In Book IV of Plato’s Republic, Socrates and his interlocutors finally complete their creation of the ideal State. Because the perfect State possesses all virtues, Socrates resolves to identify the four primary virtues – wisdom, courage, temperance, and justice – within the State, and then draw an analogy between the just State and the just man.
Socrates first considers the virtue of wisdom. A wise State is “a State that knows best how to deal with itself and with other States.” The duty of the rulers is to determine what is best for the State. Thus, if the rulers possess wisdom, then the State will, too. Whether the soldiers and laborers are wise is irrelevant because soldiers and laborers do not legislate and enforce laws.
Having identified wisdom, Socrates turns his attention to the virtue of courage. He defines courage as the “true opinion about real and false dangers.” In other words, a man who knows what to fear – such as dishonor, shame, and defeat – and what not to fear – such as hardships, injury, and death – is courageous. Like the case of wisdom, a State is only courageous if one class of its citizens is courageous – the soldier class. Whether the rulers and laborers are courageous is irrelevant because the rulers and laborers do not fight in wars.
Socrates next examines the virtue of temperance. Temperance is “the agreement of the naturally superior and inferior, as to the right to rule.” To clarify, consider man, who is composed of a rational part and an irrational part. A man possesses temperance when his rational part controls his irrational desires. For example, a man who reasons that it is unwise to eat fast food everyday – and therefore eats healthy foods instead of junk foods – is temperate. On the other hand, a man whose desire for junk food overrules his understanding that such behavior is unhealthy is intemperate. Thus, in the State, temperance is the agreement between all citizens that the rulers ought to rule, and the other classes ought to be ruled.
Finally, the conversation arrives at the notion of justice. According to Socrates, justice, above all other virtues, “contributes most to the excellence of the State” and to the excellence of the individual. He defines justice in the State as every class performing its own role and not meddling in the affairs of the other classes. Thus, in a just State, the rulers rule, the soldiers fight, and the laborers produce. In an unjust State, laborers rebel and try to rule, rulers are forced to produce, and soldiers do not fight.
After defining justice within a State, Socrates applies this definition of justice to man. Recall that justice is every part of a whole fulfilling its assigned role and not meddling in the duties of the other parts. In order to determine whether a man’s parts are performing their proper roles, we must first identify the parts that comprise man. According to Socrates, man is composed of three parts – the rational and irrational parts that have already been discussed, and the spirited part, which is the passionate ally of the rational part.
There is an important distinction between the irrational part, which is desire, and the spirited part, which is passion. To illustrate this distinction, consider a man who is angry with himself for having eaten an entire cake. That anger is the response of the spirited part of man to the victory of the irrational part over the rational part. The more noble a man is, the more indignant he is whenever he suffers injustice. “When the noble man suffers unjustly, his indignation is his great support; hunger and thirst cannot tame him; the spirit within him must do or die, until the voice of the shepherd, that is, of reason, bidding his dog bark no more, is heard within. This shows that passion is the ally of reason.”
Thus, a just man is he whose three parts fulfill their proper roles. The rational part ought to rule over the other parts; the irrational part ought to yield to the command of the rational part; and the spirited part ought to lend support to the dictates of the rational part. A man can only suffer injustice when one of his parts transgresses the bounds of its role. When the spirited part does not lend support to the rational part’s commands, and the irrational part rules over the others, a man suffers injustice and becomes wicked. With these notions in mind, “the old question returns upon us: Is justice or injustice the more profitable? The question has now become ridiculous. For injustice, like mortal disease, makes life not worth having.”