In the comments of a recent post I claimed that philosophers and economists have little sway over important social policy decisions. Discussing the subject with colleagues I was pointed to this stunning quote by Keynes:

The ideas of economists and political philosophers, both when they are right and when they are wrong, are more powerful than is commonly understood. Indeed the world is ruled by little else. Practical men, who believe themselves to be quite exempt from any intellectual influence, are usually the slaves of some defunct economist. Madmen in authority, who hear voices in the air, are distilling their frenzy from some academic scribbler of a few years back. I am sure that the power of vested interests is vastly exaggerated compared with the gradual encroachment of ideas.

I’d like to believe it but is there any empirical support? Not that I’d really want to kill such a beautiful idea with brutal facts.