There is a scene in Plato that contains, in miniature, the catastrophe of Athenian public life. Two men meet at a courthouse. One is there to prosecute his own father for the death of a slave. The other is there to be indicted for indecency. [1] The prosecutor, Euthyphro, is certain he understands what decency requires. The accused, Socrates, is not certain of anything, and says so. They talk. Euthyphro’s confidence is striking. His own family thinks it is indecent for a son to prosecute his father; Euthyphro insists that true decency demands it, that he understands what the gods require better than his relatives do.

Socrates, who is about to be tried for teaching indecency toward the gods, asks Euthyphro to explain what decency actually is, since Euthyphro claims to know, and Socrates will need such knowledge for his own defense. Euthyphro’s first answer is: decency is what I am doing right now, prosecuting wrongdoers regardless of kinship. Socrates points out that this is an example, not a definition. There are many decent acts; what makes them all decent? Euthyphro tries again: decency is what the gods love. But the gods disagree among themselves, Socrates observes, so by this…