The central banker's bogeyman by Ryan Avent

Then yesterday, Mr Altig (blogger at Atlanta Fed) addressed an argument made by economist Simon Wren-Lewis:

In another recent blog item (also with a pointer from Mark Thoma), Simon Wren-Lewis offers the opinion that acknowledging uncertainty about size of the output gap actually argues in favor of being "less cautious" about taking an aggressive policy course. The basic idea is familiar. It is a simple matter to raise rates should the Fed overestimate the magnitude of the output gap. But with the short-term policy rates already at zero, it is not so easy to go in the opposite direction should we underestimate the gap.

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All of recent history, in other words, suggests that Mr Wren-Lewis is exactly right: it's much easier for central banks to go in one direction than in the other. Now one could, as Mr Altig says, come up with a "plausible argument" in which things don't work like that. Given the very large and ongoing costs of labour-market weakness, I would certainly expect America's central bankers to do better than that. I would like to see some very clear evidence that a year or two of 4% inflation poses more of a threat than at least a year or two more of unemployment well above the natural rate. What we're getting instead is little more than hand-waving.