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)

Intuition—spontaneous, nondeliberative assessment—has long been indispensable in theoretical and practical philosophy alike. Recent research by psychologists and experimental philosophers has challenged our understanding of the nature and authority of moral intuitions by tracing them to “fast,” “automatic,” “button-pushing” responses of the affective system. This view of the affective system contrasts with a growing body of research in affective neuroscience which suggests that it is instead a flexible learning system that generates and updates a multidimensional evaluative landscape to guide decision and (...) action. With this latter view in mind, I revisit some of the classic hypothetical scenarios used in experimental moral psychology. (shrink)

Recently many have argued that agents must sometimes have credences that are imprecise, represented by a set of probability measures. But opponents claim that fans of imprecise credences cannot provide a decision theory that protects agents who follow it from foregoing sure money. In particular, agents with imprecise credences appear doomed to act irrationally in diachronic cases, where they are called to make decisions at earlier and later times. I respond to this claim on behalf of imprecise credence fans. Once (...) we appreciate the complexity of our intuitions about rational decision making, we can see that diachronic cases are in fact evidence for the essential claims motivating imprecise credence models. I argue that our decision theory for imprecise agents should mirror our decision theory for agents in moral dilemmas, and I develop permissive norms that explain our intuitions about both sorts of agents. (shrink)

Normativity involves two kinds of relation. On the one hand, there is the relation of being a reason for. This is a relation between a fact and an attitude. On the other hand, there are relations specified by requirements of rationality. These are relations among a person's attitudes, viewed in abstraction from the reasons for them. I ask how the normativity of rationality—the sense in which we ‘ought’ to comply with requirements of rationality—is related to the normativity of reasons—the sense (...) in which we ‘ought’ to have the attitudes what we have conclusive reason to have. The normativity of rationality is not straightforwardly that of reasons, I argue; there are no reasons to comply with rational requirements in general. First, this would lead to ‘bootstrapping’, because, contrary to the claims of John Broome, not all rational requirements have ‘wide scope’. Second, it is unclear what such reasons to be rational might be. Finally, we typically do not, and in many cases could not, treat rational requirements as reasons. Instead, I suggest, rationality is only apparently normative, and the normativity that it appears to have is that of reasons. According to this ‘Transparency Account’, rational requirements govern our responses to our beliefs about reasons. The normative ‘pressure’ that we feel, when rational requirements apply to us, derives from these beliefs: from the reasons that, as it seems to us, we have. (shrink)

Should we be time-biased on behalf of other people? 'Sometimes yes, sometimes no'—it is tempting to answer. But this is not right. On pain of irrationality, we cannot be too selective about when we are time-biased on behalf of other people.

Most of us display a bias toward the near: we prefer pleasurable experiences to be in our near future and painful experiences to be in our distant future. We also display a bias toward the future: we prefer pleasurable experiences to be in our future and painful experiences to be in our past. While philosophers have tended to think that near bias is a rational defect, almost no one finds future bias objectionable. In this essay, we argue that this hybrid (...) position is untenable. We conclude that those who reject near bias should instead endorse complete temporal neutrality. (shrink)

Most of us are “time-biased” in preferring pains to be past rather than future and pleasures to be future rather than past. However, it turns out that if you are risk averse and time-biased, then you can be turned into a “pain pump”—in order to insure yourself against misfortune, you will take a series of pills which leaves you with more pain and better off in no respect. Since this vulnerability seems rationally impermissible, while time-bias and risk aversion seem rationally (...) permissible, we are left with a puzzle. (shrink)

Contemporary philosophers interested in value theory appear to be largely concerned with questions of the following sort:What is value?What is the meaning of the word ‘good’?Does the attribution of value to an object have a cognitive, or merely an emotive, significance?The first question is metaphysical; to ask it is analogous to asking in physics:What is matter?What is electricity?The others are generally treated as semantical questions; to ask them is analogous to asking in statistics:What is the meaning of the word ‘probable’?Does (...) an attribution of probability express an objective fact, or merely a subjective attitude? (shrink)

I consider the implications of incommensurability for the assumption, in rational choice theory, that a rational agent’s preferences are complete. I argue that, contrary to appearances, the completeness assumption and the existence of incommensurability are compatible. Indeed, reflection on incommensurability suggests that one’s preferences should be complete over even the incommensurable alternatives one faces.