Humans are uniquely good at inventing norms, thinking about norms, complying with norms and defeating norms. It is small wonder, then, that norms are a focus of much interest as well as debate across the cognitive sciences, encompassing such diverse issues as rationality, morality and action. The aim of the present symposium is to bring together a range of psychological and philosophical contributions to this pertinent debate. Contributors come from diverse backgrounds, including epistemology, meta-ethics, moral judgment, decision making, and reasoning. We will examine foundational issues in normative thinking, such as: What is the relation between norms and descriptions? What are the psychological mechanisms underlying normative thinking? How do epistemic and moral norms guide action? What, if any, are the appropriate norms for knowledge, rationality, and moral behaviour, and how can they be determined?