To be quite clear: nobody denies that common sense is good for getting out of bed, crossing the street, and for a lot of other practical purposes. However, the task is to keep it out of science. Why? Because common sense is so convincing.
There is no need to go back a few hundred years. If, in a discussion, participant A says that it is nonsense and a conspiracy of these arrogant scientists to claim that the earth moves with a tremendous speed, because he and nobody else in this room feels the slightest movement, then he has a good chance to get the assent of roughly 80 percent of an average audience (cf. Mirowski, 1995, p. 104). Participant B who tries to explain the optical illusion with the theory of relative motion has a hard time.
It is a curious fact that science is necessarily counter-intuitive: “... that the new physics of the seventeenth century, which replaced the older concepts of motion, rest, and change, involved a radical reorientation of the view of the cosmos and the possibilities of an infinite void space, thus yielding an almost entirely new philosophy of nature and a wholly different physics that contradicted ordinary intuition and common sense.” (Cohen, 1977, p. 318-319)
The problem with economics is that is has a strong and proud tradition of common sense: “... [Adam Smith] disliked whatever went beyond plain common sense. He never moved above the heads of even the dullest readers. He led them on gently, encouraging them by trivialities and homely observations, making them feel comfortable all along.” (Schumpeter, 1994, p. 185)
This tradition has a stronghold in Cambridge: “In the early thirties, he [Keynes] confessed to Roy Harrod that he was “returning to an age-long tradition of common sense”.” (Coates, 2007, p. 11)
And this explains why Keynesianism is not a science to this day (2011). Again and again, it turns out that common sense is a millstone around the neck of economics. This was already clear to Mill (!) and this is why he had no friendly word for it (2006, pp. 783, 790).
As Einstein famously put it: “... common sense is the collection of prejudices acquired by age eighteen.”
Coates, J. (2007). The Claims of Common Sense. Moore, Wittgenstein, Keynes and the Social Sciences. Cambridge, New York, etc.: Cambridge University Press.
Cohen, I. B. (1977). History and the Philosopher of Science. In F. Suppe (Ed.), The Structure of Scientific Theories, 308–349. Urbana, Chicago: University of Illinois Press.
Kakarot-Handtke, E. (2011). Why Post Keynesianism is Not Yet a Science. SSRN Working Paper Series, 1966438: 1–15. URL
Mill, J. S. (2006). A System of Logic Ratiocinative and Inductive. Being a Connected View of the Principles of Evidence and the Methods of Scientific Investigation, Vol. 8 of Collected Works of John Stuart Mill. Indianapolis: Liberty Fund.
Mirowski, P. (1995). More Heat than Light. Cambridge: Cambridge University Press.
Schumpeter, J. A. (1994). History of Economic Analysis. New York: Oxford University Press.
Related 'The bigots of common sense' and 'Economics, too, has been almost ruined by the bigots of common sense' and 'A brief history of soapbox economics' and 'Appearances and evidence' and 'Misled by ordinary intuition and common sense' and 'Marshall and the Cambridge School of plain economic gibberish' and 'First Lecture in New Economic Thinking'.