Book 1 of Plato’s Republic raises the question what is justice? Four views of justice are examined.

The first is that justice is speaking the truth and paying one’s debt. The second is that justice is helping one’s friends and harming one’s enemies. The third view of justice is that it is to the advantage of the stronger. The last view is that injustice is more profitable than justice.The book begins by explaining that at the time many Athenians are celebrating the introduction of a new goddess at the city of Piraeus.

Socrates and a companion, Glaucon, are returning from the festivities when Polemarchus see them. Polemarchus insists that they come to his home for some conversation with his friends and Socrates agrees. He cannot resist an opportunity to discuss philosophy with a group of noble young people.Cephalus, Polemarchus’s father, is in the house. Socrates sees how old he has grown and wants to know if old age is a difficult part of life.

Cephalus says he is happy to have escaped the all-encompassing bodily pleasures and is now content. He then adds that if he had not had a good character, then he would not be able to enjoy old age. Socrates then asks him if he thinks he endures old age easily because he is wealthy. Is acquiring wealth the most important thing in life? Socrates, who is poor by choice, implies that men like Cephalus often forget about the conditions that make their kind of life possible.
Cephalus admits that his wealth makes it possible for him to live a well-balanced life.

He does not have to deceive others and he is not in debt to any god or any man. Socrates then asks Cephalus is he means that justice is simply telling the truth and honoring one’s debts. Cephalus says that this is what he means. Because of his wealth he can die satisfied, his duty of providing for his family after death fulfilled. Thus, for Cephalus justice is a matter of self-interest, a view that agrees with the laws of the city and the traditional religious beliefs.Socrates objects to Cephalus by asking if there are times when one should not tell the truth or repay debts? Because Cephalus’ definition of justice does not apply in all cases, Socrates says that it is not a good definition.

Suddenly Cephalus says he must leave; there are still debts to be paid to the gods. He refuses to be drawn into a philosophical discussion because it might threaten his beliefs.The tone Socrates uses is casual and the language is simple. This serves to belie the complexity and elevation of the ideas which draws the young men into the conversation by feigned ignorance, only so Socrates can show that he does not know what he thinks he knows. The tone also complements truth and wisdom.

After Cephalus leaves, the discussion becomes more serious and complex. Polemarchus carries on his father’s argument. However, unlike his father he is not concerned with the role of justice in religious matters. Polemarchus relies on authorities other than the gods or laws.

He borrows a saying from a poet that says that justice is “giving every man his due”. Socrates says that he does not know what the poet means, so he asks what is it that is due and who is it due to. Socrates knows, for example, what the functions of medicine and cooking are. However, he does not know what the function of justice is. Polemarchus says that justice is benefiting one’s friends and harming one’s enemies.

Socrates begins refuting Polemarchus’ argument by asking him to explain in what ways justice can be helpful and harmful. Through a series of leading questions (Is the just man more useful than the farmer in producing crops? Than the builder in constructing houses? Etc.) Socrates leads Polemarchus to the conclusion that justice must be useless. Socrates then says that because justice, according to Polemarchus, appears to be the craft of keepers of things not in use (money and property), and because good keepers are in a position to be the best thieves, justice appears to be the craft of thievery, to the benefit of one’s friends.

Polemarchus objects to Socrates’ conclusion. Socrates says that maybe his problem is that he does not know what Polemarchus means by “friend.” Polemarchus responds that friends are those who we think are good and helpful to us. However, asks Socrates, can we be mistaken about who our friends and enemies are? If we can, we may be helping or harming the wrong people, which could not be justice. Thus there is a contradiction, justice can both help and harm friends.

Polemarchus then says that a friend is someone that is good is a friend.Socrates then says that it cannot be a function of justice to harm anyone at all. Do we not consider justice to be an excellence of character? Socrates then says that no excellence – whether of horses or humans – is ever achieved through destructive means. The function of justice is to improve human nature.

Whatever else it is, justice is a form of goodness that cannot participate in anything injurious to someone’s character.
Socrates uses his Socratic method when he seeks to find out what justice is. It is a technique of questions and answers used to discover knowledge. By questioning someone, Socrates refines their definition of something and thus together they reach a better understanding. The flaw of this type of method is that it presumes that Socrates will find the correct answer.

However, what is he does not, as will happen in the question of what is justice? Socrates is able to refute Thrasymachus’ claim that justice is whatever benefits of the stronger by questioning Thrasymachus, but he does not come to any conclusion about justice.Thrasymachus then accuses Socrates and Polemarchus of talking nonsense with all this questioning and answering. Thrasymachus wants to know why Socrates does not just say what he means. Thrasymachus likes to give long speeches without being interrupted by questions. Any other form of teaching, he feels, shows weakness.
Socrates says he is trembling and frightened by Thrasymachus’ outburst.

Socrates then gets Thrasymachus to present his view on justice. But first Thrasymachus wants to be paid for his information. The young men put up the money.Thrasymachus says that justice is the advantage of the “stronger”. Robbery and violence are normally called "injustice," but when they are practiced wholesale by rulers, they are justice, i.e.

the interest of the stronger, the rulers. Thus, when we consider ordinary citizens, “the just man comes off worse than an unjust man everywhere" (343d). Since the rulers do not obey the principles they impose on the citizens, they are in those terms "unjust." Socrates and Thrasymachus agree that the stronger are those who rule and establish the law, and that being just is beneficial. However, they disagree on who is beneficial because they are just.

Is it to the just man himself? On the other hand, is it to the ruler who determines what is just and what is not? Socrates makes the point that if the weak, after all, can prevent the strong from taking what they want or can prevent someone from becoming a tyrant, then they are the strong.For Thrasymachus, being just is obeying the laws of rulers. He then says that rulers make laws for the purpose of increasing their own power and wealth. Thus, just men are weak and powerless in comparison to their rulers.

Socrates then gets Thrasymachus to agree with him that sometimes rulers make errors in judgement and that the ruler’s advantage may be stopped if their orders are obeyed. Thrasymachus limits his claims to saying that rulers who make mistakes are not rulers.Thrasymachus then says that rulers must be guided by knowledge, much to Socrates’ pleasure. Rulers can be considered rulers only when they are performing their proper function.

However, Socrates inquires into what their function is. Is it not similar to the function of other useful arts? Doctors serve the sick; ship captains serve sailors; horse trainers serve horses. Socrates implies that knowing how to serve well is the special knowledge of each profession. Rulers need to know how to serve the interests of the state. Thus, like other professionals, rulers do not pursue their own advantage, but the advantage of those who need their help.
Thrasymachus, upset at Socrates’ refutation of his definition, insults Socrates.

Then he begins a speech, feeling that by using persuasive rhetoric he can win the argument and admiration of the young men. Nonetheless, Socrates’ argument against him was not very strong. However, Thrasymachus’ speech does not help him. He makes a thoughtless comparison between shepherds who fatten sheep for their own appetites and rulers who fatten people for the same reason. He then raises the issue that the greatest happiness belongs to the wrongdoers (tyrants for example), not to those who are wronged.Socrates then says that true rulers do not rule willingly.

He compares the function of rulers to the functions of other professionals. Socrates says that the aim of true rulers is to provide for the welfare of the state and that true rulers are forced into leadership in order to avoid being ruled by people who less ability than them. Socrates asks why should rulers want to rule? Is it better to be provided for than to provide for others? Socrates says that because leadership is such a demanding, thankless job that rulers, like other professionals, deserve financial rewards for their services.
Socrates’ argument shows that leadership is like any other useful profession because it takes special skill and knowledge. Socrates, through whom Plato speaks, uses analogies (rulers are like professionals) to persuade the young men to accept his views.

Although it is persuasive, the young men can still maintain a critical outlook. Comparisons of unlike things can be misleading, unfair, and can cause one to accept as true that which is false.Socrates now looks to find out whether justice is good or bad. Socrates is trying to determine the value of justice before he has defined justice. He does this to keep the attention of his young men because he knows the young grow weary of prolonged discussions.
Socrates then begins to refute Thrasymachus’ claim that begin unjust is wise and good.

Socrates compares the art of living well with the musician’s art. The musician has knowledge of music and in this way is better than the unmusical person. The musician does not want to be superior to or defeat others who share his knowledge; however, he only wants to be superior to the unmusical person. Socrates says the same is true of the just man; he wants to outdo the unjust man but not those of his kind, the just. On the other hand, the unjust man wants to be superior to those like himself and those unlike himself.

The unjust man is selfish and seeks only his own advantage. Socrates says that people who are good and wise do not want to be superior to or get the better of those who are like themselves. Thrasymachus agrees with Socrates. Thus, he concedes that the unjust person cannot be good and wise.

A strange argument, but a happy conclusion.Socrates then sets out to refute Thrasymachus’ next claim, that injustice is power. Socrates shows that injustice cannot be power because there is no loyalty among the unjust, no honor among thieves. Thrasymachus has to agree because based on his earlier statement that unjust people are selfish and so do not readily band together to achieve common goals.

Continual dissension and hostility creates chaos, which is not the achievement gained by those who work together.Next to refute is Thrasymachus’ claim that the unjust are happier than the just. In previous arguments Socrates showed that justice is a virtue, a human excellence. Socrates now has to show that human action that is excellent brings happiness. Socrates says that the excellence of eyes is to see and the excellence of ears is to hear.

Excellence in those things, as with all things, means doing well in performing one’s function. People who do well are blessed and happy. Thrasymachus agrees with Socrates so far. Then Socrates reminds Thrasymachus that he had earlier admitted that justice is an excellence of character.

Thus, is must follow that the just person is the happy person.Socrates then sums up his statements. Injustice is never more profitable than justice, no matter how you argue Thrasymachus. Although Socrates realizes he has refuted Thrasymachus, he also realizes his argument is incomplete. The most important issue – what is the nature of justice – has not been solved. Justice is an excellence of human character and a source of happiness.

However, knowing these things is just a beginning. What is the just life? Therefore, Socrates concludes that more investigation is needed.
Plato does not argue whether it is more moral to live justly, but rather whether it is more beneficial, whether the just life will make one happier.
Republic by Plato