Of course Ryan Avent is right to say that you can't fully grasp the stupidity of the Bush line against energy conservation without mentioning the subject of externalities. When you burn coal or oil, or take up space on the road, current policy lets you get away with not paying the full cost of those endeavors. Under the circumstances, there are more coal plants and cars on the road than is socially optimal. Price this stuff correctly and people will use it less and we'll all be better off.