In addition to being uncertain about what the world is like, one can also be uncertain about one’s own spatial or temporal location in the world. My aim is to pose a problem arising from the interaction between these two sorts of uncertainty, solve the problem, and draw two lessons from the solution.

The non-identity problem concerns actions that affect who exists in the future. If such an action is performed, certain people will exist in the future who would not otherwise have existed: they are not identical to any of the people who would have existed if the action had not been performed. Some of these actions seem to be wrong, and they seem to be wrong in virtue of harming the very future individuals whose existence is dependent on their having been (...) performed. The problem arises when it is argued that the actions do not harm these people—because the actions do not make them worse off than they would otherwise be.1 Consider: Radioactive Waste Policy: We are trying to decide whether to adopt a permissive radioactive waste policy. This policy would be less inconvenient to us than our existing practices. If we enact the newly-proposed policy, then we will cause there to be radioactive pollution that will cause illness and suffering. However, the policy will have such significant effects on public policy and industry functioning, that different people will exist in the future depending on whether we enact the policy. Two things should be emphasized. First, the illness and suffering caused will be very serious: deformed babies, children with burns from acid rain, and adults dying young from cancer. Second, the policy will affect who will exist in the future because our present practices invade people’s everyday lives, for example by affecting recycling practices in the home; these practices will change if the policy is adopted. Furthermore, whether we adopt the policy will determine which plants are built where, what jobs are available, and what trucks are on the road. These effects will create small differences in everyone’s lives which ultimately affect who meets whom and who conceives with whom, or at least when people conceive. This affects who exists in the future. (shrink)

How should you take into account the opinions of an advisor? When you completely defer to the advisor's judgment, then you should treat the advisor as a guru. Roughly, that means you should believe what you expect she would believe, if supplied with your extra evidence. When the advisor is your own future self, the resulting principle amounts to a version of the Reflection Principle---a version amended to handle cases of information loss. When you count an advisor as an epistemic (...) peer, you should give her conclusions the same weight as your own. Denying that view---call it the ``equal weight view''---leads to absurdity: the absurdity that you could reasonably come to believe yourself to be an epistemic superior to an advisor simply by noting cases of disagreement with her, and taking it that she made most of the mistakes. Accepting the view seems to lead to another absurdity: that one should suspend judgment about everything that one's smart and well-informed friends disagree on, which means suspending judgment about almost everything interesting. But despite appearances, the equal weight view does not have this absurd consequence. Furthermore, the view can be generalized to handle cases involving not just epistemic peers, but also epistemic superiors and inferiors. (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.

Challenging, with several powerful arguments, some of our deepest beliefs about rationality, morality, and personal identity, Parfit claims that we have a false view about our own nature. It is often rational to act against our own best interersts, he argues, and most of us have moral views that are self-defeating. We often act wrongly, although we know there will be no one with serious grounds for complaint, and when we consider future generations it is very hard to avoid conclusions (...) that most of us will find very disturbing. (shrink)

I argue that standard decision theories, namely causal decision theory and evidential decision theory, both are unsatisfactory. I devise a new decision theory, from which, under certain conditions, standard game theory can be derived.

In Belief and the Will, van Fraassen employed a diachronic Dutch Book argument to support a counterintuitive principle called Reflection. There and subsequently van Fraassen has put forth Reflection as a linchpin for his views in epistemology and the philosophy of science, and for the voluntarism (first-person reports of subjective probability are undertakings of commitments) that he espouses as an alternative to descriptivism (first-person reports of subjective probability are merely self-descriptions). Christensen and others have attacked Reflection, taking it to have (...) unpalatable consequences. We prescind from the question of the cogency of diachronic Dutch Book arguments, and focus on Reflection's proper interpretation. We argue that Reflection is not as counterintuitive as it appears — that once interpreted properly the status of the counterexamples given by Christensen and others is left open. We show also that descriptivism can make sense of Reflection, while voluntarism is not especially well suited to do so. (shrink)