President Obama has laid out the most ambitious and expensive domestic agenda since LBJ, and now all he has to do is figure out how to pay for it. On Tuesday, he left the impression that we need merely end "tax breaks for the wealthiest 2% of Americans," and he promised that households earning less than $250,000 won't see their taxes increased by "one single dime."

This is going to be some trick. Even the most basic inspection of the IRS income tax statistics shows that raising taxes on the salaries, dividends and capital...