For many people, the reason why we should be moral is that it benefits us to do so. But what if we would benefit more from being immoral? That is the question raised in Plato's story about the ring of Gyges. In response to this challenge, Socrates and Plato argue that people are immoral only because they think that immorality is in their own self-interest. But, in fact, it is a mistake to think this: no one who is immoral can truly be happy, because being virtuous means having a balanced or healthy personality--that is, a personality that is able to make clear-headed judgments and to act on them freely and courageously.
For Plato, psychological health and moral rectitude are achieved when the three parts of the soul are in harmony. That is, individual happiness occurs when the ruling part (reason) knows what we need to do to exist harmoniously with other people, the enforcing part (spirit, drive, emotion, commitment) is the courage to act on ethical principles; and the sensual part (appetites, lusts, and irrational desires) provides the power to get things done. Justice is acting in accord with what reason dictates we ought to do (given our place in society): this is one's aret‚ or virtue. Human excellence is possible only when such a balance of the parts of the self is achieved. We should thus be moral because not to do so is to choose not to be harmoniously integrated with oneself.
For Socrates, virtue is the strength of character that guarantees one's happiness. Immoral acts undermine our character insofar as they weaken our future ability to act freely and courageously. Immorality thus hurts us by weakening our ability to discern the good, to control our passions, and to do what we know is right. The constant need to satisfy unfulfillable desires robs us of our freedom, compelling us (often unconsciously) toward an endless search for more and different pleasures.
II. Critics of this view (e.g., Callicles in Plato's Gorgias, or more recently Friedrich Nietzsche) claim that self-restraint and moderation are virtues only to those who are unable to affirm their natural abilities to create values. According to Nietzsche, morality is a means by which those who are weak or unwilling to propose new standards for human progress try to restrain those who want to advance beyond the "all too human" values of the common, ordinary masses of people. Nietzsche points out how individuals who appeal to ethical principles and who claim to defend the rights of all people (especially the weak) are themselves the embodiment of the very will to create standards that they find so threatening in those who value power over self-control.
For Nietzsche, thinkers like Socrates seem not to notice how their recommendations of morality are themselves expressions of power, and they do not acknowledge their own tendency toward domination. So those who say that we should be moral because we cannot otherwise be happy do not understand that the constant challenge of creating new values can produce as much happiness (if not more) as the contentment of doing that which people in general might view as reasonable. It is mistake to think that all "immoral" acts are indications of a weak will or a perverted ability to reason. The acts of powerful, superior individuals--those who propose advancing the standards by which human beings identify values--will certainly be understood by lesser people as immoral. But those lesser individuals do not recognize how a moral system (e.g., Christianity) which defines virtue in terms of self-restraint and equal treatment of all people (including even the weak) is itself also an example of the will to dominate and control.