Mallaby might think this makes him a member of the Pigou Club. Sorry: the argument here is too squishy to qualify.
But there's one antidote to loneliness that is at least intriguing. In an experiment in Austin, Princeton's Daniel Kahneman found that commuting -- generally alone, and generally by car -- is rated the least enjoyable daily activity, but commuting by car pool is reasonably pleasant. Measures that promote car pooling could make Americans less isolated and healthier.
So here's my slogan for 2008: Gas taxes make you happy.
There is no externality here that I can see. My friend Jeff Miron and I live in the same Boston suburb, and we could commute to Harvard together if we wanted. While I would enjoy Jeff's company (and perhaps with enough carpooling I could talk him out of some of his loonier libertarian ideas), I also enjoy the autonomy I get from not having to coordinate with someone else. There are pros and cons to carpooling, and Jeff and I don't need the government to prod us to make the efficient decision. The Coase theorem should work just fine here. Mallaby's policy is the sort of social engineering that offends even namby-pamby libertarians like me.
I am, however, a forgiving sort. I will happily reconsider Mallaby's application for membership after a future column. Consider this a revise-and-resubmit.