Summary of Book 1 of Plato’s Republic

by Jonathan McIntosh

The Republic opens with Socrates and Glaucon (Plato’s real-life older brother) present in the Piraeus, the harbor area of Athens, where they had descended the day before to attend a religious festival in honor of Bendis, goddess of the underworld. As they start on the six-mile ascent back to the city of Athens proper, they are detained by Polemarchus and his gang of friends, including another of Plato’s real-life brothers Adeimantus, who invite Socrates and Glaucon to return with them back to Polemarchus’s house.

There they meet Polemarchus’s aged father Cephalus who is in the midst of performing sacrifices in the courtyard. Socrates and Polemarchus immediately fall into a conversation about old-age, the greatest benefit of which, Cephalus claims, is that a man is no longer driven mad by his youthful lusts and other bodily appetites. Socrates asks if the real reason Cephalus doesn’t bear old age so well, on the contrary, is because of his great wealth, which leads into a discussion of wealth and wealth acquisition. Cephalus claims that the greatest blessing he has received from his wealth is that he is able to afford to face death without fear of the afterlife since he has no need to cheat or deceive anyone or neglect any sacrifices he may owe to the gods. Socrates responds that, on this account, then, justice would seem to be speaking the truth and paying one’s debts. To this implicit definition Socrates offers the counterexample of a man who owed a sword to a friend who was mad: repayment in this instance, and yet in contradiction to Cephalus’s definition, would not be justice but injustice.

At this point Cephalus bows out of the discussion and his son Polemarchus “inherits” his father’s definition of justice, but which Polemarchus now revises to say that justice is doing the good that one owes to one’s friends and doing the harm that one owes to one’s enemies. The difficulty Socrates finds with this definition is that it suggests the counterintuitive conclusion that the just person is the one best able to steal from or commit other acts of injury against others. It also doesn’t take into account that people can be and often are mistaken about the goodness or badness of their friends or enemies, in which case justice could, by Cephalus’s definition, involve doing good to people who are bad and harm to people who are good. Cephalus at this point revises the definition of a friend and an enemy, saying that justice is now doing the good that one owes to one’s friends when the latter are objectively good and doing the harm that one owes to one’s enemies when the latter are objectively bad. The trouble Socrates finds with this is it still involves justice in doing harm to someone and so making that person worse than they were before, something that justice does not and would not do.

Thrasymachus, a sophist who teaches the art of persuasion for pay, here ferociously interjects himself into the conversation, startling Polemarchus and Socrates, mocking them both and chastising Socrates. He accuses Socrates of being disingenuous in playing his question-and-answer game in which he breezily faults the definitions given by others but doesn’t do the hard work of offering an alternative account of his own. Socrates protests his innocence, and his ignorance, and succeeds in getting Thrasymachus to venture his own definition of justice. Justice, Thrasymachus claims, is nothing else than the advantage of the stronger. This means that in a city justice is a matter of the rulers legislating and ruling to their own advantage, with democracies making democratic laws that benefit the voting public, tyrannies making tyrannical laws that benefit the tyrant, and so forth. To be unjust, accordingly, is nothing else than to go against the laws that happen to have been established by the rulers for their own benefit. To this Socrates raises the counterexample of rulers who inadvertently make laws that are in fact to their disadvantage, in which case obedience to laws, which is one part of Thrasymachus’s definition of justice, would be in conflict with the advantage of the rulers, the other part of his definition.

Similar to Polemarchus’s earlier revision of his definition, Thrasymachus revises his definition of justice to say that it the advantage of a ruler insofar as he is a true ruler, that is, someone who doesn’t merely attempt, but actually succeeds, in legislating in his own self-interest or advantage. To this Socrates counters that, like other kinds of rulers—e.g., a doctor who rules the sick, a captain that rules a ship, horse-breeders who rule horses, etc.—the rulers of people rule their subjects not for their own benefit but for the benefit of those whom they rule. Thrasymachus counters with the example of shepherds and cowherds who fatten their animals, not for the animals’ benefit, but for their owners’ benefit when the animal is slaughtered. But Thrasymachus also revises his definition to say that justice is the good that one does to another, specifically, the benefit conferred on one’s rulers who are stronger, but is something actually detrimental to the one doing the justice. Injustice, by contrast, is the benefit or advantage that the stronger confer on themselves which makes themselves happy but their subjects unhappy.

The rest of book one of the Republic consists in Socrates’s dismantling of Thrasymachus’s revised definition of justice. He begins by noting that in other kinds of rule, the rulers do not rule for their own sake but for the sake of that which they rule, for which reason they require some form of compensation for their trouble. Whatever the art or craft involved, the one exercising it also practices the additional craft of wage-earning by which they profit from their primary craft. Good people, however, won’t want to rule for either money or honor, and so must be compelled to rule, yet the greatest punishment for not ruling is the threat of being ruled by someone inferior to oneself. And so it would seem that Thrasymachus is incorrect when he says that justice is the advantage of the stronger.

As for Thrasymachus’s claim that injustice is more beneficial to a man than a life of justice, Socrates replies with three distinct argument. First, he gets Thrasymachus to identify injustice as a form of virtue, and therefore as something clever, wise, and good, and then to admit that a just person is someone who would want to outdo only an unjust person, whereas the unjust person is someone who seeks to outdo both the just and the unjust. Socrates then points out that the good and clever person is someone who tries to outdo those who are unlike him rather than those who are like him, suggesting that the just man is in fact the good and clever person and the unjust man, by comparison, is bad and ignorant.

Second, Socrates points out how injustice produces factions, hatreds, and quarrels, whereas justice produces unanimity and friendship. When injustice occurs inside a man, consequently, it must render him less capable of action, setting him at odds against himself, and hence making himself weaker rather than stronger, in the same manner as injustice in a city sets one part of a city against itself. Injustice, in short, is something that incapacitates a man (351a-352b).

Third and finally, Socrates raises the question whether it is true that the unjust man lives a better life and is happier than the just man (352d). Regardless of what it is that makes a person stronger or more knowledgeable, the question of justice really boils down to this: how is it that a man ought to live? What, in other words, is the right kind of life for man? To know the answer to this question, we need to understand what it is that gives man the power of life in the first place, and what enables a man to have life is his soul. Everything has its peculiar work or operation, Socrates believes, and the peculiar work of the soul is to live, that is, the act of living. If the work of the soul is to live, however, then it means that the virtues of the soul are those things that enable the soul to live well, to live with excellence. The good soul, in other words, is the virtuous soul, the soul that has learned to live well. If we grant, however, that justice is a virtue, then we can reasonably conclude that a soul without justice, that is to say, without one of its proper virtues, cannot live well, and therefore cannot be a good, prosperous, and profitable soul. For this reason, Socrates at last concludes book one, injustice cannot be something more beneficial or good than injustice.

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