Last week Ben Bernanke, the Federal Reserve chairman, announced a change in his institution’s recession-fighting strategies. In so doing he seemed to be responding to the arguments of critics who have said the Fed can and should be doing more. And Republicans went wild.

Now, many people on the right have long been obsessed with the notion that we’ll be facing runaway inflation any day now. The surprise was how readily Mitt Romney joined in the craziness.

So what did Mr. Bernanke announce, and why?

The Fed normally responds to a weak economy by buying short-term U.S. government debt from banks. This adds to bank reserves; the banks go out and lend more; and the economy perks up.

Unfortunately, the scale of the financial crisis, which left behind a huge overhang of consumer debt, depressed the economy so severely that the usual channels of monetary policy don’t work. The Fed can bulk up bank reserves, but the banks have little incentive to lend the money out, because short-term interest rates are near zero. So the reserves just sit there.