If you change the boards of a ship one plank at a time, and replace all boards, is it the same ship?
- Ship of Theseus, described by Plutarch
- meriological: identity is sum of its parts
- Spacial Temporal Continuity: the ship moves smoothly through time. There is no point in time when you can say you have a new ship
- but what if you steal the ship piecemeal?
- the problem is unresolvable, only resolvable by using some external principle