Footballing robots will never bend it like Beckham

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David Beckham’s career exemplifies the paradox of expertise – the true expert cannot explain how he does it.

The highlight of David Beckham’s just-finished career as England soccer captain was the goal against Greece that kept his team in contention for the 2002 World Cup. While England fans were celebrating in the streets, scientists at the UK’s University of Sheffield were in their wind tunnels. “The shot left his foot at 80mph from 27 metres out, moved laterally over two metres during its flight due to the amount of spin applied, and during the last half of its flight suddenly slowed to 42mph, clipping the top corner of the goal,” explained Matt Carre, a specialist in computational fluid dynamics.

“Becks a physics genius” proclaimed one tabloid headline, as Mr Carre went on to claim that “Beckham was instinctively applying some very sophisticated physics calculations”. While Mr Carre’s explanation of the ball’s trajectory makes perfect sense, his explanation of how Beckham came to do it does not. No one can solve differential equations instinctively – certainly not Beckham, who is definitely not a physics genius.

Beckham is an extreme example of someone with exceptional skill who is quite unable to explain the basis of that skill, supremely talented but almost wholly inarticulate. But all genuine expertise has this character. If what the expert does could be reduced to rules, then others could do it and we would no longer distinguish the expert from the everyday performer. For Wittgenstein as for Beckham, for Gary Kasparov as for Jane Austen, we see what they do but that is not sufficient to allow them, or us, to understand how they do it.

A famous experiment by Gary Klein, the American decision scientist, showed videos of experienced and novice paramedics. Experienced paramedics, and the general public, could easily tell which was which. The paramedics recognised proficiency and the lay people recognised confidence. But teachers of paramedic skills found it harder to pick out the pros. The trainers looked for adherence to the rules they taught, which the experienced practitioners would often break. The rules were not wrong and the teachers were right to require novices to follow them. It is only once you are thoroughly familiar with a skill that you can develop it. But with genuine expertise comes knowledge that is not rule-based.

It is tempting to think there is some higher level of rules – rules for when to break the rules. This idea motivated the long search for artificial intelligence, in the hope that by learning from the performance of experts, computers could ultimately take over all human functions. But, at least in that form, the artificial intelligence project has failed. Mr Carre said that Beckham was “really” applying sophisticated physics calculations. But he is not just an early prototype of a footballing robot. Human judges and talented sports people do something different from what computers and robots do, even if we are not quite sure what it is.

This does not mean that intuition is preferable to calculation, still less that all claims to expertise based on experience and the approval of one’s peers are justified. Two weeks ago, I described Phillip Tetlock’s discouraging findings on political judgment. Most pundits were no good, and the more famous pundits were worse. Computers primed to ask a few simple questions have a better diagnostic record than most physicians. The defensive nature of claims to expertise is hardly surprising; if experts do not believe in their own expertise, why should anyone else? But we are convinced of Beckham’s skills not because he made it to captain of the team, but because of his proven record in scoring goals. The same principle applies, or should apply, in the worlds of politics, business and finance.

Beckham was picked out at an early age for his sporting potential, and his footballing skills were developed in years of formal training and practice. His natural talent and developed prowess is another demonstration of Darwin’s dangerous idea – that natural selection can produce results beyond the capacity of human ingenuity to emulate. That is why the next England captain will be a young tongue-tied sportsman rather than a professor of computational fluid dynamics.

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