If there’s anything we ought to have learned from the recent boom and bust, it’s that a Fed commitment to keep interest rates low for any considerable length of time, like the one Greenspan’s Fed made in 2003, is extremely unwise.

The problem isn’t simply that interest rates should be higher, or that the Fed should have a different plan for how it will adjust them in the future. It’s that the Fed shouldn’t be making promises about future interest rates at all, because it can’t predict whether a rate chosen today will be consistent with stability in six months, or in one month, or even in a week.

Instead of making promises about future interest rates, the Fed should promise to change its interest rate target whenever doing so will serve to maintain a reasonable level of nominal spending or nominal gross domestic product, which is the best way to avoid causing either a boom or a bust.