When Cephalus departs to attend to the sacrifices, Polemarchus becomes the “heir of the argument”, as the rightful heir to Cephalus’s substance, and he defends Simonides’s interpretation of justice -that it is just to give to each what is owed. Like Cephalus, Polemarchus sees justice as something distributive. However, the implication in Polemarchus’s opinion, as with Cephalus’s, is that justice is good, not merely for the giver but also the receiver. Justice must be, therefore, a good thing in practice. But in some cases men make bad decisions with things that are owed to them, and most make bad decisions with their private property. Socrates returns to the question of the man with an unsound mind and the weapons that are owed to him. Ultimately, if we are to follow this line of thinking, which assumes that justice is good for both the giver and the receiver, then we might be tempted to abolish private property, for the owing of debts can lead people to do very bad things. In other words not all debts paid to other people are good. But there are very few people, if any, would be able to determine what kinds of things and what amounts of things, like private property, will be good for people. This would require a most high knowledge of things and would be the most extreme abstraction from the question of justice at hand.
While the first opinion of justice was only implied by Cephalus, and stated by Socrates, the second opinion of justice is wholly stated by Polemarchus with help from Socrates, and under the authority of the poets, namely Simonides. In essence, Polemarchus returns to Cephalus’s original claim and qualifies it such that justice is doing good to one’s friends and harm to one’s enemies -appropriately stated by the warlord. It is the only opinion of justice, of the three opinions stated in Book I, which is bookended by Socrates praising the poets as “wise men”. The opinion of Polemarchus presupposes some things that are neither just nor unjust -for example every human being is born with friends, his or her parents, and thereby also with enemies, the enemies of his or her family. To be human is to have friends and enemies. If justice is giving to one’s friends what is owed to them, the just man must have knowledge of a very high order to be able to clearly distinguish his friends from his enemies, and also what will be good for them, not unlike a physician.
To Polemarchus, justice is an art -the art of war. It is useful in the making of contracts. It is an art that presupposes men work together for the mutually beneficial destruction of their enemies. By introducing the art of war, and thereby of men working together, we must ask to what end the just group is striving? Up until this point the question of justice was an inquiry into the just man in his individual dealings with friends and enemies. However, now we understand that the opinion of justice implicitly includes the body politic, or the polis as its aim. To Polemarchus, this dedication is patriotism in public-spiritedness to one’s own city. In Polemarchus’s view, justice is full dedication to the common good, with nothing withheld from the city, and therefore it demands absolute communism.
While Cephalus’s opinion of justice was pious, entirely reliant upon the gods, Polemarchus’s view is amoral. The key to unraveling his opinion, is to distinguish between seeming friends and enemies -as human beings are prone err. The human being cannot possibly know everything about a good or a bad person. The ultimate conclusion leads us to believe that justice is helping one’s friends who are good and not harming anyone. Socrates concludes that he will join forces with Polemarchus against any poet who claims that justice is merely helping one’s friends who are good and not causing harm to anyone. In the third and final opinion of justice in Book I of The Republic, we encounter the bombastic rhetorician, Thrasymachus.