Social and Natural Sciences

I believe that it reflects a misunderstanding not so much of the character and possibilities of social science as of the character and possibilities of natural science. In both, there is no “certain” substantive knowledge; only tentative hypotheses that can never be “proved”, but can only fail to be rejected, hypotheses in which we may have more or less confidence, depending on such features as the breadth of experience they encompass relative to their own complexity and relative to alternative hypotheses, and the number of occasions on which they have escaped possible rejection. In both social and natural sciences, the body of positive knowledge grows by the failure of a tentative hypothesis to predict phenomena the hypothesis professes to explain; by the patching up of that hypothesis until someone suggests a new hypothesis that more elegantly or simply embodies the troublesome phenomena, and so on ad infinitum.

Nobel Memorial Lecture by Milton Friedman, 13/12/1976