A Critical Exposition of Isaac Levi’s Epistemology

The branch of philosophical logic which has become known as “belief change” has, in the course of its development, become alienated from its epistemological origins. However, as formal criteria do not suffice to defend a principled choice between competing systems for belief change, we do need to take their epistemological embedding into account. Here, on the basis of a detailed examination of Isaac Levi’s epistemology, we argue for a new direction of belief change research and propose to construct systems for belief change that can do without, but do not rule out, selection functions, in order to enable an empirical assessment of the relative merits of competing belief change systems. 1. Isaac Levi’s Epistemology Isaac Levi, professor at the Columbia University of New York since 1970, puts forward his epistemological tenets in a voluminous series of publications, using a rather uncommon terminology based on logic and probability theory. Levi defends a radical new perspective on a number of traditional epistemological issues, while firmly re-establishing the bond between logic and epistemology, which has been increasingly loosening during the past forty years. Furthermore, Levi is the main pioneer and initiator of contemporary logical-philosophical research into belief change. Levi places himself explicitly within the tradition of American pragmatism. Accordingly, some of the keynotes of Levi’s epistemology can only be understood properly when placed against the background of American pragmatism. 1.1. Non-Deductive Logic and the Belief-Doubt-Belief Model In January 1872, a learned society of lawyers and scientists founded the ‘Metaphysical Club’, the cradle of American pragmatism. The philosophically concerned members of the club set out to combine the work of the