Popper and the non-Bayesian tradition: Comments on Richard Jeffrey

Abstract

My first serious encounter with Popper's work occurred after several years of graduate work in philosophy which in turn had been preceeded by several years of graduate work in physics. Like many scientists who read Popper, including such notables as Herman Bondi and John Eccles, I found that many of Popper's views harmonized well with my previous scientific experience. In fact, so favorable was my impression of his work that I began a dissertation on Popper's Philosophy of Science. I soon found, however, that the arguments Popper offered for those intuitively appealing views did not measure up to my newly acquired philosophical standards. Moreover, it also became clear that Popper had misunder stood, or at least misrepresented, his opponents, especially Carnap. Indeed, the misrepresentation often seemed so great as to be perverse, even willful. I abandoned the proposed dissertation on Popper. The point of these autobiographical remarks is to show the basis of my personal sympathy with Professor Jeffrey's feelings of frustration in dealing with Popper and his followers. Moreover, I wish to indicate my approval of his attempt to make clear in public how some of these feelings were generated. Nevertheless, while I reject the details of most of Popper's views and would not employ his arguments, much less his mode of argumentation, there is a serious sense in which I think that Popper's general position must be defended against the arguments in the latter parts of Jeffrey's paper. This is because Popper represents an important tradition in epistemological thought. Indeed, this tradition constitutes the major alternative to the tradition now represented by a Bayesian verifica tionism of the sort Jeffrey advocates. In what follows, therefore, I will first indicate some major components of the two traditions, one Bayesian, one non-Bayesian. It will be clear, I think, why Jeffrey and Popper are on opposing sides. Having distinguished the two traditions, I will then at tempt to show that the general Popperian insights which Jeffrey recasts