Same-kind coincidence and the ship of Theseus

Abstract

Locke thought that it was impossible for there to be two things of the same kind in the same place at the same time. I offer (what looks to me like) a counterexample to that principle, involving two ships in the same place at the same time. I then consider two ways of explaining away, and one way of denying, the apparent counterexample of Locke's principle, and I argue that none is successful. I conclude that, although the case under discussion does not refute Locke's principle, it constitutes a serious challenge to it.