Plato’s Republic is a Socratic dialogue written by the philosopher Plato in 360 B.C.E. The main character Socrates and other Athenians discuss the meaning of justice and try to examine whether the just man is happier than the unjust man. In order to do this, they imagine a city ruled by philosopher kings and guardians. The main theme in The Republic is of course justice, and in the first book the character of Glaucon presents Socrates with a challenge in their search for the meaning of justice.
Gluacon, after hearing Thrasymacus praise injustice, wants to challenge Socrates to defend the just life in the way that he wants. Glaucon wants it to be praised just in itself and believes he will get this from Socrates by hearing him denounce justice and praise justice. Glaucon takes up Thrasymachus’ argument, that the unjust life is better than the just life and challenges Socrates to prove that just life is better. He separates ‘good’ into three classes. The first is intrinsic goods such as happiness which we like because of its own sake. The second is the kind of good that is liked not just for its own sake but also because of its consequences, like knowledge, and the third type is intrinsic good that is only wanted for its consequences. Glaucon challenges Socrates to place the just life in one of these classes. Socrates says it belongs in the second, because a just life is liked for own sake and the consequences it brings. Glaucon however believes it belongs in the third class because the just life is only desired for its consequences. He says, “The best is to do injustice without paying the penalty; the worst is to suffer it without being able to take revenge. Justice is a mean between these two extremes.”
Glaucon and Socrates think they have found the meaning of justice and injustice in the city. They realize that their first goal was to find the meanings in an individual and now that they have a grasp on it in a larger scale, they turn to the individual. However...