O racional da racionalidade

«Rationality is an a priory assumption about the way the world should work rather than a description of the way the world actually worked. The assumption that investors are rational in the long run is a useful hypothesis because it illuminates understanding of changes in prices in different markets; in the terminology of Karl Popper, it is a 'pregnant' hypothesis. Hence, it is useful to assume that investors are rational in the long run and to analyze economic issues on the basis of this assumption.»

Manias, panics and crashes, Robert Aliber e Charles Kindleberger