Groups of people perform acts that are subject to standards of rationality. A committee may sensibly award fellowships, or may irrationally award them in violation of its own policies. A theory of collective rationality defines collective acts that are evaluable for rationality and formulates principles for their evaluation. This book argues that a group's act is evaluable for rationality if it is the products of acts its members fully control. It also argues that such an act is collectively rational if the acts of the group's members are rational. Efficiency is a goal of collective rationality, but not a requirement, except in cases where conditions are ideal for joint action and agents have rationally prepared for joint action. The people engaged in a game of strategy form a group, and the combination of their acts yields a collective act. If their collective act is rational, it constitutes a solution to their game. A theory of collective rationality yields principles concerning solutions to games. One principle requires that a solution constitute an equilibrium among the incentives of the agents in the game. In a cooperative game some agents are coalitions of individuals, and it may be impossible for all agents to pursue all incentives. Because rationality is attainable, the appropriate equilibrium standard for cooperative games requires that agents pursue only incentives that provide sufficient reasons to act. The book's theory of collective rationality supports an attainable equilibrium-standard for solutions to cooperative games and shows that its realization follows from individuals' rational acts. By extending the theory of rationality to groups, this book reveals the characteristics that make an act evaluable for rationality and the way rationality's evaluation of an act responds to the type of control its agent exercises over the act. The book's theory of collective rationality contributes to philosophical projects such as contractarian ethics and to practical projects such as the design of social institutions.

This book contains a collection of original and state-of-the-art contributions in rational choice and general equilibrium theory. Among the topics are preferences, demand, equilibrium, core allocations, and testable restrictions. The contributing authors are Daniel McFadden, Rosa Matzkin, Emma Moreno-Garcia, Roger Lagunoff, Yakar Kannai, Myrna Wooders, James Moore, Ted Bergstrom, Luca Anderlini, Lin Zhou, Mark Bagnoli, Alexander Kovalenkov, Carlos Herves-Beloso, Michaela Topuzu, Bernard Cornet, Andreu Mas-Colell and Nicholas Yannelis.

This is a paperback edition of a major contribution to the field, first published in hard covers in 1977. The book outlines a general theory of rational behaviour consisting of individual decision theory, ethics, and game theory as its main branches. Decision theory deals with a rational pursuit of individual utility; ethics with a rational pursuit of the common interests of society; and game theory with an interaction of two or more rational individuals, each pursuing his own interests in a rational manner.

Rationality has long been a central topic in philosophy, crossing standard divisions and categories. It continues to attract much attention in published research and teaching by philosophers as well as scholars in other disciplines, including economics, psychology, and law. The Oxford Handbook of Rationality is an indispensable reference to the current state of play in this vital and interdisciplinary area of study. Twenty-two newly commissioned chapters by a roster of distinguished philosophers provide an overview of the prominent views on rationality, with each author also developing a unique and distinctive argument.

The economic crisis is also a crisis for economic theory. Most analyses of the evolution of the crisis invoke three themes, contagion, networks and trust, yet none of these play a major role in standard macroeconomic models. What is needed is a theory in which these aspects are central. The direct interaction between individuals, firms and banks does not simply produce imperfections in the functioning of the economy but is the very basis of the functioning of a modern economy. This book suggests a way of analysing the economy which takes this point of view. The economy should be considered as a complex adaptive system in which the agents constantly react to, influence and are influenced by, the other individuals in the economy. In such systems which are familiar from statistical physics and biology for example, the behaviour of the aggregate cannot be deduced from the behaviour of the average, or "representative" individual. Just as the organised activity of an ants’ nest cannot be understood from the behaviour of a "representative ant" so macroeconomic phenomena should not be assimilated to those associated with the "representative agent". This book provides examples where this can clearly be seen. The examples range from Schelling’s model of segregation, to contributions to public goods, the evolution of buyer seller relations in fish markets, to financial models based on the foraging behaviour of ants. The message of the book is that coordination rather than efficiency is the central problem in economics. How do the myriads of individual choices and decisions come to be coordinated? How does the economy or a market, "self organise" and how does this sometimes result in major upheavals, or to use the phrase from physics, "phase transitions"? The sort of system described in this book is not in equilibrium in the standard sense, it is constantly changing and moving from state to state and its very structure is always being modified. The economy is not a ship sailing on a well-defined trajectory which occasionally gets knocked off course. It is more like the slime described in the book "emergence", constantly reorganising itself so as to slide collectively in directions which are neither understood nor necessarily desired by its components.

This book is concerned with situations in which several persons reach decisions independently and the final consequence depends, potentially, upon each of the decisions taken. Such situations may be described formally by an extensive form game: a mathematical object which specifies the order in which decisions are to be taken, the information available to the decision makers at each point in time, and the consequence that results for each possible combination of decisions. A necessary requirement for rational behavior in such games is that each decision maker should reach a decision that is optimal, given his preferences over his own decisions. This requirement is far from sufficient, however, since every decision maker should in addition base his preferences upon the conjecture that his opponents will act optimally as well. It is this principle that distinguishes noncooperative game theory from one-person decision theory. The main purpose of Rationality in Extensive Form Games is to discuss different formalizations of this principle in extensive form games, such as backward induction, Nash equilibrium, forward induction and rationalizability, under the assumption that the decision makers' preferences are given by subjective expected utility functions. The various formalizations, or rationality criteria, are illustrated by examples, and the relationships among the different criteria are explored.

This book brings together the authors' joint papers from over a period of more than twenty years. The collection includes seven papers, each of which presents a novel and rigorous model in Economic Theory. All of the models are within the domain of implementation and mechanism design theories. These theories attempt to explain how incentive schemes and organizations can be designed with the goal of inducing agents to behave according to the designer's (principal's) objectives. Most of the literature assumes that agents are fully rational. In contrast, the authors inject into each model an element which conflicts with the standard notion of full rationality, demonstrating how such elements can dramatically change the mechanism design problem. Although all of the models presented in this volume touch on mechanism design issues, it is the formal modeling of bounded rationality that the authors are most interested in. A model of bounded rationality signifies a model that contains a procedural element of reasoning that is not consistent with full rationality. Rather than looking for a canonical model of bounded rationality, the articles introduce a variety of modeling devices that will capture procedural elements not previously considered, and which alter the analysis of the model. The book is a journey into the modeling of bounded rationality. It is a collection of modeling ideas rather than a general alternative theory of implementation.

When John Harsanyi came to Stanford University as a candidate for the Ph.D., I asked him why he was bothering, since it was most un likely that he had anything to learn from us. He was already a known scho lar; in addition to some papers in economics, the first two papers in this vol ume had already been published and had dazzled me by their originality and their combination of philosophical insight and technical competence. However, I am very glad I did not discourage him; whether he learned any thing worthwhile I don't know, but we all learned much from him on the foundations of the theory of games and specifically on the outcome of bar gaining. The central focus of Harsanyi's work has continued to be in the theory of games, but especially on the foundations and conceptual problems. The theory of games, properly understood, is a very broad approach to social interaction based on individually rational behavior, and it connects closely with fundamental methodological and substantive issues in social science and in ethics. An indication of the range of Harsanyi's interest in game the ory can be found in the first paper of Part B -though in fact his owncontri butions are much broader-and in the second paper the applications to the methodology of social science. The remaining papers in that section show more specifically the richness of game theory in specific applications.

This is an excerpt from the 4-volume dictionary of economics, a reference book which aims to define the subject of economics today. 1300 subject entries in the complete work cover the broad themes of economic theory. This extract concentrates on utility and probability.

In a complex and uncertain world, humans and animals make decisions under the constraints of limited knowledge, resources, and time. Yet models of rational decision making in economics, cognitive science, biology, and other fields largely ignore these real constraints and instead assume agents with perfect information and unlimited time. About forty years ago, Herbert Simon challenged this view with his notion of "bounded rationality." Today, bounded rationality has become a fashionable term used for disparate views of reasoning. This book promotes bounded rationality as the key to understanding how real people make decisions. Using the concept of an "adaptive toolbox," a repertoire of fast and frugal rules for decision making under uncertainty, it attempts to impose more order and coherence on the idea of bounded rationality. The contributors view bounded rationality neither as optimization under constraints nor as the study of people's reasoning fallacies. The strategies in the adaptive toolbox dispense with optimization and, for the most part, with calculations of probabilities and utilities. The book extends the concept of bounded rationality from cognitive tools to emotions; it analyzes social norms, imitation, and other cultural tools as rational strategies; and it shows how smart heuristics can exploit the structure of environments.