Plato

Key ideas

1. The Forms. Beside the many beautiful, equal or just things we meet there is, for each, one Form: eternal, unchanging and grasped by thought, not by the senses. Particular things have their character by sharing in the Forms, and they fall short of them, which is why Plato makes the Forms, and not the particulars, the objects of knowledge.
2. Knowledge and belief. Knowledge is of what completely is, the Forms; belief is about the changing things of sense, which can seem both beautiful and ugly. The Divided Line and the Cave in the Republic picture the ascent from images and perceived things to mathematical reasoning and then to direct intellectual grasp of the Forms.
3. Recollection. In the Meno and the Phaedo, learning is recollection: the soul saw the Forms before birth, and good questioning recovers what it once knew. The doctrine answers the puzzle of how anyone can inquire into what they do not already know, and it presupposes an immortal soul.
4. The tripartite soul. In the Republic the soul has three parts, reason, spirit and appetite, which can pull against one another. A person is just when reason rules, spirit supports it and appetite obeys, each part doing its own work.
5. Justice in the city and the soul. The ideal city has three classes, rulers, auxiliaries and producers, matching the three parts of the soul. The Republic argues that justice is worth choosing for its own sake, whatever reputation or reward goes with it, because it is the health of the soul.
6. The Good and the philosopher-rulers. Only those who know the Form of the Good, which Plato compares to the sun that makes visible things seen, can rule well, and they must be compelled to rule. The late Laws turns instead to a workable constitution of law for cities whose citizens are not fully virtuous.
7. Imitation and poetry. The Republic criticises poetry and the imitative arts as copies of appearances, at several removes from the truth, which excite emotion and weaken the rule of reason. It would admit only carefully chosen verse into the ideal city.

Plato (c. 428–347 BCE) was an Athenian philosopher, a follower of Socrates, the teacher of Aristotle and the founder of the Academy. His complete works are believed to have survived, which is true of almost none of his contemporaries, and metaphysics, epistemology, ethics and political philosophy still take many of their questions from his dialogues.

He was born in Athens, probably in 428 or 427 BCE, into a wealthy and politically active family. A tradition reports that his given name was Aristocles and that “Plato” began as a nickname. Socrates was executed in 399 BCE, and Plato then left Athens. Around the age of forty he visited Italy and Sicily, where he met the tyrant Dionysius I of Syracuse and taught Dion, who became a lasting friend.

He founded the Academy, in a grove outside the city walls, in about 387 BCE. Aristotle studied there from about the age of eighteen. Plato died in Athens in 348 or 347 BCE, aged about eighty, and was buried at the school.

How should the dialogues be read?

Plato wrote dialogues and never speaks in his own voice. Scholars usually sort them into early, middle and late groups. In the early ones, such as the Euthyphro and the Crito, Socrates cross-examines people about virtue and ends without a doctrine. The middle dialogues (the Phaedo, Symposium, Republic) develop the theory of Forms, and the late ones (the Timaeus, Laws) are more technical.

The grouping is not certain: the Stanford Encyclopedia of Philosophy notes that scholars dispute whether it matches the order of composition, and where the historical Socrates ends and Plato begins. So “Plato holds” below means “the dialogues present, usually through Socrates”.

What are the Forms?

The best-known doctrine is the theory of Forms. Many things are beautiful, equal or just, and Plato argues that for each there is one Form, Beauty itself or Equality itself, eternal and unchanging. Particular things are beautiful by sharing in the Form, and they fall short of it: one thing can look beautiful in one respect and ugly in another. This is his answer to the problem of universals.

The Forms are the objects of knowledge; the changing things of the senses are objects of belief. The allegory of the cave (read the passage) pictures the climb from shadows to the sun, which stands for the Good.

Recollection explains how we can know the Forms at all. In the Meno, Socrates answers the puzzle of how anyone can inquire into what they do not know by saying that learning is recollection: the soul saw the Forms before birth, and a slave boy, questioned about geometry, turns out to know more than he was taught. The late Parmenides raises objections to the Forms, and scholars debate how far Plato revised the theory.

What is justice, in the soul and in the city?

The Republic asks whether it is always better to be just than unjust, even with no reward and a bad reputation. Thrasymachus says that justice is the advantage of the stronger. Glaucon sharpens the challenge with the ring of Gyges, which makes its wearer invisible. The library has Republic, Books I–II.

Socrates answers through an analogy between city and soul. The city has three classes and the soul three parts: rulers and reason, auxiliaries and spirit, producers and appetite. Justice is each part doing its own work. The just soul is in harmony, the tyrant’s is enslaved to its desires, and Plato concludes that justice is good for its possessor: the soul that functions with aretē, excellence, enjoys eudaimonia, flourishing.

Only those who know the Form of the Good can rule, Socrates says: “Until philosophers are kings, or the kings and princes of this world have the spirit and power of philosophy … cities will never have rest from their evils” (Jowett’s translation). Karl Popper charged that this amounts to totalitarianism, and the charge is still contested. The late Laws gives up philosopher-rulers for a constitution of law.

Love, piety and the cosmos

The Symposium ends with Diotima’s ladder of love, rising from beautiful things to beauty itself, “absolute, separate, simple, and everlasting” in Jowett’s words. The Euthyphro gives us the Euthyphro dilemma. The Timaeus tells how a divine craftsman ordered chaotic matter in the image of the Forms, and Book X of the Republic attacks poetry as mimesis, imitation at several removes from the truth.

What came after him?

Through Neoplatonism, which began with Plotinus, Plato shaped Christian, Jewish and Islamic thought: Augustine, al-Farabi and Ibn Sina all draw on him. Alfred North Whitehead wrote in Process and Reality (1929) that “the safest general characterization of the European philosophical tradition is that it consists of a series of footnotes to Plato”. He meant, he explained, the general ideas scattered through the dialogues, not a settled system.

How should you start reading Plato?

Begin with the Apology, the Euthyphro and the Crito, all short, and then the Meno. Then take the Republic, from Book I through Book VII, with the Phaedo and the Symposium. The Phaedrus holds his doubts about writing. Leave the Timaeus and Laws until later.

All of these are free on Project Gutenberg in Jowett’s nineteenth-century translation; use a modern one alongside it for close work.