We discussed Book I in order to put the work into context. Plato was worried that a failure to reflect on questions about justice left his society open to ideas like those that Thrasymachus articulated. Some might find Thrasymachus’s immoralism attractive. Others might avoid the political life if they were convinced that it was dominated by those who thought like Thrasymachus.
We then took up some questions about Glaucon’s challenge. The Republic seeks to answer the question that Glaucon poses. We were especially concerned with the connection between Glaucon’s account of justice and that of Thrasymachus, what it means to value something “for its own sake,” and the strength of the tests that Glaucon proposed.
Plato made a few assumptions about justice that will strike us as unusual. They’re recognizable points, but not familiar.
One of these is the assumption that justice is a skill. This is why the analogies with medicine, carpentry, and navigation in Book I are so prominent. We think of justice as involving rules that specify rights and obligations.
Another assumption is that we can give determinate answers to questions about how to live or what the best life is. I don’t mean to say that he thought there was a fairly specific way that it was best for all people to live. I do mean to say that he thought there were fairly specific things to say about what the best life for anyone would involve. The question about the value of justice is a question about whether being just is among those things that make up a good life.
We are more reluctant to think that there are many determinate things to say about what makes up the best life. We’re pretty sure about the things one needs to have a life with any value at all. But we’re reluctant to say that there is such a thing as a best life much less that we can say what it involves.
Finally, we’re inclined to think of justice and morality as having a special value, independent of other values and, at least potentially, in conflict with them. It’s fairly obvious how this view could arise for us. We’re heavily influenced by the idea that our moral code is the product of a divine law. This is not what Plato thought. Whatever valuing justice “for its own sake” means, it cannot mean thinking that its value is independent of other values. Rather, the thought is that justice is valuable only if it can be shown to be a part of the best life. If it conflicts with the best life, then Thrasymachus will have won, by Plato’s lights.