.... I am a proponent of carbon taxes. One criticism of this policy that you hear, for instance here from Noah Smith, is that they are pointless because you need international cooperation to make a real dent. But among non-tradeable goods this is not really the case. We don’t have to worry about transportation shifting abroad, since you can’t really outsource driving your car or shipping a package. And this matters, as transportation accounts for 70% of U.S. fuel consumption, and 30% of U.S. greenhouse gases. But even if carbon taxes are problematic, surely higher gas taxes are a good...