Euthyphro of Prospalta (Εὐθύφρων Προσπάλτιος) was an Athenian religious prophet (mantis), farmer, and jurist. His sole documented appearance in history is in Plato's biographies of Socrates, wherein Euthyphro encounters the sage during the last few years of the latter's life. Euthyphro, who professes extreme piety, tells Socrates that he intends to prosecute the trial of his own father, who is accused of murder, because the gods' law demands it. Seeking a definition of the word "piety", Socrates asks Euthyphro a set of rhetorical questions about the gods and their laws. One of these questions is known as the "Euthyphro dilemma" or "divine command theory of morality", and is often applied by philosophical theologians to the monotheistic God rather than the polytheistic Ancient Greek gods. It is usually worded as "Do the gods command something because it is good, or is something good because the gods command it?"
Euthyphron was one of the Athenian hoplites who invaded Sicily under Alkibiades' command. While waiting in a chow line, Euthyphron discussed important matters of faith with another hoplite, Sokrates. The latter claimed to be very simple-minded, and hoped that Euthyphron could help him understand the complicated logic of the gods' laws. Sokrates asked "Do you say deeds are unholy because the gods hate them, or do you say the gods hate them because they are unholy?" Euthyphron replied "I certainly do," and a third man pointed out that it was a question of one or the other, and that Euthyphron could not have it both ways. Euthyphron tried to have it both ways anyway, but Sokrates' questions wouldn't let him. Euthyphron was so dazed and confused that he left the chow line without being served. When another hoplite accused Sokrates of tying Euthyphron up in knots, Sokrates replied that Euthyphron's thinking was already not straight, and that the questions were intended to help Euthyphron root out the truth.