Decision theory is multidisciplinary and treats all aspects of choice. It is the foundation of the behavioral and social sciences. Philosophical decision theory examines and refines decision theory’s philosophical claims. Its primary subject is rational choice. Thus, it treats normative matters and is allied with branches of philosophy such as epistemology and ethics. Decision theory assists epistemology in its study of rational belief and assists ethics in its study of good acts, goals, and character traits. The behavioral and social sciences use decision theory to construct models of human behavior. Often a theory of rationality yields a good first approximation of human behavior. A general theory of rationality covers individuals and groups of people and shows how the rationality of individuals leads to the collective rationality of groups. It offers a fruitful foundation for the behavioral and social sciences. Decision theory’s main normative question concerns the nature of rationality. What principles of rationality govern choice? Principles of instrumental rationality counsel adoption of means appropriate to one’s ends. A large body of literature explicates this advice. It elaborates the view that instrumental rationality requires maximization of subjective utility: that is, acting to maximize achievement of one’s goals. An instrumentally rational act is rational conditional on the rationality of the ends the act serves and the agent’s processing of evidence about appropriate means. Other principles of rationality govern adoption of ends. Philosophical decision theory has its roots in studies of practical reasoning going back to Aristotle. It blossomed in the 20th century because of the work of Frank Ramsey, Bruno de Finetti, Leonard Savage, Richard Jeffrey, and many others. It thrives because of its intrinsic intellectual interest and because it supports traditional areas of philosophy such as epistemology and ethics. Philosophical decision theory unifies normative studies of belief, desire, and action. Its method distinguishes it from other investigations of choice. Although it draws on the behavioral and social sciences, its task is to advance foundational studies of choice rather than empirical investigations of it. Philosophy has the freedom to adopt perspectives on choice that experiments and surveys do not attempt. The normative assessment of choice is its principal exercise of this liberty. It also investigates the introspective side of choice and interpersonal comparisons of mental states, which experimentalists find insufficiently accessible to serve as the basis of public science.
Game Theory Without Partitions, and Applications to Speculation and Consensus
