I advocate Time-Slice Rationality, the thesis that the relationship between two time-slices of the same person is not importantly different, for purposes of rational evaluation, from the relationship between time-slices of distinct persons. The locus of rationality, so to speak, is the time-slice rather than the temporally extended agent. This claim is motivated by consideration of puzzle cases for personal identity over time and by a very moderate form of internalism about rationality. Time-Slice Rationality conflicts with two proposed principles of (...) rationality, Conditionalization and Reflection. Conditionalization is a diachronic norm saying how your current degrees of belief should fit with your old ones, while Reflection is a norm enjoining you to defer to the degrees of belief that you expect to have in the future. But they are independently problematic and should be replaced by improved, time-slice-centric principles. Conditionalization should be replaced by a synchronic norm saying what degrees of belief you ought to have given your current evidence and Reflection should be replaced by a norm which instructs you to defer to the degrees of belief of agents you take to be experts. These replacement principles do all the work that the old principles were supposed to do while avoiding their problems. In this way, Time-Slice Rationality puts the theory of rationality on firmer foundations and yields better norms than alternative, non-time-slice-centric approaches. (shrink)

An examination of topics involved in statistical reasoning with imprecise probabilities. The book discusses assessment and elicitation, extensions, envelopes and decisions, the importance of imprecision, conditional previsions and coherent statistical models.

Ranging over central issues of morals and politics and the nature of freedom and authority, this study examines the role of value-neutrality, rights, equality, ...

Diachronic Dutch book arguments seem to support both conditionalization and Bas van Fraassen's Reflection principle. But the Reflection principle is vulnerable to numerous counterexamples. This essay addresses two questions: first, under what circumstances should an agent obey Reflection, and second, should the counterexamples to Reflection make us doubt the Dutch book for conditionalization? In response to the first question, this essay formulates a new "Qualified Reflection" principle, which states that an agent should obey Reflection only if he or she is (...) certain that he or she will conditionalize on veridical evidence in the future. Qualified Reflection follows from the probability calculus together with a few idealizing assumptions. The essay then formulates a "Distorted Reflection" principle that approximates Reflection even in cases where the agent is not quite certain that he or she will conditionalize on veridical evidence. In response to the second question, the essay argues that contrary to a common misconception, not all Dutch books dramatize incoherence—some dramatize a less blameworthy sort of epistemic frailty that the essay calls "self-doubt." The distinction between Dutch books that dramatize incoherence and those that dramatize self-doubt cross-cuts the distinction between synchronic and diachronic Dutch books. The essay explains why the Dutch book for conditionalization reveals true incoherence, whereas the Dutch book for Reflection reveals only self-doubt. (shrink)

Is Bayesian decision theory a panacea for many of the problems in epistemology and the philosophy of science, or is it philosophical snake-oil? For years a debate had been waged amongst specialists regarding the import and legitimacy of this body of theory. Mark Kaplan had written the first accessible and non-technical book to address this controversy. Introducing a new variant on Bayesian decision theory the author offers a compelling case that, while no panacea, decision theory does in fact have the (...) most profound consequences for the way in which philosophers think about inquiry, criticism and rational belief. The new variant on Bayesian theory is presented in such a way that a non-specialist will be able to understand it. The book also offers new solutions to some classic paradoxes. It focuses on the intuitive motivations of the Bayesian approach to epistemology and addresses the philosophical worries to which it has given rise. (shrink)

A critical examination of the Reflection principle in Bayesian epistemology, and of the diachronic Dutch-book-style arguments that have been invoked to support Reflection and Conditionalization.

We are purposive agents; but we—adult humans in a broadly modern world—are more than that. We are reflective about our motivation. We form prior plans and policies that organize our activity over time. And we see ourselves as agents who persist over time and who begin, develop, and then complete temporally extended activities and projects. Any reasonably complete theory of human action will need in some way to advert to this trio of features—to our reflectiveness, our planfulness, and our conception (...) of our agency as temporally extended. These are, further, features that have great significance for the kinds of lives we can live. For these two reasons I will say that these are among the core features of human agency. A theory of human action needs to say what these core features consist in and how they are related to each other. And such a theory needs also to clarify the relation between these core features of our agency and the possibility that we are fully embedded in an event causal order. (shrink)

the symmetry of our evidential situation. If our confidence is best modeled by a standard probability function this means that we are to distribute our subjective probability or credence sharply and evenly over possibilities among which our evidence does not discriminate. Once thought to be the central principle of probabilistic reasoning by great..

Philosophical orthodoxy identifies weakness of will with akrasia: the weak willed person is someone who intentionally acts against their better judgement. It is argued that this is a mistake. Weakness of will consists in a quite different failing, namely an over-ready revision of one's intentions. Building on the work of Bratman, an account of such over-ready revision is given. A number of examples are then adduced showing how weakness of will, so understood, differs from akrasia.

Decisions are made under uncertainty when there are distinct outcomes of a given action, and one is uncertain to which the act will lead. Decisions are made under indeterminacy when there are distinct outcomes of a given action, and it is indeterminate to which the act will lead. This paper develops a theory of (synchronic and diachronic) decision-making under indeterminacy that portrays the rational response to such situations as inconstant. Rational agents have to capriciously and randomly choose how to resolve (...) the indeterminacy relevant to a given choice-situation, but such capricious choices once made constrain how they will choose in the future. The account is illustrated by the case of self-interested action in situations where it is indeterminate whether you yourself will survive to benefit or suffer the consequences. The conclusion emphasizes some distinctive anti-hedging predictions of the account. (shrink)

The Eternal Coin is a fair coin has existed forever, and will exist forever, in a region causally isolated from you. It is tossed every day. How confident should you be that the Coin lands heads today, conditional on (i) the hypothesis that it has landed Heads on every past day, or (ii) the hypothesis that it will land Heads on every future day? I argue for the extremely counterintuitive claim that the correct answer to both questions is 1.

The incomparability of alternatives is thought to pose a problem for justified choice, particularly for proponents of comparativism better than,worse than,equally good,roughly equalon a par. namely, rejection of the transitivity of the relation In this paper, I argue that proponents of comparativism need not incur this cost. I defend the possibility of justified choice between incomparable alternatives on grounds that comparativists can accept. The possibility of incomparability has been met with resistance, in part because of the intuitive appeal of comparativism. (...) By defending the possibility of justified choice between incomparable alternatives on grounds that comparativists can accept, this paper supports further inquiry into the subject of incomparability. (shrink)

Bayesians often confuse insistence that probability judgment ought to be indeterminate (which is incompatible with Bayesian ideals) with recognition of the presence of imprecision in the determination or measurement of personal probabilities (which is compatible with these ideals). The confusion is discussed and illustrated by remarks in a recent essay by R. C. Jeffrey.

in The Oxford Handbook of Corporate Social Responsibility, ed. Paul Anand, Prasanta Pattanaik, and Clemens Puppe, forthcoming 2007.

(No abstract is available for this citation).

This is a major contribution to the theory of rational choice which will be of particular interest to philosophers and economists. The author sets out the foundations of rational choice, and then sketches a dynamic choice framework in which principles of ordering and independence follow from a number of apparently plausible conditions. However, there is potential conflict among these conditions, and when they are weakened to avoid it the usual foundations of rational choice no longer prevail. The thrust of the (...) argument is to suggest that the theory of rational choice is less deterministic than many suppose. (shrink)

The incomparability of alternatives is thought to pose a problem for justified choice, particularly for proponents ofcomparativism– the view that comparative facts about alternatives determine what one rationally ought to choose. As a solution, it has been argued that alternatives judged incomparable by one of the three standard comparative relations, “better than,” “worse than,” and “equally good,” are comparable by some fourth relation, such as “roughly equal” or “on a par.” This solution, however, comes at what many would regard as (...) too high a cost – namely, rejection of the transitivity of the relation “at least as good as.” In this paper, I argue that proponents of comparativism need not incur this cost. I defend the possibility of justified choice between incomparable alternatives on grounds that comparativists can accept. The possibility of incomparability has been met with resistance, in part because of the intuitive appeal of comparativism. By defending the possibility of justified choice between incomparable alternatives on grounds that comparativists can accept, this paper supports further inquiry into the subject of incomparability. (shrink)

Many have claimed that unspecific evidence sometimes demands unsharp, indeterminate, imprecise, vague, or interval-valued probabilities. Against this, a variant of the diachronic Dutch Book argument shows that perfectly rational agents always have perfectly sharp probabilities.

Many economic problems are also ethical problems: should we value economic equality? how much should we care about preserving the environment? how should medical resources be divided between saving life and enhancing life? This book examines some of the practical issues that lie between economics and ethics, and shows how utility theory can contribute to ethics. John Broome's work has, unusually, combined sophisticated economic and philosophical expertise, and Ethics Out of Economics brings together some of his most important essays, augmented (...) with an updated introduction. The first group of essays deals with the relation between preference and value, the second with various questions about the formal structure of good, and the concluding section with the value of life. This work is of interest and importance for both economists and philosophers, and shows powerfully how economic methods can contribute to moral philosophy. (shrink)

Empirical findings suggest that temptation causes agents not only to change their desires, but also to revise their beliefs, in ways that are not necessarily irrational. But if this is so, how can it be rational to maintain a resolution to resist? For in maintaining a resolution it appears that one will be acting against what one now believes to be best. This paper proposes a two-tier account according to which it can be rational neither to reconsider the question of (...) what one is going to do nor the question of what it is best to do; hence in the resolute agent the change in belief is not actual but merely potential. Various reasons are given for thinking that the resulting account is preferable to an alternative given by Bratman. (shrink)