I agree with Socrates that justice is good both for its own sake and for the sake of what comes from it.
I believe Glaucon's argument is based on the following claim:
If a person is motivated to perform an action, then that person must believe that performing that action is in her own self-interest.I believe that there are plentiful counterexamples, i.e., cases in which a person is motivated to perform an action, and yet the person does not believe that the action is in her self-interest. Doing what morality requires is often not in our self-interest, and yet those of us who are not sociopaths are strongly motivated to do what morality requires anyway. But most people I talk to can't seem to understand how it could be possible that a person is motivated to do something that is not in her self-interest. Why is that?
Here's a quick and rough speculation. Most people around here are Christians, and Christians are taught to believe that human beings are intrinsically and necessarily flawed creatures. No matter how virtuous we become, we will always be sinful. Sin is turning away from God, and God requires that we love our neighbor. Human beings are incapable of doing God's will perfectly, so even the most virtuous among us will succumb to what Kant called self-love when given a chance to help our fellow human beings. Christianity is so cynical about human nature that it holds that human beings must be bribed to be virtuous. But the promise of heaven merely appeals to self-interest. Christians are taught from the very beginning to wonder about any action, "What's in it for me?"
This might explain how the Republican Party succeeded in uniting certain libertarians and fundamentalist Christians. Because libertarian followers of Ayn Rand ask the very same question: "What's in it for me?" They have the same dreary view of human nature, but they worship it as the pinnacle of human virtue. For them, our only moral obligation is self-interest, and altruism is morally perverse. Since they share this view of human nature, it's not surprising that they are often allies.
This is one area in which atheism does better. An atheist does not do the right thing in the hope that she will be rewarded in the afterlife. Many atheists do the right thing because it is the right thing to do, and that's it. There's nothing really mysterious about this to me. It is actually unremarkable. I do not need to be bribed, and I do not need to be rewarded. The mere fact that it is morally wrong to perform a particular action is itself sufficient reason not to do it, and that's that.
P.S. Lesli, I'm disappointed that I can't read your blog anymore. Can we make some kind of arrangement? If the character of your blog has changed and we cannot, that's all right. Please let me know. Thank you.