portrait of Plato


Ancient philosophy

Platon (424-347 BC) was a Greek philosopher from Athens. A disciple of Socrates, he wrote a series of dialogues featuring Socrates. Late dialogues such as The Republic include the famous Platonic doctrine of the Ideas, which distinguishes between two realities, the sensible world, that which we see, and the intelligible world, or world of Ideas. He was sold into slavery by the tyrant Denys of Syracuse and later freed. He founded a school, the Academy, and Aristotle was his disciple.

Plato's works summarised on this site

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The Republic

In The Republic, Plato imagines the principles that would govern an ideal City. This is an opportunity for him to set out the famous Platonic doctrine of the Ideas.


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At a banquet, Socrates and the other guests decide to take turns speaking in an attempt to define what Love is.



Here are the essential books if you want to better understand this author's thought:

Fine, Gail (1999), Plato 1: Metaphysics and Epistemology, Oxford University Press
Dorter, Kenneth (2006), The Transformation of Plato's Republic, Lexington Books
Kahn, Charles H. (1996), Plato and the Socratic Dialogue: The Philosophical Use of a Literary Form, Cambridge University Press
Fine, G. (ed.), The Oxford Handbook of Plato, Oxford University Press
Nails, Debra (2002), The People of Plato: A Prosopography of Plato and Other Socratics, Hackett Publishing

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Biography: life of Plato


Plato was born in Athens in 428 BC, shortly after the death of Pericles, into a wealthy aristocratic family of landowners linked to the ruling oligarchic party.

"Plato" may just have been a nickname (which comes from Platos "breadth") given to him because he was broad shouldered. He was handsome and strong, according to Epictetus. In fact, he is said to have taken part in the Olympic Games and the Isthmian Games as a wrestler, winning two prizes.

According to Diogenes Laërtius, in his youth he was reserved and wise to the extent that he was never seen laughing out loud.

He first devoted himself to poetry, writing tragedies, lyrical verses, etc. He took up painting and music. He was a pupil of Theodore of Cyrene, Socrates' tutor.

Learning philosophy

Then at the age of 20, he met Socrates, and turned to philosophy. He burned all his works and abandoned the idea of competing in Greek tragedy.

He became Socrates' disciple for nine years, from -408 to -399, until Socrates was sentenced to death.

According to Diogenes Laërtius, it is said that Socrates had a dream: he saw on his lap a swan which covered itself with feathers and flew away. The next day, Plato came to join him as a disciple. And Socrates declared that Plato was the bird he had seen in his dream.

He began writing his dialogues, featuring Socrates, while the latter was still alive. Following a public reading of one of his works, the Lysis, his master exclaimed, How many things this young man makes me say that I have never thought of!.


Socrates practises maieutics, or the art of delivering minds: he does not impose any ideas on them, but presses them with questions until an idea forms in their minds.

He is often ironic about his interlocutors, because they think they know something, whereas Socrates for his part says he knows nothing. Through his disconcerting questions, he reveals to them the inanity of their supposed knowledge.

Socratic dialectic is the name given to this way of asking questions in order to make progress in the search for truth.

Plato's early dialogues are devoted to the search for essence. They are questions of definition: "What is X?". For example, in the Euthyphron, what is piety? In the Hippias Major, what is beauty?

He develops a scathing critique of the sophists: he criticises them for getting paid, for having developed mere rhetoric rather than genuine wisdom, for abandoning the search for truth for mere subjectivism (which Protagoras's formula man is the measure of all things would express).

the statue of Plato at the Academy of Athens
The statue of Plato in Athens, in front of the Academy

This period lasted nine years, at the end of which Socrates was sentenced to death by an Athenian court for "corruption of youth". This was because philosophising was viewed with suspicion, as a means of spreading dangerous ideas in the City.

Sick, Plato did not attend Socrates' death. Thinking that he himself might be arrested, he fled Athens, along with a few other disciples, and took refuge in Megara, a town a few dozen kilometres away.

The theory of the Ideas

He then became attached to Cratylus, a disciple of Heraclitus, but also to Hermogenes, who passed on to him the wisdom of the Eleates and in particular of Parmenides. It should be noted that according to Aristotle, Plato was a disciple of Cratylus before he was a pupil of Socrates, but for Diogenes Laërtius and other historians, the opposite is true.

These various influences nourish his thinking. From Heraclitus, in particular, he learnt that the sensible world, the world we perceive, is subject to permanent change, and that nothing fixed remains (No man ever steps in the same river twice). He discovers the aporias of movement raised by the Eleates, and Parmenides' interest in the question of being and non-being.

Here is what Diogenes Laërtius says of these various philosophical influences:He made a synthesis of the theories of Pythagoras, Heraclitus and Socrates, taking from Heraclitus his theory of sensation, from Pythagoras his theory of intelligence, from Socrates his politics.

Plato then developed his own doctrine, based on a dualism between two realities, the sensible world and the intelligible world: the theory of Ideas.

The sensible world changes, degrades, perishes. We must therefore imagine a second reality, eternal, incorruptible, which contains the Ideas or essences. For example, in the sensible world, a beautiful boy grows old and dies, but the Idea of Beauty, in the intelligible world, remains eternal.

The supreme Idea is the Idea of the Good. We contemplated the Ideas in a previous life, and we remember them by reminiscence.

Plato continues to use Socrates as a mouthpiece for his theory, whereas the real Socrates never supported such an idea.

In 395 BC, back in Athens, he took part in the war against Corinth, as a cavalryman, which ended with the Athenians losing to Sparta.


In 390, he travelled: he went to Egypt, where he met the priests of the high clergy.

It is not certain that this trip actually took place, as Plato seems to develop only an indirect and limited knowledge of Egypt.

He also travelled to southern Italy, to Taranto, where he met Pythagoreans (Philolaos of Crotone, Archytas of Taranto...). He discovered this doctrine, which showed him that beneath sensible reality lay another reality, mathematical and permanent, that of number.

He then travelled to Sicily. Plato had given up political life early on, because of the excesses of the dictatorship of the Thirty Tyrants, and the condemnation of Socrates. This was not without regret, since for him political life appeared to be the crowning achievement of the philosophical life.

Plato saw Sicily as an opportunity to devote himself to politics. He tried in vain to persuade Denys, the tyrant of Syracuse, to adopt certain reforms, inspired by philosophy. He failed, and eventually fell out with the latter.

As Diogenes Laërtius relates: Platon discussed tyranny with him, and constantly repeated to him that what was only useful to a man was not a good, if that man was not very virtuous. By this he offended Denys, who became angry and said to him: "You speak to me like an old man! - And you talk like a tyrant," replied Plato. Thereupon, more irritated than ever, the tyrant rushed to have him killed, but at the request of Dion and Aristomenes, he contented himself with handing him over to the Spartan Pollis, who was at the time on embassy in Sicily, to have him sold as a slave.

Platon, reduced to the status of a slave, was redeemed and freed by a disciple of Socrates, Annikeris.

As he refused to be repaid, the ransom money was used to acquire land in Athens. On this land a school was founded. As it was located near the sanctuary of the hero Academos, it was called the Academy for this reason.

The Academy

Platon taught for forty years in this school which he founded.

It welcomed and trained such prestigious pupils as Aristotle, Demosthenes, Theophrastus, Xenocrates...

The subjects studied? Philosophy, of course, but also mathematics and astronomy, two disciplines considered by Plato to be of paramount importance. Indeed, Plato had this phrase engraved on the pediment of the Academy: Let no one enter here who is not a geometer.

Zoology and botany were perhaps also taught.

This was the first philosophical school organised as a university, in the modern sense of the word, with rules, student accommodation, a library, a lecture hall, etc.

The oral teaching was considered the most important. Only limited interest was given to written transmission.

In -366, Aristotle entered the Academy, at the age of seventeen, for twenty years of study.

According to Diogenes Laërtius, This Aristotle was the only one [...] to listen to Plato reading his treatise on the soul; all the other listeners left before the end.

The school endured for nine centuries, until the reign of the Byzantine emperor Justinian, who put an end to it in 529.


On the death of Denys I, Dion, the tyrant's brother-in-law, offered to come and educate his successor, Denys II.

Platon had just completed the Republic in 372BC, a work in which he reaffirmed the need to entrust political power to the philosopher-king. Here again he saw an opportunity to put his principles into practice, and to establish a genuinely philosophical power.

However, Dion was suspected of plotting by Denys II, and Plato, on whom royal distrust also fell, was detained for a year in prison.

It was in 360BC that Plato's third and last political trip to Sicily took place. Recalled by Dionysius II, Plato, aged sixty-eight, entrusted the Academy to one of his disciples and travelled to Syracuse. Here again, relations with the tyrant were conflictual, and only the intervention of a warship sent by the Pythagorean Archytas enabled him to be freed.

Death and influence

Towards the end of his life, it seems that Plato delivered a much more Pythagorean teaching, centred on mathematics and the Ideal Numbers.

He had in fact bought three works concerning the works of Pythagoras at a high price during his last trip to Sicily, which enabled him to deepen his knowledge of this doctrine.

Plato died in Athens in 347 BC, during a wedding meal. He was then deep in the writing of Laws.

After his death, he was deified, and considered a son of the god Apollo.

Plato's works have all been preserved. Nevertheless, in the Middle Ages, few of them were translated into Latin, and so only a few were read at that time (in particular the Timaeus).

All are dialogues, with the exception of the Apology and the Letters. They are commonly classified into three categories: dialogues of youth, maturity and old age.

Main works

The Apology of Socrates
The Republic