Abstract

Each of the following sentences expresses a strong intuition about physical things: (a) a physical object is a three-dimensional spatial thing; (b) some physical things can, in the strict sense, remain the same thing through minor changes in their parts; (c) if x and y are physical things with the same spatiotemporal location, then x is strictly identical with y; (d) if x is a proper part of an existing physical thing and x occupies an occupiable region of space, then x is itself an existing physical thing. There is a familiar argument that purports to prove that not all of (a)--(d) can be part of our ordinary concept of a physical thing. Its strategy for defending this claim is showing that at least one of (a)--(d) must-be false. The reason it gives for concluding that (a)--(d) are inconsistent is, appropriately, that they give rise to a paradox: according to the argument, (c) commits us to identifying products of a part-loss, yet (a), (b), and (d) yield the result that the products are different things.