The latest Bloomberg Businessweek suggests that Republican presidential candidate Herman Cain’s signature tax plan — 9 percent taxes on personal and corporate income, as well as sales — is designed to be a temporary measure.

Vows Cain at hermancain.com: “Amidst a backdrop of the economic renewal created by the 9-9-9 Plan, I will begin the process of educating the American people on the benefits of continuing the next step to the Fair Tax.”

If the “Fair Tax” is what Cain really wants, then his supporters and critics should probably be focusing more on it and less on 9-9-9. Formally known as the FairTax (one word), it isn’t perfect, but it’s conceptually sounder than 9-9-9. And it belongs to a class of tax reforms that might do more to achieve what Cain says he wants, which is simplicity, fairness, and the potential for boosting economic growth.

Of course, the FairTax has its own severe critics.