Petey on Matt Yglasias's blog comments points to this good little article by James Surowiecki in this month's New Yorker.

Surowiecki makes several good points about collective action problems. He keeps his discussion very specific to the question of SUV's and mileage standards, but it's actually a very general problem.

There are literally dozens, or hundreds, of situations like this. It's all an expression of the old concept of the Tragedy of the Commons. Briefly, the TotC refers to the old problem of the commons in old English villages, which were pastures publicly owned by the town. They were available to use animals for grazing. Inevitably, what would happen is that every farmer would try to maxmize the time their animals spent grazing on the commons, which meant they were overgrazed, and soon destroyed. What was needed was an agreement by all parties to limit their grazing time to preserve this valuable resource for everyone's use.

Unfortunately, every farmer had strong incentives to cheat such an agreement, since his animals would get more food, and be healthier. This is one of the basic arguments for the principle of a central government; to force people to take collective action that it is in everyone's best interest to make happen, and to prevent cheaters from free riding; that is, from drawing benefits without paying into the system.

Even conservatives agree with this concept, to some extent, when they support the concept of a strong defense. Defense is an issue where it's in my best interests to have it, but it's inefficient for me to pay for it on my own. Besides, if all my neighbors team up to defend the neighborhood, I get it for free. But they all, knowing that, are unlikely to want to pay into such a system. So you have to have a central government that ensures that everyone is paying into the pot, and then provides the services.

Sadly, the same incentives are exponentially multiplied when it comes to the question of safety and SUV's. SUV's are not, in and of themselves, safer cars. In a single-car accident, you are about as likely to die in an SUV as you are in a sedan, due mostly to the vehicle's increased weight (hence increased likelihood of high speed loss of control) and highly-increased likelihood of rollover. However, in a 2 or more car crash, what being in an SUV really does is make you into a killin machine. If you are in an SUV involved in a crash with a sedan, you are something like 6 times as likely to kill the passengers in the other car than your passengers are to die.

So, people mistakenly bought SUV's for safety purposes, but now that they make up something like half of all cars on the road, it really is a safety concern, because you, as a sedan driver, are so much more likely to be killed if you are in an accident with an SUV.

Of course, this has also spawned the eeevil era of the mega-SUV, since the only way to be safer when in a wreck with, say, an Explorer is to driving an Excursion!