Dominic Lawson: Why artificial intelligence is never enough

The greatest games have a definite beauty, hard as it is to explain to non-chess players

A 31-year-old Russian will spend the next seven days attempting to demonstrate that even in the silicon age, a human can still outthink the computer. Vladimir Kramnik, the undisputed chess champion among carbon-based life forms, is playing a six-game match in Bonn against Deep Fritz, the most powerful chess program ever linked to a PC. Powered by the Intel Core Duo 5160 system, Deep Fritz scours the chess board at a speed of 8 million positions per second. Unfortunately for its German programmers, this barely begins to scratch the surface of a solution to the problem known as chess.

One of the many legends about the origins of the game is that it was invented by the Indian king Shirham's grand vizier, Sissa Ben Dahir. Invited by the king to propose a reward, the vizier asked for one grain of wheat for the first of the board's squares, two grains for the second, four grains for the third, eight for the fourth, and so on up to the 64th and final square. "Is that all, Sissa, you fool?" asked the king. His vizier pointed out: "I have asked for more wheat than you have in your entire kingdom, more wheat than could be collected by covering the whole surface of the earth." This demonstration of the exponential nature of chess can be expressed less parochially: the number of potential positions that could occur once a game has started is in the order of 10 to the power of 128, overwhelmingly larger than the number of atoms thought to be contained in the known universe.

With the help of algorithms which cut off obviously pointless searches, the latest generation of programs avoids a vast number of redundant calculations. As a result, Deep Fritz is now about the same playing strength as Kramnik and possibly stronger; but the most interesting question remaining is simply this: is the machine really playing chess? This is analogous to the test proposed by Alan Turing, who in 1950 wrote the very first chess program. Turing asserted that a machine could be said to be thinking only if, when concealed from an observer, that observer would be unable to distinguish the words or "thoughts" it produced from those which might have emerged from a person.

Turing's test is still at the heart of man's attempt to create artificial intelligence, which is why Kramnik v Fritz is of more than sporting interest. For what it is worth, my own view is that all chess programs to date fail the Turing test, and for one reason: although many of their individual moves are exactly what a remarkably good human would play, I have never seen an entire game by a computer which could be described as a work of art. The greatest games played by humans have a definite beauty, hard as is it is to explain to non-chess players. Imagine a Bach fugue, and it's something like that: an almost geometric aesthetic with the power to lift the spirit.

Over the 64 squares of the chessboard, no human demonstrated such artistry more dazzlingly than a man whose 70th birthday has just been marked in his home town of Riga. Only there was never the slightest chance that Mikhail Tal would have survived to join in the celebrations. Tal was prey to the vices which are often associated with the creative temperament. To say that he was an addictive personality would be an understatement. He smoked up to 100 cigarettes during each game; according to his first wife, he never owned a lighter because he always lit the next cigarette with the butt of the last one. He was an alcoholic, although he never touched wine: when he came to this country in 1973 for the annual Hastings grandmaster tournament, he astounded the barman at the seafront hotel he stayed in by drinking the establishment out of its entire stocks of whisky and brandy.

The acute physical pain he suffered after operations designed to clear up the havoc caused by his drinking led to another addiction. His friend, Gennadi Sosonko, recalls: "Misha became addicted to morphine. The veins on his arms were black and blue, and nurses tried in vain to find a place that had not yet been touched." Tal had other weaknesses too: it was typical that when asked to define the pleasures of chess, he once replied: "Just as one's imagination is stirred by a woman's smile, so it is stirred by the possibilities of chess."

It was hardly surprising that, after becoming the youngest-ever world chess champion in 1960, Tal was prevented by ill-health from retaining his ranking as the world's strongest player. The surprising thing was that, despite spending much of his time in an alcoholic haze, he remained, until his death in 1992, one of the very best. Indeed, three weeks before his much-abused organs packed up for good, he escaped from hospital to play a "blitz" tournament in Moscow, in which he was the only player to defeat the then world champion, Garry Kasparov.

In his book My Great Predecessors, Kasparov pays an eloquent tribute to Tal. "He is the only player I can remember who did not calculate lengthy variations: he simply saw them! Hundreds of fantastic combinations were constantly whirling around in his brain and his imagination knew no bounds. There was something Mephistophelian in his penetrative stare at the board."

There certainly was: for those who are YouTube afficionados, I can recommend a brief clip of Tal playing the teenage Bobby Fischer. The look that Tal gives the American wunderkind at the start of the game is indeed devilish. In the same tournament, the Hungarian grandmaster Benko attempted to deflect Tal's lethal gaze by wearing dark glasses. Tal, who had a rich sense of satire, promptly sent out for some peculiarly grotesque Edna Everage-type spectacles, which he put on, causing Benko to humiliate himself further with a pointless complaint to the event's organisers.

I saw Tal only when he was in his 50s; he looked about 25 years older. I would scarcely have recognised him, except for two things: in his left hand he held a cigarette in his inimitable fashion, and his claw-like right hand that moved the pieces around the board with astonishing rapidity had only three, unusually large, fingers; this was a congenital deformity. Actually, there was a third sign that this human wreckage was Tal. Around the board there was a cluster of other grandmasters: there always were, hoping that some of his genius might rub off on them.

Vladimir Kramnik paid Tal what must be the greatest of all tributes in this month of his 70th anniversary: "He was like a man from another planet. That's why his chess was unidentifiable. Analysing his games is tantamount to discussing what God looks like." What vice-free computer could ever earn such an accolade?

d.lawson@independent.co.uk