The extended self, functional constancy, and personal identity

Personal indexicals are often taken to refer to the agent of an expression’s context, but deviant uses (e.g. ‘I’m parked out back’) complicate matters. I argue that personal indexicals refer to the extended self of the agent, where the extended self is a mereological chimera incorporating whatever determines our behavioral capacities. To ascertain the persistence conditions of personal identity, I propose a method for selecting a level of description and a set of functional properties at that level that remain constant over a lifetime. I argue for functional constancy, and against continuity, as the central determinant of diachronic identity.