Steven Landsburg offers one in Slate. Here’s how his argument runs:

The merits and demerits of the Huckabee tax plan are identical to the merits and demerits of a vastly liberalized IRA policy. . . . [W]hatever can be said about unlimited IRAs coupled with somewhat higher tax rates can equally be said of a national sales tax.

And many good arguments can be made in favor of unlimited IRAs. He is right about that–or at least, I think so, having argued for unlimited IRAs many times over the last few years. But all Landsburg has done is to rebut one subset of arguments against the FairTax: those that attack any type of consumption tax whatsoever.

But the plan’s critics on the Right have made three different types of argument. One is that its boosters are making wildly exaggerated claims on its behalf. A second is that a national sales tax–as opposed, say, to a flat tax on income with an exemption for savings, or an unlimited IRA–would be an administrative nightmare, creating a black market, state and local tax increases, and many other perverse consequences. A third is that it is a political fantasy that distracts conservatives from more achievable tax reforms (including liberalized IRAs). Landsburg doesn’t touch any of these extremely common criticisms of the FairTax.