Objective Chance A Study in the Lewisian Tradition

Abstract: This dissertation explores the notion of objective chance as reasonable degree of belief given what might loosely be called our ultimate evidence. The goal is to develop a notion of objective chance that is broadly Humean: where chance ascriptions are construed as projected, De Dicto, physical modalities. It builds, in large part, on the work of David Lewis on objective chance and the metaphysics of indeterminism. It is argued that Lewis and the sciences take objective chance to measure the degree to which a proposition/sentence is physically determined true. These measures of determinacy are analysed in the Lewisian manner as a special kind of credence, an analysis justified by Lewis’ Principal Principle. This analysis faces several problems: the Principal Principle may not be generally applicable due to vicious circularities, chances so conceived may be incompatible with Humean supervenience, and the analysis itself may be uninformative. This dissertation addresses each of these concerns in turn. It proposes a novel trivial chance solution to the first problem and then extends this to solve the second problem, often referred to as the Bug. The aim of this text with respect to the Bug is not to provide a novel cure, but to increase our understanding of the Bug and why the standard medicine is the best on offer. Toward the end of the dissertation the informativity of the analysis is increased by an in depth study of the analysans. This study culminates in moving from Lewis’ objectified credences to credence conditional on an indexical as the analysans for objective chance.