The Republic Book 1
Socrates tells that he and his companions went to the Piraeus to watch the procession and festival for the goddess with Glaucon, and that Polemarchus, Cephalus' son, saw them and wanted them to stay longer. After informing Glaucon and Socrates of the continuing festivities and horse races to be held that evening, they agreed to stay.
However, prior to the festivities, they went to Polemarchus' house, where they found his two brothers, Lysias and Euthydemus, as well as Thrasymachus, Charmantides, Clitophon, and Cephalus. Cephalus tell Socrates that he should visit them more often, and also tells him how much he enjoys good conversation. However, he is very old and is unable to travel and see Socrates. Socrates agrees to start visiting more often, saying that older people have more knowledge about life than younger people. He enjoys speaking with them more, as they have already lived through most of life, and there is much to be learned from them.
He then proceeds to ask Cephalus whether his journey through life was hard or not. To this, Cephalus answers that, whereas many of his friends complain about old age and not being about to do youthful things, he believes that they make old age a burden, and that old age is in fact not a burden, but instead a relief from bodily desires. He goes on to justify this by saying that if old age was really a bad experience, everybody would be complaining about it, but since he has friends who are most definitely enjoying their old age more than they enjoyed their youth, when people say that old age is a bad experience they are only stating an opinion, and not a fact.
To further the conversation, Socrates says that it is easy for Cephalus to speak that way since he has the luxury of being wealthy, and that other people might be less comfortable in old age if they didn't have money; thus they would disagree with him. To this, Cephalus replies that there are certainly people who would disagree with him, but that "age isn't easy for a good man if he's poor, nor will a bad man ever be cheerful with himself even if he's rich." Book 1, pg. 3, line 332
Socrates then asks Cephalus if he inherited his money or made it himself. He asks this because he presumes, through observation, that people who inherit money are not as fond of it as those who make it themselves, and it is obvious to him that Cephalus is not overly fond of money. Also, self-made people cannot stop talking about money, whereas Cephalus does not speak of it much. Cephalus admits that he inherited most of his fortune, then goes on to answer Socrates' question as to what the greatest good he has enjoyed from being rich is. He says that when a man reaches old age, he begins to think of all the injustices he has done in his life, and begins to worry about dying and being punished for them. Thus, he says, for a reasonable man the greatest value of wealth is that it helps him avoid unintentional cheating or lying. It "keeps him from having to leave life in the fear of owing debts to men or sacrifices to the gods." Book 1, pg. 5, line 331b
In response to this, Socrates asks Cephalus whether he truly thinks that justice is as simple as telling the truth and returning what you receive. To prove his point, he offers the following as an example: if a person receives a weapon from a friend who then becomes insane, would it be just to return that weapon if the friend asked for it back? In this case, what would be justice - giving him his weapon back or not? The two men then agree that telling the truth and returning what you receive cannot be the definition of justice.
However, Cephalus goes to prepare the sacrifice for the festival, and Polemarchus continues the conversation, saying that justice is giving "each his due," thus quoting Simonides, and saying that the weapon should be returned to the owner in the example above. However, Socrates challenges this, and Polemarchus agrees that that would be a mistake. By "due," perhaps Simonides was referring to doing well to your friends. By giving each person his "due," you would also harm your enemy. Thus, justice is helping your friends and harming your enemies.
Socrates then questions: are friends people who seem honest, or people who are honest but don't seem so? To this, he receives the reply that people are expected to love people that they think are honest, and hate those who seem bad. Socrates turns this around by asking about people who make mistakes and think men are honest when they are not, and vice versa. For them, good men are enemies and bad men are friends, and thus justice means helping bad men and harming good ones. However, since it is widely accepted that good men are just and do no wrong, this argument would lead to the conclusion that it is just to injure men who do no wrong; this is the opposite of what Simonides said.
Now Socrates backtracks and redefines a friend as a good man and an enemy as a bad man. Furthermore, he assumes that justice is helping a friend if he's good and harming an enemy if he's bad. Now, Socrates asks Polemarchus if a just man ever harms anyone. Polemarchus says that just men do harm bad enemies. Socrates now challenges that by comparing justice, a human excellence, to the excellence of a horse. By harming a horse, you decrease his excellence. Thus, by harming a person, you decrease their excellence.
However, it does not make sense that a good person makes other people bad, just as it does not make sense that "cooling is a function of heat." Thus, harm can't be a function of the good person, but a function of the opposite, the unjust person. It has thus been proved that it is never just to harm someone. Simonides, the wise man, must have never said that.
Fed up with all the "foolishness," Thrasymachus jumps in angrily and asks Socrates what, precisely, he thinks justice is. Socrates tells him not to be angry since they are trying their best to figure out what justice is, just as they would be trying their best to figure out where gold is. However, since justice is more important than gold, they are searching even harder. Thus they deserve pity and help from Thrasymachus, not anger and resentment. Thrasymachus gets even angrier and accuses Socrates of never speaking what he thinks but only refuting what others think. He finally agrees to speak of what justice is if Socrates will pay him. Since Socrates has no money, Glaucon jumps in and says that all of the others will contribute to the cost of Thrasymachus' speaking. After further accusing Socrates of never teaching, but instead learning from others and never paying them thanks (Socrates says that he thanks people by praising them), Thrasymachus goes on to state that justice is the advantage of the stronger.
Then, Thrasymachus asks Socrates for praise. However, Socrates first wants to understand exactly what Thrasymachus means, and so he looks into his statement.
First, he establishes that justice is what the stronger thinks is to his advantage, rather than what is to his advantage. Then, through considering the function of medicine and comparing it to justice, he establishes that "no knowledge considers or prescribes for the advantage of the stronger, but for that of the weaker, which it rules" Book 1, pg. 17, line 342d. This, in turn, means that no ruler rules for his own advantage, but rather rules for that of his subjects. Having his words turned around, Thrasymachus is angry and states that in any partnership the unjust person always gets the better of the just in every way. The perfect form of injustice is the one that brings happiness to the possessor and misery to others: tyranny. He then goes on to say that the reason men condemn injustice is because they fear suffering it, not committing it. Therefore, he concludes that injustice is stronger and freer than justice, yet justice is the advantage of the stronger.
After saying this, he makes to leave. However, the others stop him from leaving and demand that he explain himself. Socrates says that he doesn't agree that injustice is more profitable than justice. He then asks him if he thinks that rulers of cities truly rule freely. Thrasymachus says that he believes that they do. Socrates then begins examining all other professions, coming to the conclusion that professionals provide benefits to others and practice the skill of wage earning, and that the wage is the benefit to the professional. Despite this, it appears that rulers do not benefit themselves as they do not earn wages, and this leads to the question of what makes the best men choose to rule. To this, he answers that the best men rule because it is better for them to accept such a position than to wait for the ruling position to be thrust upon them. Should they choose not to rule, they would have to be ruled by an inferior, and that is unacceptable. Thus, it is fear and necessity that forces them to rule for no benefit of their own. Despite this reasoning, the philosophers believe that they have not reached a conclusion, and so address the issue from a different standpoint.
Socrates starts again with Thrasymachus' view that perfect injustice is more profitable than perfect justice. Thrasymachus now defines justice as noble, good nature, and he defines injustice as good judgment. He then goes on to say that "a just man tries to get the better of his unlike, but not of his like; and unjust man tries to get the better of both."Book 1, pg. 24, line 349d However, through examination of other professions, such as medicine and music, and with Thrasymachus' agreement at each stage, Socrates proves that a just man is wise and good and an unjust man is bad and ignorant, which is contrary to what Thrasymachus asserted.
After some argument, Socrates asks Thrasymachus the same question again: "What sort of thing is justice compared with injustice?"Book 1, pg. 26, line 351 As an example, he questions whether an unjust city would enslave other cities and succeed in getting them under control. Thrasymachus answers this question by saying that that is exactly what such a city would do. Socrates then questions whether it is injustice or justice that a city needs to accomplish this. He begins by examining whether it needs injustice. In doing this, he concludes that in an unjust city everybody is unjust. Thus there will be disagreement in the city's army, and the soldiers will hate each other and be unable to ally against opponents. Furthermore, they will be unsettled inside themselves, since they are unjust, and they will also be enemies of the gods. On the other hand, just men have been shown to be wiser and more capable of acting together. However, there must be a little justice in unjust men, since they are not unjust towards each other: they can be 'partners in crime.'
The happiness of just men must be considered further, according to Socrates, since "it concerns the way we ought to live"Book 1, pg. 28, line 352d. First, through examples, he defines the function of a thing as something that can either be done only by it, or best by it. Also, he states that anything that has a function also has an excellence. If we combine these two assumptions, it can be assumed that everything performs its function only if it has the corresponding excellence and not evil. Using these hypotheses, he moves on to say that the soul has a function, life, which no other thing can perform. Furthermore, it cannot perform its function if it is deprived of its excellence, justice.
This means that a person with a bad soul will rule and manage badly, and one with a good soul will do these things well. Also, it means that the just man will live well, and the unjust man will live badly. Thus, the just man is happy, and the unjust man unhappy. This proves that injustice is never more profitable than justice, since it brings misery.
However, Socrates is disappointed, for although he knows that justice is wisdom and excellence, and is more profitable than injustice, he still doesn't know what justice is.