The Republic: Book I. What is justice?
Keep in mind as you read that in The Republic the concept of justice is closely associated with the concepts of right conduct or correct action, rather than a legal concept, such as to deal justice to offenders of the law, or legal retribution.
Cephalus - Cephalus is an old, wealthy man. He represents a general view of the conventional morality of ancient Greece. He regards the correct way to act (justice) is to pay one's debts to others and to tell the truth. He is not very interested in debating Socrates and formulating a specific view of Justice, rather he presents what actions many ancient greeks regarded as sufficient in order to get a good afterlife. Socrates presents him with a counter-example to Cephalus' view: the madman who asks for his weapon back. The counter-example is supposed to show that sometimes it is not just to return a weapon to a person if that person is going to cause harm to herself or others.
Polemarchus - Polemarchus is Cephalus' son. He takes over where Cephalus leaves off. Polemarchus amends Cephalus' view into one where justice is giving each what they are owed; then, in regards to Socrates' counter-example to Cephalus, he amends his view to be one where justice is benefiting one's friends and harming one's enemies.
Make sure to have The Republic at least up to Book V.
