Krugman's broken windows

In his Feb 1 post re the "Buy American" provisions in the US stimulus bill, Paul Krugman argues that not only is fiscal demand management good policy, it is good even when it is admitted that the spending is inefficient.

Krugman makes a large concession when he grants the validity of the comparative advantage argument that's at the root of the economic consensus supporting free trade. It follows that he would have to concede that national stimulus packages which stimulate production of goods in which those nations have comparative disadvantages (i.e. have buy domestic provisions) would also be inefficient. Krugman essentially concedes that even if Doug Irwin's examples of inefficiency obtained, in other words, the need for spending now is so great it is necessary even if the same spending some time later (when domestic suppliers to government did not have a monopoly) would buy more. The need for more global stimulus is so great that apparently it would make "the world as a whole better off" even if Canada's government was using taxpayer money to develop a domestic banana industry while Singapore subsidized domestic softwood logging! Special times call for special measures... even broken windows!

For an economist, an appeal to efficiency is the trump. Yet Krugman seems to believe that trump can be trumped by an appeal to Keynesianism.

As for the empirical (evidence based, as opposed to theory/logic based) argument, perhaps Krugman will comment on the findings of the centrist Peterson Institute that "Buy American" would likely cost more jobs than it creates.