Political Philosophy Fall 2019

Justice in the City


We set out to answer a question about individual people: why should someone be just? But before he addresses that question, Plato asks what appears to be a different one: what is justice in a city?

Plato’s assumption is that justice is the same in the city and the individual soul, such that a description of justice in the city would help us to answer our original question about justice in the individual.

So Plato is going to try to answer four questions.

  1. What is a just city?
  2. Why is it good for a city to be just?
  3. What is a just person? (“individual” or “soul” are equivalent terms)
  4. Why is it good for a person to be just?

And he is going to try to answer these questions while also maintaining this assumption:

  1. Justice in the city is the same as it is in the individual soul.

Can he keep all five balls in the air? He comes surprisingly close! Plato is awesome.

In today’s class, I summarized the readings from Books II and III and said a bit about the selection and education of the guardians. Then we discussed the first part of Book IV.

A split among the virtues

The good city would have the four virtues of wisdom, courage, moderation, and justice. It has the first two virtues because of the roles played by the different classes. For instance, the city is wise because it is ruled by the class that knows the most about what is good and is the most dedicated to the city: the guardians. And it is courageous because the auxiliaries are in charge of their defense.

Note that the city is not courageous because everyone is courageous; it’s only the auxiliaries who have to be courageous (see 429b). Nor is the city wise because everyone is wise (428e). The city has these qualities because a particular class plays its role: the guardians run the city and the auxiliaries defend it. These virtues follow what I called the predominant part rule: the city has virtue V because the relevant predominant part of the city has the virtue V.

Moderation and justice are different. The city is moderate and just because, in some sense, everyone in it is moderate and just. These virtues follow what I called the part-whole rule: they whole city has virtue V because all of its parts (the individual members) of the city have virtue V.

Keep this in mind for next time. I think Plato is going to have a hard time explaining how moderation and justice work.

Main points

These are the things you should know.

  1. What are the parts of the city called?
  2. What are the parts of the soul called?
  3. What is the difference between wisdom and courage, on the one hand, and moderation and justice, on the other hand, as virtues of the city?


Plato. 1997. “Republic.” In Complete Works, edited by John M. Cooper, translated by G. M. A. Grube and C. D. C Reeve. Indianapolis, IN: Hackett Publishing Company.


There was a handout for this class: 03.PlatoModerationJustice.handout.pdf