CAN MACHINES THINK?

WHEN GARRY KASPAROV FACED OFF AGAINST AN IBM COMPUTER in last month's celebrated chess match, he wasn't just after more fame and money. By his own account, the world chess champion was playing for you, me, the whole human species. He was trying, as he put it shortly before the match, to "help defend our dignity."

Nice of him to offer. But if human dignity has much to do with chess mastery, then most of us are so abject that not even Kasparov can save us. If we must vest the honor of our species in some quintessentially human feat and then defy a machine to perform it, shouldn't it be something the average human can do? Play a mediocre game of Trivial Pursuit, say? (Or lose to Kasparov in chess?)

Apparently not. As Kasparov suspected, his duel with Deep Blue indeed became an icon in musings on the meaning and dignity of human life. While the world monitored his narrow escape from a historic defeat--and at the same time marked the 50th birthday of the first real computer, ENIAC--he seemed to personify some kind of identity crisis that computers have induced in our species.

Maybe such a crisis is in order. It isn't just that as these machines get more powerful they do more jobs once done only by people, from financial analysis to secretarial work to world-class chess playing. It's that, in the process, they seem to underscore the generally dispiriting drift of scientific inquiry. First Copernicus said we're not the center of the universe. Then Darwin said we're just protozoans with a long list of add-ons--mere "survival machines," as modern Darwinians put it. And machines don't have souls, right? Certainly Deep Blue hasn't mentioned having one. The better these seemingly soulless machines get at doing things people do, the more plausible it seems that we could be soulless machines too.

But however logical this downbeat argument may sound, it doesn't appear to be prevailing among scholars who ponder such issues for a living. That isn't to say philosophers are suddenly resurrecting the idea of a distinct, immaterial soul that governs the body for a lifetime and then drifts off to its reward. They're philosophers, not theologians. When talking about some conceivably nonphysical property of human beings, they talk not about "souls" but about "consciousness" and "mind." The point is simply that as the information age advances and computers get brainier, philosophers are taking the ethereal existence of mind, of consciousness, more seriously, not less. And one result is to leave the theologically inclined more room for spiritual speculation.

"The mystery grows more acute," says philosopher David Chalmers, whose book The Conscious Mind will be published next month by Oxford University Press. "The more we think about computers, the more we realize how strange consciousness is."