My theory was that Karpov, as one of the finest technicians the game has ever seen, would hardly have made the schoolboy error of blundering into a stalemate by accident. He must have calculated that he didn't have enough time left on his clock to force mate, so played the quickest draw he could find before he overstepped the limit.
Aha! - my critics say - but the stalemate took three moves to accomplish, while White could have captured the last black pawn in only two; and by the rules of rapidplay, a player with a lone king cannot win a game on time. So if Karpov really wanted to insure himself against defeat, he would have played 1.Qc7 and 2.Qxa7.
A plausible argument, but it seems to me that it misses two vital points. The first of these is that captures take longer to make than ordinary moves. A piece may be slid from one square to another and the clock pressed with the same hand that moved it all in one elegant sweep. To pick up an enemy piece en route involves a good deal of time-wasting fumbling. Stephen R Gould had thought of that when he e-mailed us to suggest that Karpov might in fact, have blundered. He points out that a capture may be efficiently, if inelegantly, executed by striking the enemy piece with your own man with sufficient force to knock it from the board. The time lost is then negligible.
But would a world champion overlook such an obvious tactic? I deduced from the fact that Karpov did not plan in this manner that the game was played on a board that had a boundary extending higher than the surface of play. Any smitten piece would then run the risk of rebounding from the edge of the board and colliding with other pieces. After 1.Qc7 and 2.Q smites a7, the black pawn, if hit slightly below its centre, will rebound from the side and knock over the white pawn on a6. While White is trying to set up the men again, he will overstep the time limit.
And quite apart from the ridged boundary theory. I think we may also conclude that the clock was placed on the K-side. 1.Qh4 and 2.Qg3+ reduce to a minimum the path between hand and clock.
OK, I admit it: Karpov blundered. He still had seven seconds left at the end.