Lewis, Perry, and what matters

Abstract

David Lewis’s attempt to reconcile the philosophical thesis that mental continuity and connectedness (the R-relation) constitute what matters in survival with the commonsense view that identity matters is fundamentally untenable. In cases of personal fission, a model of overlapping temporal parts leads to the conclusion that a person’s survival can be realized in the future of a non-identical individual. Because the R-relation can be one-many and admits of degrees, while identity is strictly one-one and all-or-nothing, the two cannot coincide as the sole object of concern in all possible cases. Consequently, the importance of personal identity is purely derivative. What truly matters is psychological continuity and connectedness, regardless of whether these relations support a claim of numerical identity. This shift from an identity-based to a relation-based concern necessitates a revision of the principles of rational egoism and self-interest. As psychological connectedness—manifested through memory and character persistence—weakens over time, the rational basis for special concern for a distant “future self” also diminishes. The fact of personal identity is not a “further fact” existing independently of physical and psychological continuities. Recognizing the reductionist nature of persons allows for a more flexible ethical framework, where the traditional boundaries of the self are viewed as less deep than commonly supposed, and the importance of survival is detached from the formal constraints of numerical identity. – AI-generated abstract.