Gerard writes, in comments:

"The Childish Babbling of a Say...": I think it is totally appropriate to pick on the ridiculous and seemingly childish claims made by John Cochrane. But I am surprised at the lack of comment, so far, on the nonsense that John Taylor et al presented on the op-ed page of the WSJ today. The main problem with the piece is well highlighted by economists at Goldman, so I will just quote their most relevant passage.

Our second problem with the Cogan-Taylor-Wieland analysis is the absence of a serious attempt to construct a counterfactual baseline – the path the economy or some part of it would have followed in the absence of fiscal stimulus. Analytically, this is a much more serious issue than the lack of sufficient data availability, which will take care of itself. Nobody can know for sure what the baseline is, but it is incumbent on economists claiming either an effect from stimulus or the absence of one to provide some defense of the implied alternative path...

The Goldman Sachs (GS) analysis nails it. The betting among the forecasting community is that in the absence of the stimulus consumption would not have held steady in the second quarter but would have fallen significantly, and state and local government spending would not have held steady but would have fallen significantly. The absence of a counterfactual no-stimulus baseline makes the Cogan-Taylor-Wieland argument at best incoherent.

It is also simply--in context--bizarre. You plot Cogan-Taylor-Wieland's estimates of the effects of the stimulus against those of other forecasters(1):

And the Cogan-Taylor-Wieland estimate looks very strange indeed.