In The Republic, four definitions of justice are given by the four characters Cephalus, Polemarchus, Thrasymachus, and Glaucon.
First, Cephalus explains that justice consists in following the laws and repaying one’s creditors. Socrates points out that repaying one’s creditors is not always a good idea. For example, if one borrows a weapon from a man who has gone mad, it would not seem right to return the weapon to him. In other words, although the man is indeed the owner of that weapon, now that he is mad he may use it unjustly and harm others. Therefore, this cannot be a good definition of justice.
Second, Polemarchus, Cephalus’ son, defines justice as helping friends and harming enemies. Socrates, again, says that this cannot be right because men often make mistakes in judging who the real friends are and who the enemies are. And it might occur that one erroneously harm a friend and help and enemy.
Third, the Sophist Thrasymachus, espouses the view that “might is right.” He argues that such terms as “justice” and “right” are relative. What benefits the stronger party is just. The stronger, thus, decides what justice is. Socrates is not convinced; in fact, he says that rulers can make mistakes and unintentionally enact laws that do not benefit themselves, but rather their subjects. Thus, in that case, the stronger would not benefit from being unjust, while the weaker would, and this is inconsistent with Thrasymachus’ argument. Furthermore, Socrates continues, justice cannot refer to the acts of a crafty despot. Even a group of criminals would not be successful if they were not just to one another.
Fourth, Glaucon says that “[justice] is always practiced with reluctance, not as good in itself, but as a thing one cannot do without” (43). To further show his idea, he tells the legend of Gyges, who finds a ring that gives him the power to become invisible. Gyges is able to seduce a queen, murder the king, and take over the kingdom using his magic ring knowing that he will avoid being punished. Glaucon uses this analogy to conclude the sole reason men are just is that they fear punishment.
Thus, in books 2-4 of the Republic, Glaucon and Adeimantus challenge Socrates to show that justice is always preferable to injustice. Namely, Socrates is asked to prove that justice is intrinsically good as opposed to being only instrumentally good. But what does all that mean? According to Glaucon, there are three types of goods:
1. Intrinsic good: anything that is valuable for its own sake is said to be intrinsically good. For example, the pleasure generated by reading a book, sexual pleasure, and indeed any type of enjoyment, are pursued for their own sake and not because they lead to something else as for example wealth, which is a useful good in the sense that it allows a person to buy whatever that person wants.
2) Instrumental good: unlike good for its own sake, instrumental good is something that is desirable for the good generated by it. Wealth, for example, as we noted, is not good in itself; in fact, if you are stranded on a desert island, you may possess a million dollars, but it won’t be any good to you. However, if you live in a society, wealth is a good instrument with which you can buy your personal island and be happy. There is also a type of instrumental good that is not desirable although it can generate good, and that is pain. Think about the pain one endures at the dentist’s. No one would choose to have one’s tooth drilled by a dentist for its own sake, but rather for the sake of having healthy teeth.
3) Intrinsic/Instrumental: the combination of both intrinsic and instrumental is the third type of good. For example, health is not only desirable for its own sake, but also because it allows one who is healthy to study, work, have sex, make money, buy an island, and so on. In other words, health is intrinsically good because being healthy is valuable for its own sake, as well as being instrumentally good because of the good it can generate.
Now, Glaucon explains, it appears that justice is a type of good like pain: justice is at best instrumentally good, but certainly not desirable for its own sake—and in fact people are reluctantly just. People practice justice for two reasons: 1) justice is convenient—one is just because he wants to be treated justly in return, and 2) justice is compulsory—one is just because he fears that not being just can lead to punishment. And to emphasize his point, Glaucon tells the story of Gyges. Gyges was a shepherd who found a magic ring that rendered invisible the person who wore it. Gyges took advantage of the ring’s magic property and used it to seduce a queen, murder a king, and take the king’s place unpunished. The moral of the story is that if, like Gyges, people had the opportunity to be unjust without being caught and punished, there seems to be no reason why anyone would prefer justice over injustice.
To defend justice and show its intrinsic value, Socrates conducts a philosophical investigation into the foundation of an ideal city. He proposes that if a city is correctly set up, justice will be found in it; and with the help of Glaucon and Adeimantus, Socrates will be able to identify it. “But why does Socrates wish to investigate justice in a city?” one may ask. The answer is two-fold: first, if there is a justice that belongs to an individual and a justice that belongs to a city, it will be much easier to see justice on a larger scale; thus, we first try to find justice in a city. Second, individuals are not self-sufficient. Human beings have similar goals, i.e., food, shelter, clothing; in order to achieve these goals more efficiently, people gathers together into communities where each individual specializes in a specific craft: I make shoes and she grows vegetables, etc. To be sure, the separation of specializations is the key factor to the establishment of a just society.
The first building blocks of the ideal society are shoemakers, tailors, and all types of craftsmen. And if people desire to have luxuries and live comfortably, a city also needs merchants to sell and buy goods, wine makers, farmers, and so on. A prosperous city, it occurs to Socrates, needs a body of soldiers-rulers who will protect the city from possible invasions. These soldiers are called “guardians.” Guardians must be physically strong individuals, and mentally gifted, as well; and they are chosen for their intellectual and physical abilities rather than for their social class. The less gifted individuals will be soldiers called “auxiliaries,” and the even less gifted will be the rest of the citizens, including craftsmen, farmers, and so on.
With regard to their preparation, guardians will undergo intense physical training as well as philosophical and musical training, and other subjects that enrich their soul and create an internal harmony between the mind, and the body. To keep the guardians away from any source of corruption and ensure total dedication to the commonwealth, Socrates suggests the abolishment of riches among them, and even the abolishment of certain literature that, for example, deals with heroes defying the laws or disrespecting the gods. The purpose of such a meticulous and intensive training is to select and educate individuals who will naturally choose to dedicate their lives to the well-being of the city over the pursuit of materialistic values.
A well-organized body of rulers, auxiliaries, merchants, craftsmen, and the rest of the citizens are all the elements required to the establishment of the ideal city. And at this point, it is time to look into it to find justice. The way Socrates investigates to find justice is to look for specific attributes that a virtuous city must possess; namely, an ideal city must be wise, courageous, temperate, and just.
Wisdom is easy to find, Socrates notes. In fact, if we have successfully trained such dedicated and wise guardians, who know how to rule the city, these guardians must possess the virtue of wisdom. The second virtue is courage. Socrates argues that a courageous city is shown by the dedication of its soldiers, the auxiliaries. These soldiers, through the education they have received, have the power to preserve the belief in what they should fear, namely, the loss of their integrity, which is their dedication to protecting the city at any cost. The third virtue is temperance. Temperance is indicated by the harmony among all the different classes in the city, i.e., guardians, auxiliaries, craftsmen, and the rest of the citizens. Every member of each class maintains his or her social place and doesn’t desire to become a member of a different class. That is to say, if a city has temperance, a craftsman would never wish to be a ruler because being a craftsman represents the highest achievement of his potentials, just as a guardian would never desire another position than being a guardian. Another way to put it is that a temperate city is one whose citizens are happy to be who they are because they achieve their vocations according to their nature, and therefore will never wish to be something else.
Having found wisdom in the guardians, courage in the auxiliaries, and temperance in the fact that none of the individuals in either group desires to belong to a group other than his own, Socrates needs to find where justice lies in the city. Then suddenly, it occurs to Socrates that justice in a city thus constructed must be what keeps its various groups separated and at the same time makes all the groups work in perfect harmony, just as in music when a series of distinctive notes make up a beautiful melody.
To complete his investigation, Socrates now has to find justice in the individual. He argues that in order to accomplish this task, he has to take the same approach used to find justice in the city. Therefore, he looks into the individual to find wisdom, courage, temperance, and justice. Justice will be what keeps the parts of one’s soul separated, each doing its own proper work. Socrates shows that one’s soul has these three parts by analyzing inner conflict. Wisdom in the individual, according to Socrates, is what steers a man in the right direction when he experiences an inner conflict. In every individual there are two elements, one responsible for physical appetites, and the other is a rational element that often allows one to refrain from certain appetites. Take for instance a married man who has an opportunity to commit adultery, but decides not to. What occurs is that the appetitive element in his soul impels him to have sex with the woman, but the rational element stops him from having extramarital sex. However, sometimes the appetitive element prevails over the rational element; and as in this case, the man decides to have extramarital sex. But there is in the soul a third element, which Socrates calls “spirit.” A person’s spirit works like this: to take the same example, the man’s appetite steers him in the wrong direction, i.e. to have extramarital sex; but the man’ spirit in the form of anger allies with the rational element to fight against the appetite.
The foregoing parts in the individual’s soul (reason, appetite, spirit) mirror the virtues possessed by the guardians, the auxiliaries, and the citizens in the city: an individual’s wisdom, as noted, is the rational element in his soul that refrains an individual from certain appetites; this is paralleled with the wisdom possessed by the guardians who should rule over the appetites of the citizens. Spirit in the individual preserves the power exerted by an individual’s rational element through different obstacles, and allows him to safeguard his integrity; this mirror courage in the city, which is shown by the auxiliaries who have the power to preserve the belief in what they should fear, namely, the loss of their integrity; and temperance in the individual is when each of these parts in the soul performs its own duty appropriately and does not try to take over the function of any other parts, i.e., appetites do not try to rule over reason; similarly, in the city, temperance is indicated by the harmony among all the different classes, guardians, auxiliaries, craftsmen, and the rest of the citizens, when every member of each class maintains his or her social place and doesn’t desire to become a member of a different class. Thus, when reason, spirit, and appetite agree that reason alone should rule over the soul, there is justice within the individual. Equivalently, when the guardians, auxiliaries, and the citizens agree that the guardians alone should make decisions for the entire city, justice in the city is present.
Now let us imagine a city where a shoemaker rules, and a guardian makes shoes, and a soldier cultivates vegetables. Could this be a good and just state? Obviously it couldn’t. Ideally, each class should do its own work and not meddle with another’s. Likewise, could an individual whose appetites prevail over reason be at peace with himself? The answer is again no.
Justice in the individual, then, is an internal order of the soul among the different parts. When in fact the parts in the soul do their respective work, Socrates suggests, justice is produced as in a healthy body, whose organs function properly. Injustice, it follows, is the opposite, that is, a state of internal discord. At this point, it is clear that justice must be the highest good—which is desirable for its own good and the good it can generate.