Although Plato (427–347 B.C.E.) is perhaps the most influential and highly revered philosopher in the Western tradition, and thousands of philosophical careers have been based on his ideas, little is known about his life, with certainty. This is partly because there was a convention in Plato’s time that philosophers writing about their contemporaries not mention them by name. Nevertheless, there is agreement on some broad facts about Plato’s life. Plato, for instance, was present at Socrates’ trial and began his own philosophical works about 15 or 20 years later. Plato was the scion of a politically well-placed, rich aristocratic family who were anti-democrats. At first, Plato envisioned a political career for himself, but after the democrats gained power and Socrates was sentenced to death, he prudently avoided politics.

Plato served in military campaigns in the war against Sparta and was probably in the cavalry. In the 380s B.C.E., he traveled to Egypt and Syracuse in Sicily. Plato went to Syracuse three times as guest of the tyrant Dionysius the Elder, and then of his son Dionysius the Younger. Both father and son were thought to be interested in Plato’s ideas about government, but the results of Plato’s involvement in Sicilian statecraft are usually referred to as “disastrous.” Plato never married, and when he died at the age of 81 he was relatively poor.