In his early works, Derek Parfit famously defended revisionary reductionism about personhood. According to this view, facts about personal identity consist in the holding of more particular psychological facts, which can be described wholly impersonally. He also argued that, in some cases, the truth of this view makes questions about diachronic personal identity empty questions to which no meaningful answers can be given. Yet, in his later works, Parfit defends several ethical theories such as contractualism and rule-consequentialism, which seem to (...) rely on exactly the kind of determinate notion of personal identity to which he objected earlier. Parfit, furthermore, never explored reductionism’s consequences for such theories in his later works. In order to solve this interpretative puzzle, this chapter tries to argue that, even if they are seemingly conflicting, Parfit’s views on personal identity and rule-consequentialism, Scanlonian contractualism, and Kantian contractualism do form a coherent and unified whole. (shrink)