Modelling disaster  

Matt Yglesias links to this fascinating application of standard economic models to the Bush tax cut. The stated conclusions don't leave much room for optimism.

While I'm obviously no friend of the Bush admin's tax policy, I should say that I'm highly skeptical of all this macroeconomic modelling and what it can say about the effects a big tax package like this one will have. The tax environment in the United States is extraordinarily complex, and before you can determine what effect a particular change will have, you have to control for all the other policies already in effect.