Judea Pearl is an Israeli-American computer scientist and philosopher, best known for championing the probabilistic approach to artificial intelligence and the development of Bayesian networks. This book is a complete and accessible account of the theoretical foundations and computational methods that underlie plausible reasoning under uncertainty. Pearl distinguishes syntactic and semantic approaches to uncertainty and offers techniques, based on belief networks, that provide a mechanism for making semantics-based systems operational. The book will be of interest to scholars and researchers in AI, decision theory, statistics, logic, philosophy, cognitive psychology, and the management sciences. Part of the Morgan Kaufmann Series in Representation and Reasoning.