Lawrence Kohlberg, an educational psychologist, has traced what he believes to be six sequential stages of ethical reasoning through which each person progresses as part of his normal mental development. The child moves from an unquestioning dependence on external rules and controls to an increasingly sophisticated set of internalized standards, as follows: (1) simple obedience to rules and authority; (2) conformity to group behavior to obtain rewards and exchange favors; (3) good-boy orientation, conformity to avoid dislike and rejection by others; (4) duty orientation, conformity to avoid censure by authority, disruption of order, and resulting guilt, (5) legalistic orientation, recognition of the value of contracts, some arbitrariness in rule formation to maintain the common good, (6) conscience or principle orientation, primary allegiance to principles of choice, which can overrule law in cases the law is judged to do more harm than good.
The stages were based on children’s verbal respnses, as elicited by questions about moral problems. Depending on intelligence and training, individuals can stop at any rung on the ladder. Most attain stages four or five. By stage four they are at approximately the level of morality reached by baboon and chimpanzee troops. At stage five, when the ethical reference becomes partly contractual and legalistic, they incorporate the morality on which I believe most of human social evolution has been based. To the extent that this interpretation is correct, the ontogeny of moral development is likely to have been genetically assimilated and is now part of the automatically guided process of mental development. Individuals are steered by learning rules and relatively inflexible emotional responses to progress through stage five. Some are diverted by extraordinary events at critical junctures. Sociopaths do exist. But the great majority of people reach stages four or five and are thus prepared to exist harmoniously — in Pleistocene hunter-gatherer camps.
If it is true that ontogeny recapitulates phylogeny, then can we expect the species to develop past the fifth stage?