Plato (427–347 BC) was born in fifth-century Athens to a wealthy family. A young Athenian of his station would have been expected to pursue politics, but instead Plato followed the path of his mentor, Socrates (470–399 BC), and became a philosopher.

Plato’s philosophical writings are dialogues in which two or more characters discuss a philosophical issue. The main character in most of Plato’s dialogues is Socrates. Since Plato never speaks in the dialogues, scholars face the question: How much of what Plato puts into Socrates’ mouth is Plato’s own philosophy, and how much is just a report of Socrates? Many scholars believe Plato’s earlier dialogues are historically accurate accounts of Socrates’ teachings. Later, they believe, Socrates became a literary character for Plato’s own purposes.

Plato is best known for his theory of forms—abstract, immaterial things imitated by the physical objects of this world.

Another famous Platonic view is that all knowledge is recollection. Plato believed the soul was immaterial and existed before it inhabited a body. Before it was embodied, the soul knew the forms, without being distracted and limited by sensory perception. When human beings come to know something, it is because our souls recollect what they knew before they were embodied.

Furthermore, Plato divided the soul into three parts: the appetitive part (which desires sensual pleasure like food, drink, and sex), the spirited part (which desires glory and honor), and the rational part (which desires to understand the forms). In the dialogue The Republic, Plato describes what it is for a soul to be just, by drawing an extended analogy between a just soul and a just city. Plato describes the perfectly just city as having groups of citizens that correspond to the three parts of the soul. He believed those groups must harmoniously interact in the same way that the three parts of the soul should. In both cases, the soul and the city, Plato believed that the rational should dominate.


  1. Plato appears only in one of his dialogues, Apology, which describes the trial of Socrates, at which he is sentenced to death. Plato says nothing in the dialogue, but his inclusion indicates that he was present at the actual event.
  2. Plato was the teacher of Aristotle (384–322 BC).

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