INTRODUCTION

Some two thousand three hundred years ago, Plato presented us a classic formulation of an ethical problem that has disconcerted thinkers about morality ever since. In his book The Republic, Plato has Glaucon tell the story of a young shepherd, Gyges, who discovers a ring that enables him to become invisible at will. With the special powers the ring gives him, Gyges proceeds to seduce the queen of his city, murder the king, and seize the throne. Glaucon intends his little parable to point a lesson about human nature. All of us, he suggests, behave morally only because, unlike Gyges, we know that immoral behavior usually will be detected and punished. “There is no one,” he says, “who would have such iron strength of will as to stick to what is right and keep his hands off other people's property. For he would be able to steal from the shops whatever he wanted without fear of detection, to go into any man's house and seduce his wife, to murder or release from prison anyone he felt inclined” (Plato 1955, p. 91).

What Plato has illustrated for us in this story is the ethical problem of egoism: Why, if we can get away with it, shouldn't we pursue our own selfinterest at the expense of any, or even all, other people? Why should we ever behave altruistically, that is, act so as to bring about the good of others, except when we have to do so to get them to help us further our own good?