Ezra Klein makes a great point from his new perch at The Washington Post, pivoting off Bruce Bartlett's latest book, The New American Economy:
[P]olitical movements have a tough time recognizing when they're full. After all, eating worked so well last time. Elections were won on a pro-eating platform. Supporters were convinced of the virtues of eating. This movement is now about eating. Or, as the case might be, lower taxes. Bartlett argues that conservatives were right about the need for lower taxes and less regulation in the 80s. He, after all, was one of them. But then they succeeded in lowering taxes and dismantling regulations. They left the country full. Since then, the problems requiring policy solutions have changed. But the movement's prescriptions haven't.
Ezra points out that the reason the Clinton alumni running Obama's economic policy have succeeded so far is that they've similarly updated their worldviews to suit the moment. I agree, though I'd argue that the stimulus itself didn't require that big an adjustment, since most of these guys have always believed in countercyclical spending. (The spending related to longer-term investments probably required more updating). I think the bigger test will come with the just-emerging regulatory agenda--and the early indications are that Summers, Geithner et al have adjusted their views in response to a pretty important change in the facts on the ground.