Do humans improve their moral reasoning as they mature, or at least do they have the potential to gradually develop a superior morality? Confucius and Aristotle ideas felt that way. Jean Piaget (a Swiss psychologist 1896 -1980) developed a theory of stages of moral development in children. Lawrence Kohlberg (1927 – 1987) carried Piaget’s work further with a modified model going into adulthood — and it is perhaps now one of the most popular models. And of course there are other models. To the right is Kohlberg’s model and you can see some other outlines here.
But I am skeptical about progress, moral or otherwise. I view each human as having many different moral calculators in their mind. Indeed, the development of the calculators occur at different times for different folks, but I think we all maintain many calculators. See my post on the Moral Mind. So it is not that we progress into different moral spheres, but I think we use these different calculators depending on the situations we find ourselves. Some may use one or more calculator more often than others, and indeed some may have never developed some calculators, but we all use more than one calculator and more often than we think. We like to think of ourselves as more homogenous: of having one set of beliefs, of having one set of morality and such but we are many selves — we are much more complicated.
I think it is a mistake to look at these as a pyramid or as progress, instead, each calculator has its own unique set benefits and its own set of shortcomings, depending on the situation — that is why so many have evolved.