Plato sets out to answer a question about individuals: why should
someone be just? But before he addresses that question, he starts on
what looks like a different one: what is justice in a city?
Plato’s assumption is that justice is the same for the city and for
the individual, such that a description of justice in the city would
help us to answer our original question about justice in the
So Plato is going to try to answer four questions.
What is a just city?
Why is it good for a city to be just?
What is a just person? (“individual” or “soul” are equivalent
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:
Justice in the city is the same as it is in the individual
Can he keep all five balls in the air? He comes surprisingly close!
Plato is awesome.
I will start by summarizing the readings from Books II and III. Then
I will say a bit about the selection and education of the guardians.
Finally, we will talk about the first part of Book IV.
What happens in Books II and III
Socrates begins by explaining why people form cities in the first
The most basic reason is that we aren’t self-sufficient; we need to
work with others to meet our needs. We do this through a division of
The kind of city that would be sufficient to meet our needs would be
quite simple. There would be a division of labor but its members would
only work to meet their needs. Glaucon describes this as a city fit for
pigs, without proper furniture, the arts, and so on. So they move on to
describe a second, luxurious city that would succeed it.
They didn’t find justice in the first city; if they had, that would
be the end of the book. So you would expect the second city to be a step
forward. But that does not seem to be Plato’s attitude. He seems to
regard it as a step backwards. He calls the city of pigs
“healthy” and its successor, where they will find justice, “fevered”
(373a). I have to confess that I do not understand what he thinks about
the first city, that is, the city of pigs. Is it bad or good? The rest
of the argument does not depend on answering that, as far as I can see.
So the fact that I don’t know the answer isn’t a big deal. But it bugs
Moving along to the luxurious city, we find that it brings conflict,
and hence the need for what Plato calls “guardians” to defend the city
against outsiders who will want to take its goods.
But a class of guardians who are strong enough to defend the city
from outsiders will also be capable of exploiting the insiders. We
formed a city to benefit from a division of labor but that would be a
bad deal if it meant being enslaved by the army. Is the situation
hopeless? Plato thinks not. Guard dogs are ferocious towards outsiders
but not their owners. Why? They are selected and trained to behave that
way. Couldn’t we do something similar for guardians? Could a program of
selection and training produce people who will defend the city from
outsiders without taking advantage of the insiders?
Plato thinks the answer is yes and he describes how the selection and
training of the guardians should go. You will find a lot of what he says
rather eccentric. There is a lot of emphasis on music and poetry, for
instance. It’s not a modern educational program.
I’m going to ask you to put the details to one side and consider the
basic idea. That idea is that a society should put a lot of effort into
identifying and training its leaders. You can have leaders who have been
trained to be good at the job. Or you can have leaders who are good at
being elected, as in a democracy. Or you can have leaders who are or
good at picking their parents, as in a monarchy. Which system makes the
most sense? It’s not a bad question.
Where we are headed
This is what Plato is aiming at. There are three parts in the city
and there are three corresponding parts of the soul.
Part of the City
Part of the Soul
The guardians are the rulers. The auxiliaries are the security force;
they are potential guardians who didn’t make the cut. The productive
class is everyone else, that is, the people who make and sell goods and
services. We’ll get to the soul next time.
Justice consists in each one of these parts sticking to its role and
not interfering with the others. Here is what he says about the
the city was thought to be just when each of the three natural
classes within it did its own work. (435b)
the principle that it is right for someone who is by nature a cobbler
to practice cobblery and nothing else, for the carpenter to practice
carpentry, and the same for the others is a sort of image of justice —
that’s why it’s beneficial. (443c)
You can see why this would be a good thing. Everyone is doing what
they do best. You can’t get better than best! It’s less clear why you
would call it justice.
A split among the virtues in Book IV
Virtues are good qualities. Vices, by contrast, are bad ones.
Plato says a good city would have four virtues: wisdom, courage,
moderation, and justice. Why only four? Got me.
The city has the first two virtues, wisdom and courage, 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 is 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.
The third and fourth virtues, moderation and justice, are different.
The city is moderate and just because, in some sense, everyone
in it is moderate and just.1
Wisdom and courage 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. Justice and moderation follow what I called the
part-whole rule: the whole city has virtue V because all of its
parts (the individual members) of the city have virtue V.
We talked a lot about a significant problem with the Republic: why
would the guardians want to rule? The guardians are supposed to love
knowledge above all else. But it is notoriously difficult to run a city
while also engaging in intellectual pursuits. As Hannah and Colin asked:
why would they do it?
One possible answer is that their studies will lead them to
understand why that is something they should do. Plato holds out hope
Another possible answer is that they fear the alternative of rule by
someone who is far worse.
Jack had an interesting point that there is tension between their
thinking of themselves as an elite that is separate from the rest and
their being devoted to making everyone’s lives better. Why would they
care about people who they think of as inferior to themselves? How is
that supposed to work? It’s a good question.
These are the things you should know.
What are the parts of the city called?
What are the parts of the soul called?
What is the difference between wisdom and courage, on the one
hand, and moderation and justice, on the other hand, as virtues of the
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.
If you are unsure of what the difference between
moderation and justice is, you’re in good company. I can’t figure it out
either. They are, at least, very close. Fortunately, nothing much turns
on our ability to separate them so we can let it go.↩︎