Martin Peterson

This paper presents an axiomatization of the principle of maximizing expected utility that does not rely on the independence axiom or sure-thing principle. Perhaps more importantly the new axiomatization is based on an ex ante approach, instead of the standard ex post approach. An ex post approach utilizes the decision maker's preferences among risky acts for generating a utility and a probability function, whereas in the ex ante approach a set of preferences among potential outcomes are on the input side of the theory and the decision maker's preferences among risky acts on the output side

This up-to-date introduction to decision theory offers comprehensive and accessible discussions of decision-making under ignorance and risk, the foundations of utility theory, the debate over subjective and objective probability, Bayesianism, causal decision theory, game theory, and social choice theory. No mathematical skills are assumed, and all concepts and results are explained in non-technical and intuitive as well as more formal ways. There are over 100 exercises with solutions, and a glossary of key terms and concepts. An emphasis on foundational aspects of normative decision theory (rather than descriptive decision theory) makes the book particularly useful for philosophy students, but it will appeal to readers in a range of disciplines including economics, psychology, political science and computer science. • Has over 100 end of chapter review questions and exercises with solutions • Includes a chapter on how to draw a decision matrix • Explains the link between individual decision making, game theory and social choice theory Contents Preface; 1. Introduction; 2. The decision matrix; 3. Decisions under ignorance; 4. Decisions under risk; 5. Utility; 6. The mathematics of probability; 7. The philosophy of probability; 8. Why should we accept the preference axioms; 9. Causal vs. evidential decision theory; 10. Bayesian vs. non-Bayesian decision theory; 11. Game theory I: basic concepts and zero sum games; 12. Game theory II: nonzero sum and co-operative games; 13. Social choice theory; 14. Overview of descriptive decision theory; Appendix A. Glossary; Appendix B. Proof of the von Neumann-Morgenstern theorem; Further reading; Index.

Based on a modern reading of Aristotle’s theory of friendship, we argue that virtual friendship does not qualify as genuine friendship. By ‘virtual friendship’ we mean the type of friendship that exists on the internet, and seldom or never is combined with real life interaction. A ‘traditional friendship’ is, in contrast, the type of friendship that involves substantial real life interaction, and we claim that only this type can merit the label ‘genuine friendship’ and thus qualify as morally valuable. The upshot of our discussion is that virtual friendship is what Aristotle might have described as a lower and less valuable form of social exchange.

This article seeks to contribute to the discussion on the nature of choice in virtue theory. If several different actions are available to the virtuous agent, they are also likely to vary in their degree of virtue, at least in some situations. Yet, it is widely agreed that once an action is recognised as virtuous there is no higher level of virtue. In this paper we discuss how the virtue theorist could accommodate both these seemingly conflicting ideas. We discuss this issue from a modern Aristotelian perspective, as opposed to a purely exegetic one. We propose a way of resolving what seems to be a major clash between two central features of virtue ethics. Our proposal is based on the notion of parity, a concept which recently has received considerable attention in the literature on axiology. Briefly put, two alternatives are on a par (or are ‘roughly equal’) if they are comparable, although it is not the case that one is better than the other, nor that they are equally good. The advantages of applying the concept of parity to our problem are twofold. Firstly, it sheds new light on the account of choice in virtue theory. Secondly, some of the criticisms that have been mounted against the possibility of parity can be countered by considering the notion of choice from a virtue theory perspective

Some philosophers believe that two objects of value can be ‘roughly equal’, or ‘on a par’, or belong to the same ‘clump’ of value in a sense that is fundamentally different from that in which some objects are ‘better than’, ‘worse than’, or ‘equally as good as’ others. This article shows that if two objects are on a par, or belong to the same clump, then an agent accepting a few plausible premises can be exploited in a money-pump. The central premise of the argument is that value is choice-guiding. If one object is more valuable than another, then it is not permitted to choose the less valuable object; and if two objects are equally valuable it is permitted to choose either of them; and if two objects are on a par or belong to the same clump it is also permitted to choose either of them.

This article argues that, contrary to the received view, prioritarianism and egalitarianism are not jointly incompatible theories in normative ethics. By introducing a distinction between weighing and aggregating, the authors show that the seemingly conflicting intuitions underlying prioritarianism and egalitarianism are consistent. The upshot is a combined position, equality-prioritarianism, which takes both prioritarian and egalitarian considerations into account in a technically precise manner. On this view, the moral value of a distribution of well-being is a product of two factors: the sum of all individuals' priority-adjusted well-being, and a measure of the equality of the distribution in question. Some implications of equality-prioritarianism are considered.