How many jellybeans?

David Runciman

  • Profiles, Probabilities and Stereotypes by Frederick Schauer
    Harvard, 359 pp, £19.95, February 2004, ISBN 0 674 01186 4
  • The Wisdom of Crowds: Why the Many are Smarter than the Few by James Surowiecki
    Little, Brown, 295 pp, £16.99, June 2004, ISBN 0 316 86173 1

Most of us, most of the time, are deeply prejudiced in favour of individual over collective judgments. This is hardly surprising, since we are all biased. First, we are biased in favour of our own opinions, which we tend to prefer to those of anyone else. Second, we are biased in favour of individuals generally, because we are all individuals ourselves, and so are broadly sympathetic to the individual point of view. We like to think of people exercising their personal judgment, and not just blindly following the rules. For example, who wouldn’t prefer, when appearing before a judge, to learn that the judge was willing to hear each case on its merits, and exercise some discretion if necessary? General rules, we think, are likely to be discriminatory, because they cannot take account of special circumstances. Individuals, by contrast, can use their own judgment, and make exceptions.

However, as Frederick Schauer argues in his excellent book, though we are right to suspect that all general rules are discriminatory, we are wrong to suppose that it is therefore better to trust to individuals. This is because no individual is truly capable of judging each case on its merits; individuals simply bring their own personal generalisations to bear on the case in question. These are likely to be just as crude and inflexible as the mandatory guidelines of some far distant committee. It is easy to forget this. Because general rules are cold and impersonal, the injustices they inevitably create seem crueller and more pernicious. Schauer gives various examples, including the cases of perfectly friendly dogs put down because they fell foul of the terms of dangerous dog regulations, or airline pilots forced by United States law to retire at the age of 60, regardless of their proficiency, expertise and general good health. It is not only airline pilots who think this latter rule absurd. The first commercial flight into space was piloted this June by a 63-year-old who had been forced to quit his day job as a domestic airline pilot. When he appeared on the Jay Leno show to publicise this feat, he pointed out that he was available to fly in space only because the government had deemed him unfit to fly underneath it. How the audience laughed at this spectacle of a bureaucracy gone mad, that a man should have been reduced by ageism to becoming an astronaut.

Because of glaring examples such as this, it is tempting to think that there must be some way of deciding who is and who is not fit to fly that would not be so inflexible and discriminatory. Why not test pilots when they reach 60, for example, to see if they are fit to carry on? But, as Schauer points out, specialised tests rely no less on generalisations than general rules. A blood pressure test designed to ascertain the likelihood of sudden incapacitation will seem discriminatory to anyone who falls below its arbitrary threshold and then goes on to enjoy thirty more years of healthy existence. So why not dispense with formal tests, and simply get individual doctors, perhaps in conjunction with other experienced pilots, to exercise their own judgment in assessing a person’s fitness to carry on after the age of 60? The answer is that these individuals will simply be applying their own generalisations, and these are likely to be as arbitrary as any. Some doctors will be particularly alert to incipient heart trouble; others will be on the look out for mental instability; some pilots will simply prefer those of their colleagues who remind them of themselves (I like a drink now and then, and I can still fly, so why not this guy?). These are the very reasons we have general rules in the first place, to save us from the arbitrary judgments of individuals.

This does not mean that it is impossible to argue against general rules on the grounds that they could be fairer – a law that forced pilots to retire when they went bald, or converted to Islam, would clearly be grotesque. What it does mean, though, is that it does not make sense to argue against general rules on principle, simply because they are general. What matters is to distinguish between what Schauer calls spurious and non-spurious generalisations. Spurious generalisations include those where there is no statistical correlation (as in the case of baldness and flying ability), as well as those where the correlation is irrelevant (it is true that in recent years a high percentage of aircraft to crash in the United States have been piloted by Muslims, but the non-spurious fact is that they were also piloted by terrorists, who should certainly be prevented by law from flying aeroplanes).

What matters is to decide which non-spurious generalisations are useful in making the general rules. By no means all of them are useful. For example, it is almost certainly true that there are non-spurious generalisations to be made about the likelihood of certain types of passengers posing a threat to airline security, on the basis of age, gender and ethnic background – the likeliest terrorists are young males of Middle Eastern origin. But it does not follow that young males of Middle Eastern origin should be singled out as a general rule for special attention from security officers. This is because individual security officers are likely to have devised such a rule for themselves, which they would apply, and probably over-apply, regardless. More useful would be guidelines that identified other dangerous groups who might be missed (other kinds of terrorist, other kinds of criminal, other kinds of security threat). Once it is clear that all judgments, including all individual judgments, rest on various kinds of generalisation, rules can be devised that take account of the inadequate generalisations of individuals.

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