The Limits of Personal Identity

Extreme cases such as fission, duplication, and uploading have long shaped debates about personal identity. These cases are commonly taken to motivate either revisionary accounts of identity or the conclusion that identity is not what fundamentally matters. This paper argues for a different response. Rather than revising or dismissing identity, it proposes that such cases reveal a boundary of its applicability. The central claim is that identity applies only where there exists a single, ongoing, non-branching generative process underlying a person’s persistence. When this condition fails—as in cases of fission or perfect duplication—identity does not become vague, indeterminate, or unimportant. Instead, it ceases to be applicable. By distinguishing identity from roles, functional organization, and psychological continuity, the paper explains why certain extreme cases systematically resist identity-based resolution while preserving the conceptual integrity of identity within its proper domain. The result is not a revision of identity, but a clarification of the conditions under which identity claims are well-formed.