If the person has intrinsic needs, then the person grows from the inside out. Every normal child has the potential to be fully a person, just as every normal acorn has the potential to be fully an oak tree and every normal kitten has the potential to be fully a cat. Powered by the intrinsic system of needs described above, the child seeks satisfaction for them. In an appropriate environment, children are able to satisfy those needs and thus realize their human potential. The basic project of the child is to become an adult - not any old adult but a great and good adult. We therefore need to 'explain' not the genius of a Pablo Picasso or a Margaret Mead (or whoever you think has most fully realized the human potential) but rather why we are not all Picassos or Meads. We need to explain not growth itself (this is simply the unfolding of the intrinsic potential) but the stunting of growth. Here are two alternative explanations.

Conflict between needs - Freud

      The process of realizing the human potential is so long and so complex that many things can go wrong. It is relatively easy for an acorn to become fully an oak tree and for a kitten to become fully a cat, but it is not so easy for a child to become fully a person. The theory of Sigmund Freud could be considered as a dramatic documentation of the many things which can go wrong.

      His id, superego, and ego represent the forces striving for the satisfaction of biological, sociological, and psychological needs, respectively. Although those forces are naturally in harmony, as argued above, Freud shows how they come into conflict.

      Since the ego tries to maximize truth and since the id tries to maximize pleasure, they come into conflict when truth and pleasure are incompatible. Berelson and Steiner, in summarizing scientific findings about human behavior, describe the human being as 'a creature who adapts reality to his own ends, who transforms reality into a congenial form, who makes his own reality'. In the conflict between truth and pleasure, it seems then that pleasure usually wins.

      Since the ego is concerned with laws and the superego is concerned with rules, they come into conflict when laws (propositions created by humans to describe the world) and rules (propositions created by humans to prescribe their conduct in that world) are incompatible. Studies of conformity suggest that, in the conflict between laws and rules, rules usually win.