TEACHABLE MOMENTS. The Instapundit's Tech Central column is up.

Today's sport-utility fad (now fading in light of high gas prices) was as much the creature of government policy as of consumer preference: Sport-utes took the place of the big station wagons favored by an earlier generation of suburbanites, not least because CAFE standards applied to station wagons but not to "trucks," a class that included sport-utility vehicles. (They also got a break on safety rules, and more favorable tax treatment). I suspect that the Law of Unintended Consequences will apply to any future regulatory efforts along these lines, too, and that the best thing to do is to let the market decide. If people still want sport-utes when gas is pushing $3.50 a gallon, they must feel that they're pretty worthwhile.

Likewise, proposals for more commuter-rail lines seem to miss the point. The problem with "commuter rail" systems is that they presuppose commuters, and the changing U.S. economy makes traditional commuting -- in which armies of workers flock from suburbs to downtowns in the morning, and back home in the evenings -- less significant. While there are still plenty of people who commute this way, there are a lot more people who work in edge cities, or from home, or who keep irregular hours and run a lot of errands, for whom commuter rail systems aren't likely to do
much good.

In the introductory course, we started with the Principle of Substitutes today, with the Principle of Complements to come on Friday. I continue to do some thinking, in the odd spare moment, about the economics of suburbs. Irreversible investments and dual immigration tracks first.