The nonsense that passes for Keynesian economics never ceases to amaze. It is theoretically incorrect, logically incoherent and empirically unsupported. Yet it still has adherents, presumably because they want government to play a bigger role in the economy whether it is helpful or harmful.
The greatest claim to fame for Keynesianism is the claim that it produced a recovery from the Great Depression. Unfortunately, even that period does not hold up upon inspection. A review of economic statistics from the early 1930s until post WWII shows no recovery, certainly not one which could be confused with normal economic activity. Civilian unemployment decreased because those able to fight were removed from the labor pool and sent to Europe and the Pacific. Economic activity did not recover until after the end of the war.
Dominick Armentano has a short piece on LewRockwell.com describing why the post-war recovery produces additional empirical problems for Keynesians:
Putting Government on a Diet: 1945-1950
by Dom Armentano
The recent mid-term elections were a citizen referendum for reductions in the size and scope of the federal government. But can federal spending and the budget deficit actually be reduced substantially without sending gross domestic product (GDP) into a tailspin and increasing unemployment to extraordinary levels?
Liberals and economists with Keynesian sympathies have always argued that substantial reductions in federal spending when economic activity is weak (like now) would be disastrous. Really? Let’s see what actually happened