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It’s really not worth spending too many pixels on Herman Cain’s 9-9-9 plan, but Dave Weigel made an interesting point about it yesterday. Cain’s plan has the kind of spiffy branding and sloganeering you might expect from a former fast food CEO, but at its core it’s nothing new: it’s just another entry in the flat-tax derby that’s been rambling along in conservative circles for the past couple of decades.

The problem, of course, is that even by Republican flat-tax standards the 9-9-9 plan is ridiculous. It would raise taxes enormously on the middle class and lower them considerably on the rich. Conservatives aren’t against that in principle, but even for them there’s a limit. A plan that nearly doubles federal taxes on an average family is just not something they can swallow. And yet, all Cain has really done is taken conservative orthodoxy and kicked it up a notch, something that’s perfectly in tune with the Tea Party zeitgeist that’s lately taken over the conservative movement. As Weigel says, “The Republican voters who love 9-9-9 believe the same things that the old Forbes [flat tax] devotees believed. They believe that other Americans are paying no net income taxes, and they don’t think it’s fair.” So how do you fight that?

Cain’s rivals have to engage in a little bit of deprogramming. They must convince voters who think that the tax code is stacked against them of the truth: That complicated code is wasting some time while saving a lot of money….So how has Cain gotten so far on this idea? “It’s a rejection of redistributionist tax policy,” says Grover Norquist, the president of Americans for Tax Reform, who is doing his gentle best to point out that 9-9-9’s a bad idea. “No one has done the calculations, so people are reacting viscerally to the idea. A single rate flat tax is a very attractive thing.” It’s attractive because it tells conservative voters what they already believe: Tax the free-loaders, simplify the forms, and the rest of the problems take care of themselves. To take Cain down, Republicans have to blow up the anti-tax arguments of 30 years.

In a sense, conservatives have finally been hoist by their own petard. Liberals have been making jokes for the past year about the otherworldy “Can You Top This?” game being played by Republican presidential candidates, each one offering up a more buffoonish idea than the next in a vain attempt to prove that they’re the purist conservative in the pack. Well, now Herman Cain has trumped them all: his 9-9-9 plan is too goofy even for the modern party to embrace, but it obeys conservative orthodoxy to a tee. So how do you convince all those people you’ve been selling conservative orthodoxy to that this, finally, is something that goes too far? Isn’t that the kind of thing a liberal would say?