Who Influenced Plato's Education? Socrates, Protagoras, the Pythagoreans and Homer

This page covers four influences on Plato’s education and thought, not a ranked list of ten: Socrates, the sophist Protagoras, the Pythagoreans, and the poet Homer. The evidence for each is uneven. For some of them we rely on what Plato himself says, and for others on later reports. A fuller treatment of the background is in the key influences on Plato’s education.

An earlier version of this page listed “philosopher-kings” and Alcibiades among the influences. A philosopher-king is a concept in the Republic, not a person, and Alcibiades does not appear in the Republic at all.

Socrates

Socrates (c. 470-399 BC) was Plato’s teacher in the sense that matters most, though the details of their relationship come only from Plato and from Xenophon. Plato names himself as present at Socrates’ trial (Apology 34a) and wrote most of his dialogues with Socrates as the leading speaker. Our evidence for the historical Socrates is almost entirely through Plato, Xenophon and Aristophanes, so how much of the “Socrates” in the dialogues is Plato’s own philosophy is debated. Aristotle (Metaphysics 987b) credits Socrates with the search for definitions of ethical terms, which Plato took further into a theory of Forms. See how Socrates mentored Plato.

Protagoras

Protagoras (c. 490-420 BC) was the most famous of the sophists, the paid teachers of rhetoric and public life in fifth-century Athens. He is credited with the saying that “man is the measure of all things”, which Plato reads in the Theaetetus (151e-152c) as the claim that things are for each person as they appear to that person. Plato wrote a dialogue named after him, the Protagoras, and discusses his view at length in the Theaetetus.

Protagoras was an influence mostly as an opponent. Plato argues against his relativism, including a well-known argument in the Theaetetus (169d-171c) that the view undermines itself. It would be a mistake to say that Protagoras led Plato to the Forms, as some summaries put it. Aristotle’s own explanation (Metaphysics 987a29-b10) is that Plato was moved to the Forms by the combination of a Heraclitean view that sensible things are always changing, which came to him through Cratylus, and Socrates’ search for stable definitions. See who Protagoras was and Heraclitus’ influence on Plato.

The Pythagoreans

Pythagoras (c. 570-495 BC) left no writings, and what is said about his own doctrines comes from much later reports. Historians therefore speak of “the Pythagoreans” as a tradition in southern Italy, which included Philolaus and, in Plato’s lifetime, Archytas of Tarentum. Later biographers (Diogenes Laertius III.6, 18-22) say Plato travelled to Italy and Sicily and met Pythagorean thinkers there. Aristotle (Metaphysics 987a29-31) says that in most respects Plato followed the Pythagoreans, though with features of his own.

The clearest evidence is in Plato’s own work. The mathematical studies he assigns to future rulers in the Republic (522c-531c), including arithmetic, geometry, astronomy and harmonics, and the number-based cosmos of the Timaeus, show a strong mathematical interest that is often connected with Pythagorean thought. How much he took directly, and how much he developed himself, is disputed. It is an overstatement to say, as some summaries do, that the Forms are “a direct reflection” of Pythagorean beliefs. See Pythagorean mathematics in Plato.

Homer

Homer’s epics were the common text of Greek education. Boys learned lines of the Iliad and Odyssey by heart, and Plato was no exception. In Republic X (595a-c) Socrates says he has loved and respected Homer since childhood, yet he must still speak against him. That is exactly what Plato does. In Books II and III the stories that Homer and Hesiod tell about the gods and the fear of death are criticised for their effect on the young (377d-392c), and in Book X poetry is criticised as imitation at several removes from the truth. Plato’s city would admit only hymns to the gods and praise of good men, unless poetry could make a defence of itself (606e-608b).

The popular claim that Plato simply “banned Homer” is half true, since the city keeps no Homer as it stands. But the passage shows divided feelings, not a plain rejection. See Plato’s critique of poetry.

What about Plato’s early school teachers?

Diogenes Laertius (III.4-5) names a teacher of letters (Dionysius) and the wrestler Ariston of Argos, and says Plato took up painting and poetry; later sources add a music teacher, Draco. These stories come from long after Plato lived and cannot be verified. Aristotle’s report that Plato knew the Heraclitean Cratylus in his youth (Metaphysics 987a32) is much earlier, so they are best read as the later tradition’s idea of a well-born Athenian’s schooling.

Summary

• The four influences covered here are Socrates, the Pythagorean tradition, Homer (as the cultural starting point) and Protagoras (as a target of Plato’s arguments).
• Heraclitus, through Cratylus, is the other influence Aristotle names.
• Alcibiades and the philosopher-kings do not belong on a list of Plato’s teachers.