Plato and Aristotle treated morality as a genre of interpretation. They tried to show the true character of each of the main moral and political virtues (such as honor, civic responsibility, and justice), first by relating each to the others, and then to the broad ethical ideals their translators summarize as personal “happiness.” Here I use the terms “ethical” and “moral” in what might seem a special way. Moral standards prescribe how we ought to treat others; ethical standards, how we ought to live ourselves. The happiness that Plato and Aristotle evoked was to be achieved by living ethically; and this meant living according to independent moral principles.
We can—many people do—use either “ethical” or “moral” or both in a broader sense that erases this distinction, so that morality includes what I call ethics, and vice versa. But we would then have to recognize the distinction I draw in some other form in order to ask whether our ethical desire to lead good lives for ourselves provides a justifying moral reason for our concern with what we owe to others. Any of these different forms of expression would allow us to pursue the interesting idea that moral principles should be interpreted so that being moral makes us happy in the sense Plato and Aristotle meant.
In my book Justice for Hedgehogs—from which this essay is adapted—I try to pursue that interpretive project. We aim to find some ethical standard—some conception of what it is to live well—that will guide us in our interpretation of moral concepts. But there is an apparent obstacle. This strategy seems to suppose that we should understand our moral responsibilities in whatever way is best for us, but that goal seems contrary to the spirit of morality, because morality should not depend on any benefit that being moral might bring. We might try to meet this objection through a familiar philosophical distinction: we might distinguish between the content of moral principles, which must be categorical, and the justification of those principles, which might consistently appeal to the long-term interests of people bound by those principles.