Morality, identity, and continuity: Reductionism about personal identity over time and utilitarianism

Date of Completion

January 2005






In Reasons and Persons and other work, Derek Parfit argues that, compared to non-reductionism, reductionism about personal identity over time provides a limited form of support for utilitarianism. Other writers have suggested that this support is more significant. In this dissertation I argue that this is not true. Parfit argues that if we become reductionists, personal identity involves less and that this is a good reason to give less weight to certain deontological constraints. Others argue that we should give such constraints no weight at all. Giving such deontological constraints less weight seems to them to make utilitarianism more plausible. ^ In Chapter 1, I argue that reductionist theories can be in competition with one another and that at least one such theory will entail that our identities are always determinate. In Chapter 2, I describe what I call the Argument from Moral Maneuverability and how it is presupposed by Parfit's arguments that reductionism supports utilitarianism. I argue that even if we do follow Parfit's lead in giving less weight to certain deontological principles, the Argument from Moral Maneuverability still fails. Rather than reductionism supporting utilitarianism, I argue that it better supports a modified form of common-sense morality. I also argue that there are forms of reductionism which can support certain deontological constraints. In Chapter 3, I extend these results to other forms of consequentialism such as rule-utilitarianism and forms of consequentialism involving lexical orderings of the good. Finally, in Chapter 4 I explore a theory of personal identity called eliminativism. I argue that this theory allows the Argument from Moral Maneuverability to succeed and thus, if true, would give some support to utilitarianism. Eliminativism, however, is a poor theory. I conclude that compared to eliminativism, reductionism actually takes away from the plausibility of utilitarianism. ^