This book represents a major contribution to game theory. It offers this conception of equilibrium in games: strategic equilibrium. This conception arises from a study of expected utility decision principles, which must be revised to take account of the evidence a choice provides concerning its outcome. The argument for these principles distinguishes reasons for action from incentives, and draws on contemporary analyses of counterfactual conditionals. The book also includes a procedure for identifying strategic equilibria in ideal normal-form games. In synthesizing decision theory and game theory in a powerful way this book will be of particular interest to all philosophers concerned with decision theory and game theory as well as economists and other social scientists.

Good decisions account for risks. For example, the risk of an accident while driving in the rain makes a reasonable driver decide to slow down. While risk is a large topic in theoretical disciplines such as economics and psychology, as well as in practical disciplines such as medicine and finance, philosophy has a unique contribution to make in developing a normative theory of risk that states what risk is, and to what extent our responses to it are rational. Weirich here develops a philosophical theory of the rationality of responses to risk. He first distinguishes two types of risk: first, a chance of a bad event, and second, an act's risk in relation to its possible outcomes. He argues that this distinction has normative significance in the sense that one's attitudes towards these types of risks - and how one acts on them - are governed by different general principles of rationality. Consequently, a comprehensive account of risk must not only characterize rational responses to risk but also explain why these responses are rational. Weirich explains how, for a rational ideal agent, the expected utilities of the acts available in a decision problem explain the agent's preferences among the acts. As a result, maximizing expected utility is just following preferences among the acts. His view takes an act's expected utility, not just as a feature of a representation of preferences among acts, but also as a factor in the explanation of preferences among acts. The book's precise formulation of general standards of rationality for attitudes and for acts, and its rigorous argumentation for these standards, make it philosophical; but while mainly of interest to philosophers, its broader arguments will contribute to the conceptual foundations of studies of risk in all disciplines that study it.

Classical decision theory evaluates entire worlds, specified so as to include everything a decision-maker cares about. Thus applying decision theory requires performing computations far beyond an ordinary decision-maker's ability. In this book Paul Weirich explains how individuals can simplify and streamline their choices. He shows how different 'parts' of options (intrinsic, temporal, spatiotemporal, causal) are separable, so that we can know what difference one part makes to the value of an option, regardless of what happens in the other parts. He suggests that the primary value of options is found in basic intrinsic attitudes towards outcomes: desires, aversions, or indifferences. And using these two facts he argues that we need only compare small parts of the options we face in order to make a rational decision. This important book will interest readers in decision theory, economics, and the behavioral sciences.

Within traditional decision theory, common decision principles -- e.g. the principle to maximize utility -- generally invoke idealization; they govern ideal agents in ideal circumstances. In Realistic Decision Theory, Paul Weirch adds practicality to decision theory by formulating principles applying to nonideal agents in nonideal circumstances, such as real people coping with complex decisions. Bridging the gap between normative demands and psychological resources, Realistic Decision Theory is essential reading for theorists seeking precise normative decision principles that acknowledge the limits and difficulties of human decision-making.

An agent often does not have precise probabilities or utilities to guide resolution of a decision problem. I advance a principle of rationality for making decisions in such cases. To begin, I represent the doxastic and conative state of an agent with a set of pairs of a probability assignment and a utility assignment. Then I support a decision principle that allows any act that maximizes expected utility according to some pair of assignments in the set. Assuming that computation of an option's expected utility uses comprehensive possible outcomes that include the option's risk, no consideration supports a stricter requirement.

Food products with genetically modified (GM) ingredients are common, yet many consumers are unaware of this. When polled, consumers say that they want to know whether their food contains GM ingredients, just as many want to know whether their food is natural or organic. Informing consumers is a major motivation for labeling. Consumers who want GM-free products will pay a premium to support voluntary labeling. Labeling need not be mandatory. When polled, consumers say that they want to know whether their food contains GM ingredients, just as many want to know whether their food is natural or organic. Informing consumers is a major motivation for labeling. Why do consumers want to know about GM ingredients? GM foods are tested to ensure safety and have been on the market for more than a decade. Still, many consumers, including some with food allergies, want to be cautious. Also, GM crops may affect neighboring plants through pollen drift. Despite tests for environmental impact, some consumers may worry that GM crops will adversely effect the environment. The study of risk and its management raises questions not settled by the life sciences alone. This book surveys various labeling policies and the cases for them. It is the first comprehensive, interdisciplinary treatment of the debate about labeling genetically modified food. The contributors include philosophers, bioethicists, food and agricultural scientists, attorneys/legal scholars, and economists.

Classical decision theory evaluates entire worlds, specified so as to include everything a decision-maker cares about. Thus applying decision theory requires performing computations far beyond an ordinary decision-maker's ability. In this book Paul Weirich explains how individuals can simplify and streamline their choices. He shows how different 'parts' of options (intrinsic, temporal, spatiotemporal, causal) are separable, so that we can know what difference one part makes to the value of an option, regardless of what happens in the other parts. He suggests that the primary value of options is found in basic intrinsic attitudes towards outcomes: desires, aversions, or indifferences. And using these two facts he argues that we need only compare small parts of the options we face in order to make a rational decision. This important book will interest readers in decision theory, economics, and the behavioral sciences.

This book represents a major contribution to game theory. It offers this conception of equilibrium in games: strategic equilibrium. This conception arises from a study of expected utility decision principles, which must be revised to take account of the evidence a choice provides concerning its outcome. The argument for these principles distinguishes reasons for action from incentives, and draws on contemporary analyses of counterfactual conditionals. The book also includes a procedure for identifying strategic equilibria in ideal normal-form games. In synthesizing decision theory and game theory in a powerful way this book will be of particular interest to all philosophers concerned with decision theory and game theory as well as economists and other social scientists.

In Decision Space: Multidimensional Utility Analysis, first published in 2001, Paul Weirich increases the power and versatility of utility analysis and in the process advances decision theory. Combining traditional and novel methods of option evaluation into one systematic method of analysis, multidimensional utility analysis is a valuable tool. It provides formulations of important decision principles, such as the principle to maximize expected utility; enriches decision theory in solving recalcitrant decision problems; and provides in particular for the cases in which an expert must make a decision for a group of people. The multiple dimensions of this analysis create a decision space broad enough to accommodate all factors affecting an option's utility. The book will be of interest to advanced students and professionals working in the subject of decision theory, as well as to economists and other social scientists.

In Decision Space: Multidimensional Utility Analysis, Paul Weirich increases the power and versatility of utility analysis and in the process advances decision theory. Combining traditional and novel methods of option evaluation into one systematic method, multidimensional utility analysis is a valuable new tool. The multiple dimensions of this analysis create a decision space broad enough to accommodate all factors affecting an option's utility. The book will be of interest to advanced students and professionals working in the subject of decision theory, as well as to economists and other social scientists.

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.

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.