This volume brings together a collection of papers covering a wide range of topics in computer and cognitive science. Topics included are: the foundational relevance of logic to computer science, with particular reference to tense logic, constructive logic, and Horn clause logic; logic as the theoretical underpinnings of the engineering discipline of expert systems; a discussion of the evolution of computational linguistics into functionally distinct task levels; and current issues in the implementation of speech act theory. There are contributions to current debates within cognitive science, including PDP-based models of cognition; explanation-based learning as applied to game playing strategies; and the significance of the "4-card" selection task for the mental reality of logic.