So via Kevin Drum I saw this post by Chicago School economist Tyler Cowen:
Yet Keynesian theory has a no less serious problem, namely that workers take a "stupid voluntary vacation" during the downturn, due to their stubbornness on nominal wage cuts......Aggregate demand macroeconomics works in many cases and it almost always "works" (predicts well) when the macro forces are pointed toward destructive ends. We are not sure why it works at all, or if it always works, and yet we see a great fervor of belief in it and a demonization of those who are skeptics.