Reasoning and decision making are fundamental parts of the knowledge representation and reasoning (KR&R) artificial intelligence (AI) approach. Research on the two topics of reasoning and decision making is often done in isolation, with different methods and different theoretical understandings for the two topics. The chapter distinguishes research along representation lines, taking particular aim at logic-based and probability-based representations. Research on representation languages that permit tractable query answering yielded specialized languages with large bodies of applications. The chapter describes work along these research paths, focusing on logical reasoning, probabilistic reasoning, and commonsense reasoning. Decision making as a research area spans the disciplines of economics, psychology, computer science, and virtually all the engineering disciplines. The chapter looks at approaches to autonomous decision making developed over the past fifty years. Research on commonsense reasoning is divided into three main streams: logical theory, large commonsense knowledge bases, and ad hoc commonsense reasoning techniques.

To illustrate the explanatory potential of cognitive maps, this chapter deploys them against a venerable philosophical argument for languageless thought and reasoning. The explanation shows that we can accommodate Chrysippus' dog without assimilating animal minds to human minds. The chapter illustrates the explanatory resources of an intermediate position that countenances non-linguistic cognition while sharply distinguishing it from linguistic cognition. It focuses on two crucial features of human propositional attitudes: they have logical form, and they participate in deductive reasoning sensitive to that form. Discussions of Chrysippus' dog typically choose among four strategies: (1) Treat the dog as executing a deductive inference; (2) Attribute logical reasoning to the dog, but construe the attribution instrumentally; (3) Do not attribute logical reasoning to the dog; and (4) Grant that the dog records no additional relevant observations beyond those mentioned by Chrysippus. The chapter presents a Bayesian-cum-cartographic model of Chrysippus' dog.

This chapter presents the concrete form and full range of Immanuel Kant's critique of Francis Hutcheson. The trajectory of Kant's philosophy as expressed in his own writings must itself serve to explain why Kant himself, despite his repeated criticisms of Hutcheson, could still describe the basis of ethical consciousness as a sensus moralis, and that at a time when he had already discovered the formula of the Categorical Imperative. Kant's criticisms were directed exclusively against the specific form that the consequences of the theory of moral sense had assumed. Hutcheson shared Kant's conviction concerning the categorical character of moral obligation, and the concept of 'moral sense' clearly posed and revealed the problem of providing a satisfactory theoretical grounding for moral philosophy. Hutcheson had demonstrated the absolute impossibility of deriving the idea of 'the good' in terms of hypothetical or deductive logical reasoning.