Four Competing Answers

Philosophers have proposed radically different solutions. Material identity says the ship is its physical stuff — so the reassembled planks are the real ship. Functional identity says the ship is whatever keeps the same role and structure — so the repaired one in the harbor wins.

Psychological continuity says you are the connected chain of memories and personality traits linking your past to your present. Bundle theory, from David Hume, argues there is no persistent self at all — just a bundle of experiences that creates the illusion of continuity.