this reversal. A dualism Plato never dissolves remains, two distinct orders held side by side, whose relation of "participation" stays problematic, as he himself concedes in the Parmenides.

To them, would not the truth be literally nothing but the shadows of the artificial objects?Republic, VII, 515c

Republic, VII, 514a-518b (allegory of the cave) · Timaeus, 27d-29d

The analogy of the sun carries the argument: just as the sun makes things visible and makes them grow, the Good gives the Forms their being known and their being at all. As the cause of both intelligibility and existence, the Good cannot itself be one essence among others: it surpasses them, set "beyond essence". Plato thus pushes transcendence to its extreme, against any immanence that would lodge the principle within the world, and makes the whole of dialectic an ascent, out of the cave, toward this separate principle that the soul beholds only at the price of a conversion of its gaze.

The Good is not being, but still beyond being, surpassing it in dignity and power.Republic, VI, 509b

Republic, VI, 508e-509b · Symposium, 210a-212a

The Timaeus presents a Demiurge, a good craftsman-god who orders the world by looking to the Forms as models; the Laws assert the existence of gods and providence against atheism. This rational, impersonal theism, with no creation ex nihilo and no single God in the monotheist sense, holds the score back from the extreme.

Timaeus, 28a-30c · Laws, X, 885b-907d

Beauty is neither a matter of taste nor an attribute of things: there exists a Form of the Beautiful, eternal and absolute, which neither comes to be nor perishes, and in which beautiful things participate. This is aesthetic objectivism at its purest, the terminus of the erotic ascent of the Symposium.

Symposium, 210e-211b · Greater Hippias, 287c-289d

The soul is tripartite and reason must govern it: the image of the winged chariot in the Phaedrus shows the charioteer (intellect) mastering the obedient horse (spirit) and the unruly horse (appetite). The passions are not guides but forces to be disciplined and ordered under the command of logos.

Phaedrus, 246a-254e · Republic, IV, 439d-441c

Art is mimēsis, imitation: painter and poet copy sensible things, which are themselves copies of the Forms, thus producing an image at the third remove, far from the truth. This definition of art as reproduction, not creation, grounds the critique of the poets and their banishment from the city.

Republic, X, 595a-602c · Sophist, 235d-236c

Beauty plays a unique anagogic role: it is the only Form that shines forth in the sensible and, through erōs, sets the soul moving toward the intelligible. Yet it remains subordinate to the Good and to justice: seductive poetry is banished from the city if it corrupts the soul, and the beautiful is valuable only insofar as it leads to the true and the good.

Phaedrus, 250d-251b · Republic, III, 401b-403c

Art is never judged by the pleasure it gives but by its truth and its moral effect: mimetic poetry is condemned for flattering the soul's lower part and straying from the truth. Conversely, the Republic admits a regulated music and stories that shape character and tune the soul to harmony, making art an instrument of formation.

Republic, X, 605a-608b · Republic, III, 398c-401d

There is an objective hierarchy of pleasures and of the soul's objects: in the Republic, only the philosopher, who has tasted all three kinds of pleasure, can judge which are truest, and his verdict ranks the pleasures of knowledge highest. Pleasures are not of equal worth, and competence to rank them belongs only to the well-ordered soul.

Republic, IX, 580d-583a · Philebus, 51a-53c