This discussion of psychology and moral development comes from Moore and Stewart's Moral Philosophy: A Comprehensive Introduction (Mayfield Publishing, 1994):

"Following in the footsteps of the French child psychologist Jean Piaget, whose book The Moral Judgement of the Child is considered the seminal work in its field, the late Lawrence Kohlberg attempted to establish the existence of a series of stages through which people pass as they develop their abilities to reason about morality. In his Essays on Moral Development, Kohlberg distinguishes three levels of moral development, each divided into two stages:

1. Preconventional:

a. punishment and obedience (avoid/submit)
b. egoism (satisfy one's own desires)

a. good/nice (please others)
b. uphold society (respect rules/authority)

3. Postconventional:

a. social contract (obey useful rules)
b. conscience and universal principles (autonomous assent to universal rules)

Kohlberg believes that these stages are common to all cultures and that to reach the highest stage -- something most of us do not manage -- we must pass through the earlier ones. The three levels characterize moral growth in terms of progress from a conception of right action as self-rewarding, to the view that right action is a matter of loyalty and conformity to social rules, and finally to the idea that right acts are those permitted by principles that are autonomously adopted.

Carol Gilligan, a former student of Kohlberg, has challenged his theory, noting that his use of male subjects may have resulted in a biased conclusion. Kohlberg claims, for instance, that fewer women than men reach the higher stage in his schema.In a Different Voice: Psychological Theory and Women's Development, Gilligan distinguishes two approaches to ethical thinking: (1) the justice perspective, according to which morality is understood primarily in terms of rules that specify rights and order them by relative importance when they conflict; and (2) the caring perspective, which emphasizes kindness and beneficence, maintaining personal relationships, and sensitivity to one's own needs and those of others in particular circumstances. She discusses Kohlberg's example of a man who can save the life of his wife only by stealing an expensive drug that he cannot afford to buy. One taking the justice perspective would likely justify the act on the basis of a right to life having priority over property rights, at least in this type of case. Someone who had the care perspective, in contrast, would focus on what could be done to sustain relationships and meet urgent needs of everyone, if that is possible. The conclusion might be the same, but the approaches are different -- especially regarding the centrality of general rule. Obligations and rights, in fact, might depend on a climate in which trust is normal and reasonable, as the philosopher Annette Baier has argued in her article "What Do Women Want in a Moral Theory?" The nurturing of relationships of trust might be a more fundamental moral concern than the imposition of obligations and the recognition of rights. Gilligan found that more women than men approach moral issues from the care perspective, perhaps because of innate differences, perhaps because of socialization. She summarizes the levels of moral growth from the care perspective thus:

1. Preconventional: self-centered (one's own needs are the sole focus of concern)
2. Conventional: self-sacrificing (the needs of others are of greater concern)
3. Postconventional: mature ethic of caring (can balance one's own needs and those of others)

Kohlberg admitted the significance of Gilligan's findings and modified his own theory in response; he came to see that the care perspective is an equally valid alternative. Gilligan similarly acknowledges the value of both perspectives in her recent work. Gilligan's research has given inspiration and direction to many women philosophers, particularly feminists, who are developing convincing alternatives to rationalistic, obligation-centered approaches to ethical theory often associated with a masculine perspective."