IN 1964 I moved from one world to another. For the previous five years I had lived in Alpine villages near Geneva, Switzerland, where I worked with Jean Piaget. The focus of my attention was on children, on the nature of thinking, and on how children become thinkers. I moved to MIT into an urban world of cybernetics and computers. My attention was still focused on the nature of thinking, but now my immediate concerns were with the problem of Artificial Intelligence: How to make machines that think?
Two worlds could hardly be more different. But I made the transition because I believed that my new world of machines could provide a perspective that might lead to solutions to problems that had eluded us in the old world of children. Looking back I see that the cross-fertilization has brought benefits in both directions. For several years now Marvin Minsky and I have been working on a general theory of intelligence (called "The Society Theory of Mind") which has emerged from a strategy of thinking simultaneously about how children do and how computers might think.
Minsky and I, of course, are not the only workers to have drawn on the theory of computation (or information processing) as a source of models to be used in explaining psychological phenomena. On the contrary, this approach has been taken by such people as Warren McCulloch, Allen Newell, Herbert Simon, Alan Turing, Norbert Wiener, and quite a number of younger people. But the point of departure of this book is a point of view -- first articulated jointly with Minsky -- that separates us quite sharply from most other members of this company: that is to say, seeing ideas from computer science not only as instruments of explanation of