This paper challenges the influential claim that Derek Parfit’s reductionist account of personal identity supports utilitarian aggregation across persons. While reductionism undermines the idea that persons are deep metaphysical unities, it does not eliminate the moral significance of the first-person perspective or the normative force of the separateness of persons. The argument proceeds in three stages. First, it reconstructs Parfit’s Reductionist View and its role in weakening John Rawls’s separateness objection to utilitarianism. Second, it argues that metaphysical reductionism does not entail revisionism about moral justification: experiences remain perspectivally located, and justification is addressed to subjects rather than to impersonal aggregates. Third, it introduces the concept of agency collapse—harms that destroy a subject’s capacity for autonomous functioning—to show that certain forms of suffering cannot be aggregated because they eliminate the very standpoint to which aggregation would need to be justified. The paper concludes that the separateness of persons is a normative constraint independent of metaphysical debates about identity. It preserves the insights of reductionism while rejecting its aggregative implications, defending a threshold-sensitive limit on utilitarian reasoning grounded in the persistence of subjects and the structure of justificatory address.
Tommaso Biagi (Fri,) studied this question.