Plato's Euthyphro is a short Socratic dialogue about piety, moral authority and the difficulty of defining the standards by which actions are judged right or wrong. It takes place outside the court of the King Archon in Athens, where cases involving religion and homicide were heard. Socrates has arrived to answer Meletus' accusation that he corrupts the young and does not recognise the gods of the city. Euthyphro is there for a very different reason: he intends to prosecute his own father for the death of a dependent labourer.
The meeting gives Plato an exact dramatic setting for the inquiry. Socrates is about to be tried for impiety, while Euthyphro presents himself as unusually knowledgeable about piety and divine matters. If Euthyphro truly understands the subject, Socrates suggests, he could become Socrates' teacher and help him answer Meletus. The request sounds respectful, but it also exposes the distance between Euthyphro's confidence and his ability to explain what he claims to know.
Euthyphro's prosecution arose from a morally complicated incident on the family's farm at Naxos. A hired labourer killed an enslaved household servant while drunk. Euthyphro's father bound the man and left him in a ditch while sending for religious advice about what should be done. Before an answer returned, the labourer died from hunger, cold and neglect. Euthyphro treats the family relationship as irrelevant: pollution caused by an unlawful death must be addressed whether the responsible person is a stranger or one's father. His relatives regard the prosecution itself as impious.
Socrates does not attempt to settle the legal case directly. He asks for the knowledge that supposedly makes Euthyphro certain. The conversation therefore shifts from a disputed example to a general question: what is piety? Socrates wants the single character or form through which every pious action is pious and every impious action is impious. A definition must do more than identify one action that its speaker approves; it must provide a consistent standard capable of guiding judgement across different cases.
Euthyphro's first answer is that piety is doing what he is doing – prosecuting anyone guilty of murder or sacrilege, even a close relative. He supports the answer by appealing to the god Zeus, who punished his own father Cronus. Socrates observes that an example is not a definition. Euthyphro has described an allegedly pious action without explaining the quality shared by all pious actions.
The appeal to mythology also introduces a deeper difficulty. Traditional stories portray the gods disagreeing, fighting and condemning one another. If piety is what is dear to the gods, an action loved by one god and hated by another would be both pious and impious. The definition fails because divine disagreement cannot supply the single stable standard Socrates requested.
Euthyphro refines the proposal: the pious is what all the gods love, while the impious is what they all hate. This produces the dialogue's most influential question. Is the pious loved by the gods because it is pious, or is it pious because the gods love it? Socrates distinguishes a thing's character from what happens to it. Something is carried because someone carries it, and something is seen because someone sees it. In the same way, what is god-loved is god-loved because the gods love it. But if the gods love piety because it is already pious, their love responds to a quality that must be explained independently. Divine approval cannot itself constitute that quality.
This reasoning is now commonly associated with the Euthyphro dilemma. In modern form, it asks whether morality is right because a divine authority commands it, or whether the authority commands it because it is right. The first alternative can appear to make morality dependent upon choice alone; the second appears to place a standard of rightness beyond the command. Plato's dialogue does not formulate every later theological version of the dilemma, and its subject is the Greek concept of piety rather than morality as a whole. Nevertheless, the question remains central to debates about religion and ethics.
Euthyphro next suggests that piety is the part of justice concerned with attending to the gods. Socrates asks what kind of attention is meant. Care usually improves its object: horse care makes horses better and medical care benefits bodies. Euthyphro cannot plausibly claim that human piety improves the gods. He therefore redescribes piety as a kind of service, comparable to the work assistants perform for a master. Yet he cannot say clearly what achievement the gods produce with human help.
The discussion then turns towards prayer and sacrifice. Piety appears to be knowledge of how to ask from the gods and give to them. Socrates tests this as a relationship of exchange. Human beings request what they need and offer what the gods value. If the gods gain no practical benefit from human gifts, sacrifices seem to supply honour, gratitude and pleasure. But this returns the argument to what is pleasing or dear to the gods, the definition already shown to be incomplete.
The dialogue ends without an agreed definition. Euthyphro claims that he is in a hurry and leaves. Socrates responds with comic disappointment: he had hoped Euthyphro's wisdom would teach him the nature of piety and help him escape Meletus' charge. The failure is philosophically important. Socrates has not proved that piety is meaningless, nor has he offered a final theory of religion. He has shown that confidence, examples, tradition and appeals to authority are insufficient when their underlying standard cannot be explained consistently.
Euthyphro also prepares readers for Plato's Apology. Socrates is accused of religious wrongdoing by a city whose supposed experts struggle to define the very quality at issue. His method appears at once morally serious and socially unsettling: he asks people to give reasons for authoritative claims and follows those reasons beyond the point at which reputation, custom or confidence can protect them.
For modern readers, the dialogue offers more than a puzzle about divine command. It asks how moral concepts should be defined, whether authority creates value or recognises it, and how certainty should respond to examination. Euthyphro may be sincere in believing that justice requires action against his father, but sincerity does not establish knowledge. Plato leaves the legal decision unresolved so that the reader must distinguish moral courage from untested conviction.
As part of Open Philosophy Library's Socratic sequence, Euthyphro belongs immediately before the Apology, Crito and Phaedo. It shows Socrates outside the courthouse questioning piety; the Apology presents his defence and conviction; Crito examines whether he should escape; and Phaedo portrays his final day. Read in that order, the dialogue introduces both the charge that will lead to his death and the philosophical practice through which he confronts it.