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Tyler Cowan: If Keynesian economic theory is so great, how come more people aren’t doing it or supporting it?

Jonathan Chait: Because the public doesn’t understand it, and politicians are too nervous to push for it.

I happen to agree with Chait, but I think there’s another issue that deserves to be called out. Cowan’s complaint, as I read it, is basically an upside-down argumentum ad populum, a.k.a., an appeal to popularity. The standard example is “My idea is valid/true/correct because many people believe in it.” They may very well believe in it, but people believe all sorts of crazy stuff for all sorts of crazy reasons, and that has no bearing on the validity of the idea itself.

Cowan takes the opposite approach—”Your idea is no good because no one supports it.” As Chait points out, there are some fairly obvious explanations for the current unpopularity of Keynesian theories. However, even absent those explanations, Cowan’s argument is bogus.