Piaget examines all the thought on the subject of evolution since Darwin's day. He pinpoints the spots where the various theories do not hold up. This analysis leads him to his own theory. In my view, his theory coincides with my own sense of how change, which is an activist one. In other words, I have something to do with it.
Piaget has his roots in the observation of his own children, and, whereas most of Sciience argues from massive samples, Piaget remains rooted in the significance of individual behavior. Thus his theory itself has moral implications--- if my behavior makes a difference I will be more likely to consider it carefully and act constructively.