The goal, Mr. Furman explained, is to establish a “a basic issue of tax fairness.” Millionaires should pay an effective tax rate no lower than a middle-class secretary or a plumber. But wait: IRS data show that middle-class workers on average pay just under 15% of their income in federal taxes, while the richest 0.1% pay almost twice as high a rate on average, or 26%.

The U.S. already has a Buffett rule. The Alternative Minimum Tax that first became law in 1969 was also supposed to make sure that millionaires pay their “fair share.” The top AMT rate is now 28%. But the AMT has become a public nuisance, adding new complexity to the tax code and ensnaring more and more middle-class families because it isn’t indexed for inflation. The surest prediction in politics is that any tax that starts by hitting the rich ends up hitting the middle class because that is where the real money is.

An even greater absurdity is the White House claim that this is a first step to tax reform because it will ensure that the “rich don’t take advantage of tax breaks or structure their affairs to pay less taxes.” Huh?

A basic principle of any tax reform worth the name is to broaden the tax base in order to lower rates for everyone, not to raise them. The point is to make the tax code more efficient by reducing the incentive for avoidance—legal or illegal.