As part of his ongoing capitulation to the conservative movement, John McCain has sadly begun to make false claims about the revenue effects of tax cuts, as Jon Chait points out:

The old McCain called President Bush’s tax cuts fiscally and socially irresponsible, a giveaway to the rich in a time of rising inequality. The new McCain was recently interviewed by National Review’s Ramesh Ponnuru and asked if there were any circumstances, including the guarantee of spending cuts, under which he’d consider repealing the tax cuts he denounced and voted against. He replied: “No. None. None. Tax cuts, starting with Kennedy, as we all know, increase revenues.”

We all know that? In fact, economists know that this is not true. Conservative economists know this isn’t true. Even conservative economists who work in the Bush administration have admitted this isn’t true. As former Bush economist Alan Viard, now at the conservative American Enterprise Institute, said: “Federal revenue is lower today than it would have been without the tax cuts. There’s really no dispute among economists about that.”

Indeed, Bush administration economists have repeatedly stated that tax cuts don’t increase revenue since 2001.

One of those economists is Harvard’s Greg Mankiw, who bad-mouths McCain on his blog:

The interviewer, however, did not ask [McCain] the natural follow-up questions:

1. If you think the 2001 and 2003 tax cuts increased revenue, why did you vote against them?

2. If you think tax cuts increase revenue, why advocate spending restraint? Can’t we pay for new spending programs with more tax cuts?

I doubt that, in fact, Senator McCain believes we are on the wrong side of the Laffer curve. But unfortunately, fealty to the most extreme supply-side views is de rigeur in some segments of the Republican party.

But what Mankiw doesn’t mention is President Bush and Vice President Cheney’s expressed “fealty to the most extreme supply-side views,” which Mankiw conspicuously failed to change during his tenure as chair of the Council of Economic Advisers from 2003 to 2005.

Indeed, during his Senate confirmation hearing, Mankiw was asked about claims that tax cuts were self-financing, and he disavowed them, saying “I remain skeptical of those claims.” However, he also stated that he thought the administration had not made such claims, which was — and is — false:

[T]he most extreme advocates of tax cuts, I think, sometimes paint an excessively rosy picture out of what they can get out of them. I don’t think this administration has done that.

To my knowledge, Mankiw has never publicly acknowledged the truth, either during his tenure as CEA chair or in the period since.

Now that he is no longer part of the administration, will he admit that Bush and Cheney have repeatedly suggested that tax cuts increase revenue? Shouldn’t Mankiw have asked his question #2 to President Bush? What’s good for the goose is good for the gander and all that…

PS Mankiw is now advising Mitt Romney — does this mean Romney won’t make similar claims?