Protagoras

A lively dialogue set at the house of the wealthy Callias, where the leading sophists of Greece have gathered. A young Athenian, Hippocrates, wants to study with Protagoras, and Socrates goes with him to ask what exactly Protagoras teaches. Protagoras says he teaches civic virtue, and when Socrates doubts that virtue can be taught, he answers with a long speech: a myth in which Zeus gives justice and a sense of shame to all humans, followed by an argument about how a city teaches its citizens. The two then argue over whether the virtues are one or many, quarrel about long speeches against short answers, and debate the meaning of a poem by Simonides. In the final part Socrates argues that no one does wrong knowingly, that being overcome by pleasure is really a mistake in measuring pleasures and pains, and that virtue is knowledge. By the end each has swapped positions.

It gives the sophists their strongest voice in Plato and contains the classic Socratic denial of weakness of will, still a live topic in moral psychology.