Abstract

Over the past three decades there has been a great deal of philosophical interest in puzzles about composition and identity over time. Familiar examples include the "Ship of Theseus" puzzle, the "Paradox of Increase", and the "Body-minus" puzzle. The metaphysical importance of these puzzles is hard to overemphasize; their solutions have ramifications for our views about personal identity, de re modality, the mind-body problem, and a host of other ontological issues. Surprisingly, however, no one has discussed how all of these puzzles, and their solutions, are interrelated. I argue that there is one problem underlying these puzzles. I call it the "problem of material constitution". I give, for the first time, a precise statement of this problem, I show how every solution to it is equally a solution to each of the puzzles that raise it, and I defend what I take to be its most plausible solution. ;The problem arises whenever it appears that an object a and an object b share all of the same parts and yet are essentially related to those parts in different ways. This kind of situation is paradoxical because the fact that a and b have all of the same parts suggests that a is identical with b, but the fact that they are essentially related to their parts in different ways suggests that a is distinct from b. I argue that there are only three ways to solve the problem: reject the thesis that, for any x and y, if x and y share all of the same parts then x is identical with y, reject the thesis that if x is identical with y then x is necessarily identical with y, or reject some feature of the story that raises the problem . I defend the third alternative