They've got a good point.

In 1978 Congress required the Fed to "promote effectively the goals of maximum employment, stable prices and moderate long-term interest rates."

The problem is, of course, that these goals can be inconsistent.

The Fed has begun to buy long-term Treasury obligations with printed money, hoping to force down long-term interest rate. There seems to be no sign of imminent inflation. But as economic activity picks up, all those newly printed dollars will begin flowing out of the bank accounts of the bond sellers into the hands of people who want to buy things, and that could push up prices generally.

The Fed can always reverse course. But it will be under heavy pressure not to take the punch bowl away when the party gets going. The current statute will be a weapon in the hands of the punch-drinkers.

A single-issue, stable-prices mandate would leave the Fed free to combat deflation, which can be as bad as the opposite, even by printing money if need be. For the past two years, deflation has been a serious worry.

No other central bank has an employment mandate. A stable-prices-only mandate would boost the Fed's independence and would remove any assumption that the Fed is competent to single-handedly steer the economy. It would also lower uncertainty about what the Fed is doing and why.

And lower uncertainty is always good for the economy.