Plato

Plato founded the Academy and wrote the dialogues that set the agenda of Western philosophy. Born in Athens around 428 BC into an aristocratic family with connections on both sides of the city's politics — his relatives Critias and Charmides were among the Thirty Tyrants — he was expected to enter public life. Two things prevented it. The conduct of the Thirty in 404 BC disgusted him, and the restored democracy executed Socrates in 399 BC on charges of impiety and corrupting the young. He concluded that no existing constitution was sound and that philosophy alone offered a remedy. He travelled for years, to Egypt, Italy and Sicily, where he encountered Pythagorean mathematics, and around 387 BC founded the Academy outside Athens, which operated for some nine centuries. He wrote in dialogue, almost never in his own voice, with Socrates usually the questioner. The early dialogues examine definitions and end without answers. The middle ones set out his own positions: the theory of Forms, which holds that the objects of knowledge are unchanging realities of which physical things are imperfect copies; the tripartite soul; and the argument of the Republic that a just city would be governed by philosopher-rulers, with censorship, communal property among the guardians, and equality of education for women. The allegory of the cave is in book seven. He tried three times to influence Dionysius II of Syracuse and failed, once being sold into slavery on the return journey. The late dialogues criticise his own theory of Forms. Aristotle studied with him for twenty years. He died around 348 BC.

• Lived: 428 BCE – 348 BCE
• Nationality: Greek
• Roles: philosopher, writer