Robert S. Siegler Carnegie Mellon University
I recently read a particularly incisive description of the goals of developmental psychology. It included the following description:
The eventual goal of developmental psychology is to provide a single theory that describes the whole of development. However, the approach most scientists actually follow is to separate the problem into two parts. First, there are the laws that tell us how the child changes with time. (If we know what the child is like at any one time, these laws tell us how it will look at any later time.) Second, there is the question of the initial state of the child. (pp. 10-11)
Actually, the original text did not read quite this way. It used the term science rather than developmental psychology and universe rather than child. The substitutions that I made were necessary because the passage was written not to describe the goals of developmental psychology, but rather the goals of astrophysics. The statement came not from any book on child development, but rather from Stephen Hawking ( 1988) A Brief History of Time. Nonetheless, the description captures the deepest goals of our field as well as Hawking's. The two fundamental properties we would like to see in a theory of development are a characterization of the child at the beginning of development and a characterization of the laws that govern changes after that point.
Selection of "modularity and constraints" as the theme of the Minnesota Symposium attests to the prominence these constructs have assumed within developmental psychology. I suspect this prominence reflects in large part the promise of the constructs for moving us toward the two main goals cited earlier. They promise to tell us both about the