Chess-Playing Programs and the Problem of Complexity

Man can solve problems without knowing how he solves them. This simple fact sets the conditions for all attempts to rationalize and understand human decision-making and problem-solving. Let us simply assume that it is good to know how to do mechanically what man can do naturally — both to add to man's knowledge of man, and to add to his kit of tools for controlling and manipulating his environment. We shall try to assess recent progress in understanding and mechanizing man's intellectual attainments by considering a single line of attack — the attempts to construct digital computer programs that play chess. Chess is the intellectual game par excellence. Without a chance device to obscure the contest, it pits two intellects against each other in a situation so complex that neither can hope to understand it completely, but sufficiently amenable to analysis that each can hope to outthink his opponent. The game is sufficiently deep and subtle in its implications to have supported the rise of professional players, and to have allowed a deepening analysis through 200 years of intensive study and play without becoming exhausted or barren. Such characteristics mark chess as a natural arena for attempts at mechanization. If one could devise a successful chess machine , one would seem to have penetrated to the core of human intellectual endeavor. The history of chess programs is an example of the attempt to conceive and cope with complex mechanisms. Now there might have been a triek — one might have discovered something that was as the wheel to the human leg: a device quite different from humans in its methods, but supremely effective in its way, and perhaps very simple. Such a device might play 39