Supply-side guru Arthur Laffer has an op-ed in the Wall Street Journal making the case for the fantasy that tax cuts increase revenue:

In the 1920s, the highest federal marginal income tax rate fell to 24% from 78%. Those people who earned over $100,000 had their share of total taxes paid rise — from 29.9% in 1920 to 48.8% in 1925, and then to 62.2% in 1929. There was no inflation over this period.

With the Kennedy tax cuts of the 1960s, when the highest tax rate fell from to 70% from 91%, the story was the same. When you cut the highest tax rates on the highest-income earners, government gets more money from them, and when you cut tax rates on the middle and lower income earners, the government gets less money from them.

Even these data grossly understate the total supply-side response. A cut in the highest tax rates will increase lots of other tax receipts. It will lower government spending as a consequence of a stronger economy with less unemployment and less welfare. It will have a material, positive impact on state and local governments. And these effects will only grow with time.

The suggestion of a political conspiracy against his ideas in the concluding paragraph (which follows directly) is the best part, however:

Trained economists know all of this is true, but they try to rebut the facts nonetheless because they believe it will curry favor with their political benefactors.

So why have current and former Bush administration economists publicly contradicted President Bush and other administration officials who claim tax cuts increase revenue? They have no political incentive to do so. And what about the overwhelming majority of economists with no political ties who agree with them?