Demagogue

President Bush wrote in a Wall Street Journal op-ed Wednesday that "it is also a fact that our tax cuts have fueled robust economic growth and record revenues." The claim about fueling record revenue is flat wrong, and it is shocking that the president should persist in making such errors. After all, tax cuts are the central plank of his domestic policy. How can he fail to understand the basic facts about them?

This is not just our opinion. Harvard's N. Gregory Mankiw, an economic conservative who served as chairman of Mr. Bush's Council of Economic Advisers, has tested the hypothesis on which Mr. Bush's claim is based: He looked at the extent to which tax cuts stimulate extra growth and the extent to which that growth generates extra tax revenue that offsets the initial loss of revenue from the tax cut.

Mr. Mankiw's conclusion: Even over the long term, once you've allowed all of the extra growth to feed through into extra revenue, cuts in capital taxes juice the economy enough to recoup half of the lost revenue, and cuts in income taxes deliver a boost that recoups 17 percent of the lost revenue.

So a $100 billion cut in taxes on capital widens the budget deficit by $50 billion, and a $100 billion cut in income taxes widens the budget deficit by $83 billion.