I GOT MY FIRST GLIMPSE OF ARTIFICIAL INTELLIGENCE ON Feb. 10, 1996, at 4:45 p.m. EST, when in the first game of my match with Deep Blue, the computer nudged a pawn forward to a square where it could easily be captured. It was a wonderful and extremely human move. If I had been playing White, I might have offered this pawn sacrifice. It fractured Black's pawn structure and opened up the board. Although there did not appear to be a forced line of play that would allow recovery of the pawn, my instincts told me that with so many "loose" Black pawns and a somewhat exposed Black king, White could probably recover the material, with a better overall position to boot.
But a computer, I thought, would never make such a move. A computer can't "see" the long-term consequences of structural changes in the position or understand how changes in pawn formations may be good or bad.
Humans do this sort of thing all the time. But computers generally calculate each line of play so far as possible within the time allotted. Because chess is a game of virtually limitless possibilities, even a beast like Deep Blue, which can look at more than 100 million positions a second, can go only so deep. When computers reach that point, they evaluate the various resulting positions and select the move leading to the best one. And because computers' primary way of evaluating chess positions is by measuring material superiority, they are notoriously materialistic. If they "understood" the game, they might act differently, but they don't understand.
So I was stunned by this pawn sacrifice. What could it mean? I had played a lot of computers but had never experienced anything like this. I could feel--I could smell--a new kind of intelligence across the table. While I played through the rest of the game as best I could, I was lost; it played beautiful, flawless chess the rest of the way and won easily.
Later I discovered the truth. Deep Blue's computational powers were so great that it did in fact calculate every possible move all the way to the actual recovery of the pawn six moves later. The computer didn't view the pawn sacrifice as a sacrifice at all. So the question is, If the computer makes the same move that I would make for completely different reasons, has it made an "intelligent" move? Is the intelligence of an action dependent on who (or what) takes it?
This is a philosophical question I did not have time to answer. When I understood what had happened, however, I was reassured. In fact, I was able to exploit the traditional shortcomings of computers throughout the rest of the match. At one point, for example, I changed slightly the order of a well-known opening sequence. Because it was unable to compare this new position meaningfully with similar ones in its database, it had to start calculating away and was unable to find a good plan. A human would have simply wondered, "What's Garry up to?," judged the change to be meaningless and moved on.