Three paradigms for computer-aided design

As the field of computer-aided design has developed over the last thirty years or so, three clear paradigms have successively emerged. First, designing was conceived of as a problem-solving activity. Then, as the limitations of this view became increasingly apparent, designing was seen more as a knowledge-based activity. (This is the perspective of most of the papers in this journal issue.) Now, there is a growing consensus that designing must be treated as a fundamentally social activity - a matter of multiple, autonomous but interconnected intelligences in complex interaction. Here I shall characterize and compare the three paradigms, discuss the implications of the newest of these, and go on to suggest some directions for the future applications of artificial intelligence techniques in design.