The Wall Street Journal:

The political left always says Daddy Warbucks gets all the tax-cut money. So this is hardly news, except that the media are treating this joint Brookings Institution and Urban Institute analysis as if it’s nonpartisan gospel. In fact, it’s a highly ideological tract based on false assumptions, incomplete data and dishonest analysis. In other words, it is custom made for the Obama campaign. …

The heart of Mr. Romney’s actual proposal is a 20% rate cut for anyone who pays income taxes. This means, for example, that the 10% rate would fall to 8%, the 35% rate would fall to 28% and all the brackets in between would fall as well. The corporate tax would fall to 25% from 35%.

The plan says these cuts would be financed in a revenue-neutral way. First, by “broadening the tax base,” which means reducing or eliminating tax deductions and loopholes as in the tax reform of 1986. The Romney campaign doesn’t specify which deductions—no campaign ever does—but it has been explicit in saying that the burden would fall most on higher tax brackets. So in return for paying lower rates, the wealthy get fewer deductions.

Second, the Romney campaign says it expects to increase revenues by increasing the rate of economic growth to 4%, up from less than 2% this year and in 2011. (Separately from tax reform, but clearly relevant to budget deficits, Mr. Romney says he’d gradually reduce spending to 20% of the economy from the Obama heights of 24%-25%.)

The class warriors at the Tax Policy Center add all of this up and issue the headline-grabbing opinion that it is “mathematically impossible” to reduce tax rates and close loopholes in a way that raises the same amount of revenue. They do so in part by arbitrarily claiming that Mr. Romney would never eliminate certain loopholes (such as for municipal bond interest), though the candidate has said no such thing.

Based on this invention, they then postulate that Mr. Romney would have to do something he also doesn’t propose—which is raise taxes on those earning less than $200,000. In the Obama campaign’s political alchemy, this becomes “Romney Hood” and a $2,000 tax increase.

The Tax Policy Center also ignores the history of tax cutting. Every major marginal rate income tax cut of the last 50 years—1964, 1981, 1986 and 2003—was followed by an unexpectedly large increase in tax revenues, a surge in taxes paid by the rich, and a more progressive tax code—i.e., the share of taxes paid by the richest 1% rose.

For example, from 1980 to 2007, three tax rate cuts brought the highest marginal tax rate to 35% from 70%. Congressional Budget Office data show that when the tax rate was 70%, the richest 1% paid 18% of all federal income taxes. With the rate down to 35% in 2008, the share of taxes paid by the rich doubled to 40%.

The Tax Reform Act of 1986, which chopped the top income tax rate to 28% from 50%, was probably most similar to the Romney tax proposal because both were designed to lower rates and broaden the tax base. CBO and Martin Feldstein of the National Bureau of Economic Research found that the 1986 tax reform increased the share of taxes paid by the rich (to about 25% from 21% before the reform), in part because their reported taxable income rose as they lost tax shelters. Many businesses also changed their tax status from corporations to Subchapter S companies, thus paying taxes at the individual rate. This also increased the reported share of income declared, and tax paid, by the rich.

So on four separate occasions what TPC says is “mathematically impossible”—cutting tax rates and making the tax system more progressive—actually happened. Hats off to the scholars at TPC: Their study manages to claim that what happens in real life can’t happen in theory.

The TPC analysis also fails to acknowledge how highly dependent the current tax system is on the very rich. As the Tax Foundation explains in a recent report based on CBO data: “The top 20 percent of households pay 94 percent of federal income taxes. The bottom 40 percent have a negative income tax rate, and the middle quintile pays close to zero.” …

The study’s claims also rest on the assumption that tax cutting doesn’t increase economic growth. The study’s authors expose their own bias on this point by asserting that “the effects of tax rate reductions are likely to be small or even negative” over 10 years.

It’s certainly true that not all tax cuts have the same economic impact. But nearly all economists save for the most partisan liberals agree that cutting tax rates at the margin has the most bang for the buck. So how can the Tax Policy Center claim that cutting tax rates to increase incentives to work and invest has a “negative” impact? Not even the Keynesian economists who gave us the failed stimulus plan argue that the effect of tax cuts is negative.

Harvard economist Dale Jorgenson recently testified before the Senate Finance Committee that “a tax reform similar to the Reagan effort of 1986” would raise economic output over the long term “by $7 trillion in 2011 dollars.”

You can argue that Mr. Romney’s expectation of 4% GDP growth is too rosy, but the recent White House mid-session budget review predicts 4% growth in both 2014 and 2015 despite a huge tax increase next year. The Romney plan is far more realistic than that wish in the dark.

The Tax Policy Center’s claim that it’s impossible to make the numbers add up is also refuted by President Obama’s own Simpson-Bowles deficit commission report. The Romney plan of cutting the top tax rate to 28% and closing loopholes to pay for it is conceptually very close to what Simpson-Bowles recommended.

And here’s the kicker: Simpson-Bowles assumed that the top rate could be cut to 28%, loopholes could be closed, revenues as a share of GDP would rise to 20% and the deficit could be cut by close to $1.5 trillion. The difference is that the Romney plan caps tax revenues at about 18% of GDP so that taxes don’t have to rise on the middle class. If Mr. Romney’s numbers don’t add up, then neither do those in the bipartisan Simpson-Bowles plan that the media treat as the Holy Grail of deficit reduction.

What the Obama campaign and its acolytes at the Tax Policy Center are really saying is that tax reform that reduces rates and makes all income groups better off is impossible. This is a far cry from what Democrats used to believe, going back to Jack Kennedy in 1964 and in the 1980s when prominent Democrats Bill Bradley, Dick Gephardt and Don Rostenkowski helped to write the 1986 tax reform.

The Obama Democrats, by contrast, favor income redistribution and raising rates on the wealthy for their own partisan political sake, no matter the damage to growth, the cost in lost revenue, or a less progressive tax code as the rich exploit loopholes.

The great irony is that the candidate most likely to raise taxes on the middle class is Mr. Obama.