Looks like the Keynesians won that debate in a rout, if we compare results to previous predictions.
*Well going on 10 years later, the evidence is in: The anti-Keynesian forces have been proved conclusively mistaken on every single argument. Their refusal to pick up what amounted to a multiple-trillion-dollar bill sitting on the sidewalk is the greatest mistake of economic policy analysis since 1929 at least.
Let’s take the culprits in turn.
The contrarianism began in earnest in early 2010, when two papers were published apparently finding that austerity — increasing taxes and/or cutting spending to reduce the budget deficit — was actually beneficial. First, economists Alberto Alesina and Silvia Ardagna outlined a theory of “expansionary austerity,” arguing that governments could increase taxes, cut spending, and grow strongly. Meanwhile, economists Carmen Reinhart and Kenneth Rogoff demonstrated an apparent trigger point of a 90 percent debt-to-GDP level beyond which more borrowing would cause economic stagnation.
Both of these papers turned out to have major conceptual problems. Alesina and Ardagna basically cherry-picked their data, using unusual cases in which countries were not suffering a recession or could export their way out of problems. Reinhart and Rogoff got their causality backwards, and even had a humiliating Excel formula error that badly dented their correlation.
More clues that Alesina, Ardagna, Reinhart, and Rogoff got everything wrong can be found in the real world, where the Obama administration’s modest stimulus package, while too small to fix the Great Recession entirely, did make things much better. Conversely, the European countries that subjected themselves to severe austerity regimens saw their employment and production collapse, just like Keynes would have predicted. Greece, in particular, has suffered economic disaster considerably worse than the Great Depression in terms of output and unemployment.*