Political Philosophy Fall 2021

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 want to discuss two questions about Glaucon’s challenge.

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

  2. How does Glaucon characterize an unjust person?

Thrasymachus and Glaucon

Thrasymachus is a bit of a mess. Sometimes he says that justice is something that the strong impose on the weak; that is what he means when he calls justice the advantage of the stronger. Other times he says that justice is a constraint that the strong ignore; that is what he means when he calls justice another’s advantage. He never really puts it all together to give a clear statement of what he believes.

Even worse, Socrates’s refutations of Thrasymachus are not much better. At best, they are more clever than convincing. Thrasymachus gives up but only because he is outmatched. Neither he nor the reader understands why Socrates is right.

For our purposes, none of this matters. We aren’t going to try to figure out exactly what Thrasymachus is saying or exactly how Socrates’s arguments work. The figure we care about the most is Glaucon. So if you are feeling overwhelmed in the second half of Book I that is both normal and not really a problem. You just need to get a feel the kind of thing that Thrasymachus is saying. Don’t sweat the details.

One thing we do care about is how Glaucon’s position is like Thrasymachus’s. Here is how I see it.

Thrasymachus portrays justice as a fraud. It is either imposed by the strong on the weak or it is a constraint that the weak respect that the strong ignore.

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?

Our discussion

In our discussion, Jayden said that the reason why all the characters see Glaucon and Thrasymachus as saying basically the same thing is that they are both saying that it makes sense to ignore the rules if you can get away with it. The concern, in other words, is with people who discover that they have the power to ignore the rules. Imagine someone gains control of the state, for instance, and does not face any check on his power. Why should such a person behave ethically?

I think that is right in two ways. First, this is probably what Plato had in mind. Second, it is certainly a question worth answering.

At the same time, there are other respects in which Thrasymachus and Glaucon are saying quite different things. This matters. Suppose Plato does not succeed in showing that it is supremely rational to be just even if you could get away with being unjust. It would make a difference whether justice is as Thrasymachus describes it or if it is more like Glaucon says it is. It’s the difference between being exploited and striking a reasonable deal.

In addition, Kari raised an excellent question: why do they make the consequences of justice and injustice negative and positive, respectively? Why not make the consequences the same?

Let me explain. In order to answer Glaucon’s challenge, Socrates has to show that justice is desirable for its own sake as well as for what comes from being just. They agree that “what comes” from being just mostly depends on the effects of having a good or bad reputation. If you are just, others will trust you and if you are unjust they won’t; the advantages of being trusted are obvious. They all agree that the appropriate test is to imagine that the just person will have the reputation of an unjust person while the unjust person will have the reputation of a just person. People will trust the unjust person and distrust the just one. Socrates will have to show that the just person’s life is superior to the unjust person’s life with their reputations reversed like that.

Kari asked why the two lives were not imagined to have the same kind of reputation. We are trying to find out what is good about justice, or bad about injustice, apart from the effects of being just or unjust. If you make the reputations the same, you set “what comes” from being just or unjust as equal; that enables you to compare justice with injustice apart from their effects. If Kari is right, they are setting the bar way too high. The way Plato has set it up, Socrates has to show that it’s better to be just even if the consequences of being just are far, far worse than the consequences of being unjust.

Chloe responded that Plato chose this comparison because it involves the purest just and unjust lives: someone who persists in doing the right thing even though she gets no credit for it and someone who is so dishonest that he succeeds in fooling everyone about how corrupt he is. I think she’s right about Plato’s thinking and you can see how this test is related to Jayden’s point above: we’re trying to say something about the person who can get away with it.

That said, passing this test does not appear to be necessary to show that justice belongs in Glaucon’s second category of goods: those things that are desired for themselves and for “what comes” from them. If Socrates could show that justice is valuable even the just person’s reputation is the same as an unjust person’s, that would be enough to show that justice belongs in the second category.

What is an unjust person like?

I’m going to give away the end of the story here.

Glaucon characterizes the unjust person in two different ways.

  1. As someone who is exclusively concerned with outdoing others and always acquiring more of anything (359c). On this way of understanding injustice, unjust people are 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, unjust people are amoral concerning the means they use to achieve their ends but their ends are 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. 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. At least, I am persuaded.

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

These are things you should feel have an opinion about by the end of class.

  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.