I’d like to introduce you to two friends of mine, Mr. Bentham and Mr. Hume.

Mr. Bentham knows everything. He went to Stanford, then to the Kennedy school before getting a business degree. He’s got multivariate regressions coming out of his ears, and he sprinkles C.B.O. reports on his corn flakes for added fiber.

Mr. Hume is very smart, too, but he doesn’t seem to make much use of his intelligence. He worked on Wall Street for a little while, but he never could accurately predict how the market was going to move tomorrow or the day after that.

Mr. Bentham is a great lunch partner. If you ask him to recommend a bottle of wine, he’ll reel off the six best vintages on the wine list, in ranked preference. Mr. Hume can’t even tell you which entree to order because he doesn’t know what you like.

If you put Mr. Bentham in charge of the government, he’d proceed with confidence. If you told him to solve a complicated issue like the global-warming problem, he’d gather the smartest people in the country and he’d figure out how to expand wind, biomass, solar and geothermal sources to reduce CO2 emissions. He’d require utilities to contribute $1 billion a year to a Carbon Storage Research Consortium. He’d draw up regulations determining how much power plants would be allowed to pollute.