Philosophy 2 Discussion Board

● Rea begins by noting that there are “various puzzles that set our intuitions about composition and identity against one another” a material object is something that is made out of matter, where this is just stuff that takes up space examples of material objects are desks, trees, human bodies, brains, apples a composes b when, in some sense, a makes up b or a provides the matter of b a and b are identical when a/b is the same thing ● Here are some of these puzzles: (1) the Growing Argument, aka the Paradox of Increase (2) the Ship of Theseus (3) the Body-minus Argument, aka the Puzzle of Tibbles the cat (consider also Dion and Theon) (4) the Puzzle of the Statue and the Clay, aka Lumpl and Goliath Rea contends that there is one problem underlying all these different puzzles this is the problem of material constitution every solution to this problem solves all four puzzles (though not vice versa) these puzzles are usually treated in isolation of each other; this is a mistake or, at least, inefficient, if there is really only a single puzzle here ● There are five individually plausible and jointly incompatible assumptions underlying each of the puzzles under consideration problem of material constitution is just that these five assumptions are both plausible and incompatible ● Here is some needed terminology: —‘the ps’ is a plural variable, a term of collective reference that refers neither to the set containing the ps, nor to any object whose parts are the ps the ps are not a thing, they are just a bunch of things e.g. the things in my pocket; the people presently living in California; what’s on my desk —‘the ps’ in the expression ‘the ps compose x’ refers collectively to all of the ps, whatever they are, that together compose the object x

‘the ps compose x’ is an abbreviation for ‘the ps are all parts of x and no two ps overlap and every part of x overlaps at least one of the ps’ —if the ps compose x and the ps compose y, then x constitutes y note that constitution is symmetric, so if aRb, then bRa —in the following, F is a schematic letter that takes as substitution instances (kind) nouns such as ‘human being’, ‘ship’, ‘cat’, ‘statue’ and so on —in the following, R is a schematic letter that takes as substitution instances relations such as ‘is at all times composed by’, ‘is at all times composes by some proportion of’ and so on ● the problem of material constitution arises whenever it appears that an object a and an object b constitute one another and yet are essentially related to their parts in different ways this is problematic because it seems one can account for the relevant appearance only be denying that what appears to be correct is indeed correct or by sacrificing some intuition about composition or identity at the core of the problem are five assumptions: The Existence Assumption (i) there is an F and there are ps that compose it The Essentialist Assumption (ii) if the ps compose an F, then they compose an object that is essentially such that it bears a certain relation R to its parts The Principle of Alternative Compositional Possibilities (PACP) (iii) if the ps compose an F, then they compose an object that can exist and not bear R to its parts The Identity Assumption (iv) if the ps compose both a and b, then a is identical with b The Necessity Assumption (v) if a is identical with b then a is necessarily identical with b ● Here is an argument that these five assumptions are incompatible, that they lead to a contradiction (1) S is an F and the ps compose S at t. (Instantiation of Existence Assm.) (2) There is a z1 such that the ps compose z1 at t and, necessarily, for all qs and t, the qs compose z1 at t only if z1 bears R to the qs. (From 1, Essentialist Assm.)

(3) There is a z2 such that the ps compose z2 at t and, possibly, there are qs and t such that the qs compose z2 at t and z2 does not bear R to the qs. (From 1, PACP) (4) The ps compose Z1 at t and, necessarily, for all qs and t, the qs compose Z1 at t only if Z1 bears R to the qs. (Instantiation of 2) (5) The ps compose Z2 at t and, possibly, there are qs and t such that the qs compose Z2 at t and Z2 does not bear R to the qs. (Instantiation of 3) (6) Z1 = Z2 (From Identity Assm., 4, 5) (7) Possibly, Z1 exists or Z2 exists and Z1 ≠ Z2. (From 4, 5) (8) Z1 ≠ Z2. (From 7, Necessity Assm.) ** Contradiction (6, 8)