Political Philosophy Spring 2019

Glaucon’s Challenge


Plato’s goal in the Republic is to answer Glaucon’s challenge. The challenge appears to be straightforward. Socrates has to show that justice falls into the category of things that are valued both for their own sakes and also for what comes from them.

Glaucon himself makes the case for thinking that justice belongs to a different category of things, namely, the ones that are valued only for what comes from them. Being just is like taking medicine or engaging in unpleasant physical training: if you could get the results you wanted without it, you would not do it (357).

I asked two questions about Glaucon’s challenge.

  1. Why do the participants in the dialogue all agree that what Glaucon and Thrasymachus are basically saying the same thing?

  2. How does Glaucon characterize an unjust person?

Thrasymachus and Glaucon

Thrasymachus portrays justice as a fraud. It either functions to enable the strong to exploit the weak or it is something that is venerated by the weak and foolish and ignored by the strong and clever.1

Glaucon, by contrast, describes justice as a reasonable looking deal. People found it impossible to get along without rules, so they made some rules, and that’s what we call justice.

Those two stories look quite different to me. But Plato treats them as being the same thing. Why?

Bex said that they both emphasize appearances. For each thinker, the wise person will see through the way things are generally taken to be and, when appropriate, act deceptively to get ahead.

Chloe added that they both agree that following the rules of justice is a means to an end rather than an end in itself. They both think the only reason to be just is that it will get you some other benefit. Being just is not a goal that anyone aims for on its own. So when it isn’t beneficial to be just, there is no reason to do it.

That said, I still think there is an important difference between Glaucon and Thrasymachus. Suppose you came to this book as a basically good person. If you were convinced by Thrasymachus, you should be convinced that you were mistaken and what you thought was a basically good life actually doesn’t make any sense. If you were convinced by Glaucon, you would also conclude that you were mistaken about what justice is really like. But I don’t see how coming to that conclusion would obviously lead you to reject justice altogether. You can still see the rules as good and worthy of your compliance even if they aren’t the way you thought they were.

Plato doesn’t see it that way, of course. But this is a point on which I think I disagree with him.

What is an unjust person like?

I said that Glaucon characterized the unjust person in two different ways.

  1. As someone who is exclusively concerned with outdoing others and always acquiring more of anything (359c). Here the unjust person is competitive or greedy (or both).

  2. As someone who is indifferent towards the rules of justice in pursuing his or her aims (362b-c). Here the unjust person is amoral but not necessarily competitive or greedy.

At the end of the book, Plato is going to argue that the life of the first kind of person is miserable. I can see the point. That person’s life is governed by what others do or by a mindless drive to acquire things. He will make a good case for thinking that this kind of life is empty and out of control.

However I am not convinced that Plato ever comes to grips with the second way of being unjust. Since that kind of unjust life seems much more attractive to me, I think it’s the one to beat. But I also think it’s left standing at the end of the book.

Main ideas

  1. What is Glaucon’s challenge?
  2. How is it related to Thrasymachus’s attacks on justice?
  3. What is an unjust person like, according to Glaucon?


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.

  1. I say it is either one of those things because Thrasymachus is unclear about exactly what he thinks. More generally, you could see Thrasymachus as being genuinely outraged on behalf of the people who are exploited by the strong. Or you could see him as sardonically celebrating the way the strong flout the rules. It is probably most accurate to say that he is driven more by hatred for the existing order more than being on the side of either the weak or the strong.↩︎