If Arithmetic Mattered in Budget Debates

We all know that folks involved in debates on economic policy are not very good at arithmetic. That's why almost no one was able to see the $8 trillion housing bubble that sank the economy. But we can always speculate about what the world would look like if arithmetic mattered.

Right now, the Republicans are claiming that cutting the corporate income tax rate from 35 percent to 20 percent will lead to a huge surge of investment and growth. They claim that the additional growth from this tax c...