I think a substantial phased increase in the federal gasoline tax of the sort called for by The New York Times would have been great, forward-thinking policy if adopted 20 years ago. And if I were, say, appointed to fill a vacant Senate seat I’d certainly be willing to vote for one. But given what we’ve learned about the risks of catastrophic climate change, it also seems like a concept that’s been somewhat overtaken by events. A carbon tax, or a cap on greenhouse gas emissions with auctioned permits, would constitute a tax on gasoline among other things. And there’s no particular reason that burning fuel in a car should be disfavored versus other carbon-intensive activities.