Essay Review: The Laws of Belief

Abstract

Wolfgang Spohn’s book The Laws of Belief: Ranking Theory and Its Philosophical Applications is a detailed presentation of ranking theory and its many and varied applications in philosophy. It is a work in formal or mathematical philosophy, philosophy that uses formal or mathematical tools to tackle philosophical problems. The book uses one simple and elegant yet powerful formal tool, namely, the theory of ranking functions, and applies it fruitfully to a great variety of philosophical problems. These start with problems in epistemology such as the representation of belief and its objects as well as justification and the a priori. They go to problems in metaphysics such as causation and objectification and problems in the philosophy of science such as laws and their confirmation as well as ceteris paribus conditions and dispositions. And they include, at least indirectly, problems in the philosophy of language such as conditionals and problems in the philosophy of mind such as perception and consciousness. The result is a unified picture of the world and our relation to it as epistemic agents: a philosophy. It is arrived at in a constructive attempt to reduce all “natural” or alethic modalities to nonmodal facts on the one hand and doxastic modalities as represented by ranking functions (and subjective probability measures) on the other hand. And it does so by displaying the virtues of using formal tools to tackle philosophical problems. The result is a formal philosophy whose radical nature, however, becomes visible only by working through the details, not something one can do over an extended weekend.