Must-Read: Speak for Yourself, or Why Anti-Keynesian Views Survive: "[Russ Roberts:] ‘The evidence for the Keynesian worldview is very mixed...:
...Most economists come down in favor or against it because of their prior ideological beliefs. Krugman is a Keynesian because he wants bigger government. I’m an anti-Keynesian because I want smaller government.’
Statements like this tell us rather a lot about those who make them. As statements about why people hold macroeconomic views they are wide of the mark.... The big/small government idea makes no theoretical sense. Why would wanting a larger state make someone a Keynesian? Many Keynesians, and most New Keynesians, nowadays acknowledge that monetary policy should be used to manage demand when it can. They also know that any fiscal stimulus only works, or at least works best, if it involves temporary increases in government spending. So being a Keynesian is not a very effective way of getting a larger state. It is also obviously false empirically.... Central bank models are typically Keynesian. Does that mean central banks want a larger state? No, it means the evidence suggests Keynesian economics works.
Russ Roberts says more recently:
The evidence is a mess leaving each of us free to cherry-pick what sustains our worldview be it ideological or philosophical or just consistent with our flavor of economics.
Ryan Bourne of the Institute of Economic Affairs goes further:
when the facts change, the Keynesians don’t change their minds.
To illustrate their belief that Keynesians ignore awkward facts both the authors above use the example of US growth following the 2013 sequester. (In my experience anti-Keynesians tend to shy away from data series, and especially econometrics, and prefer evidence of the ‘they said this, and it didn’t happen’ kind--particularly if ‘they’ happens to be Paul Krugman.) The problem is that this episode actually illustrates the opposite: that anti-Keynesians are so keen to grasp anything that appears to conflict with Keynesian ideas that they fail to do simple analysis and ignore others that do....
Why do we have to go over, yet again, that the clear majority of studies show that Obama’s stimulus worked? Why do we have to keep going over why UK growth in 2013 does not prove austerity works? Why do these people never mention the meta studies that confirm basic Keynesian analysis of fiscal policy? Because they want to believe that the ‘evidence is a mess’.... When anti-Keynesians tell you that support or otherwise for Keynesian macroeconomics depends on belief about the size of the state, they are telling something about where their own views come from. When they tell you everyone ignores evidence that conflicts with their views, they are telling you how they treat evidence. And the fact that some on the right take this position tells you why anti-Keynesian views continue to survive despite overwhelming evidence in favour of Keynesian theory.