Looking for something cool to read? Try this article by Malcolm Gladwell in this week’s New Yorker. Gladwell discusses an unusual intersection of policy, politics, and mathematics — namely, social ills that follow the "power law," in which a relative handful of bad actors are responsible for the bulk of a problem. Take, for example, pollution from cars:

Most cars, especially new ones, are extraordinarily clean. A 2004 Subaru in good working order has an exhaust stream that’s just .06 per cent carbon monoxide, which is negligible. But on almost any highway, for whatever reason — age, ill repair, deliberate tampering by the owner — a small number of cars can have carbon-monoxide levels in excess of ten per cent, which is almost two hundred times higher. In Denver, five per cent of the vehicles on the road produce fifty-five per cent of the automobile pollution. [Emphasis added.]

The problem, according to Gladwell, is that even if the lion’s share of problem is caused by the statistical outliers, our solutions tend to treat everyone the same — as if we’re all equally responsible. The patina of fairness may be reassuring to politicians. But substantively, fairness doesn’t always lead to the best outcomes.

We deal with emissions, for example, by requiring each car — even the cleanest models — to be tested every year or two. For dirty cars, that’s not often enough: A polluting car in need of repair can stay on the road for quite a while before anyone checks on it. But for owners of relatively clean cars, the vehicle emissions test is just a time-wasting formality. And all the while, it’s easy enough to monitor a vehicle’s emissions from the roadside as the car passes, which would let police pull over polluters as if they were speeders. The technology’s been around for decades. All that’s missing, apparently, is the political will, or maybe the creativity, to make it happen.

Of course, there’s plenty of reason to be cautious here. The most polluting cars tend to be owned by the most economically vulnerable among us; pulling them over for polluting would just add to their burdens. But here, too, Gladwell’s approach to "power law" problems might offer a solution: Offering free repairs, or letting the owner of a severely polluting vehicle trade it in for a non-polluting one at no cost, might well be cheaper than maintaining the existing vehicle inspection system. Of course, it hardly seems fair to deal with this sort of problem by handing out clean cars or free repairs; that’s a benefit that the rest of us certainly didn’t get. But for some things, fairness and efficiency don’t always go hand in hand; sometimes we have to choose one or the other.

(Oh, and just to be clear, I don’t know that I agree that .06 percent carbon monoxide is "negligible," as Gladwell says. For any individual car it may be. But there are an awful lot of cars out there, cumulatively producing an awful lot of CO. Even if you could get rid of the outliers, I’m sure that people who live near highways and busy streets would be grateful to get those emissions down.)