Krugman Leaves Me Puzzled

Paul Krugman plays a bit of inside baseball with other economists today, but of particular interest because of one baffling passage.  He's talking about the diverse views on the current crisis from conservative economists (link):

You’ve got John Taylor arguing for permanent tax cuts as a response to temporary shocks, apparently oblivious to the logical problems. You’ve got John Cochrane going all Andrew-Mellon-liquidationist on us. You’ve got Eugene Fama reinventing the long-discredited Treasury View. You’ve got Gary Becker apparently unaware that monetary policy has hit the zero lower bound.

Krugman brands these all as "non-serious arguments," which I assume means that the run of "conservative" opinion on the topic. So, why baffling? The baffling part is that nowhere on this list--nor any place else in the piece, so far as I can tell, does Krugman address what seems to me the most sensitive and perplexing issue on the agenda. That is: the multiplier--how much bang for the buck?  And what does it take to get it, and how do we know?  

There seems to me a fair amount of heat but remarkably little light in current discussions of the question.  Conservatives--this may be definitional--seem to operate on the principle that "the multiplier is one"--that every dollar emitting form the Keynesian pump is cancelled by the loss of a dollar via taxes or inflation.  A canonical formulation would be this blog entry,  which has received a fair amount of attention, not to say derision (including a bit here).  Fama's "Treasury View" piece can, I suppose, be read as kind of a variant on the "multiplier is one" argument; cf. link; link.  Krugman himself has acknowledged the issue (e.g., link).  But is remarkable how much good, general, direct analysis of the topic seems to be available out there.

The problems seem to be two, one conceptual, the other empirical.  The conceptual problem is that there seems to be nothing close to general agreement among macro theorists over how, precisely, to define the multiplier--witness the Fama/DeLong debate cited above.  The empirical difficulty seems to be that there each side seeems to be able to hoik up something in the way of numbers to support the case.

So here's an assignment for all the big brains on the econo-web: I'd love to see more of this--detached, critical, intellectually honest of the problem of the multiplier, both in concept and in practice.  And hurry up about it--that bailout money is going fast.