Philosophy 2 Discussion Board

● The problem of material constitution is that the following assumptions are all plausible, but together lead to a contradiction 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 ● We have seen already in Rea’s paper two instances of the problem of material constitution, namely The Growing Argument and The Ship of Theseus Here is another: “Consider Tibbles—a cat who, at a certain time t, is endowed with a tail, but who unfortunately finds herself separated from that tail at some later time t'. (Let us suppose that Tibbles’s tail is annihilated sometime after t and shortly before t'.) The body that Tibbles has when her tail is intact we shall call ‘Body’; we will use the name ‘Body-minus’ to refer to Body minus the tail. Thus Body and Body-minus coexist, and indeed overlap, prior to the annihilation of Tibbles's tail; but clearly Body is not identical with Body-minus—Body-minus is just a proper part of Body. Now, the problem arises as follows. At t, it seems that Tibbles is identical with Body. Thus (1) At t: Tibbles = Body. At t', however, after Tibbles has suffered the annihilation of her tail, it seems that Tibbles is identical with Body-minus. Hence (2) At t': Tibbles = Body-minus. But, of course, since identity is not merely temporary, it follows from (1) and (2) that (3) (Tibbles = Body) & (Tibbles = Body-minus). And since identity is transitive, (3) entails (4) Body = Body-minus. But (4) is false. Hence something must have gone wrong.” (Rea, 537-538) ● Of course, we have seen this problem before, with Tibbles and Tib and also with Dion and Theon

The problem here might seem to arise from the following assumption, the Doctrine of Arbitrary Undetached Parts: (DAUP) Proper parts of material objects, such as Body-minus and Theon, exist even while undetached from the objects of which they are proper parts And some, like Peter van Inwagen, have tried to solve this problem by rejecting (DAUP) Rea points out that (DAUP) is, in fact, not essential to the puzzle So the puzzle does not turn on assuming that Body-minus exists; similarly, there would be a puzzle with Dion even if one did not assume Theon existed this should not be surprising because Rea maintains this puzzle we are now considering is a version of the problem of material constitution, and this problem does not involve (DAUP) ● So if the present problem is indeed a version of the problem of material constitution, the five plausible assumptions must be operative And they are: —The argument involves an Existence Assumption, there is a cat composed of particles —It involves an Essentialist Assumption, namely, where this is a body composed of particles where a body is such that it must be made up of just the things that compose it, so any addition or subtraction to it destroys that very body in other words, there is an object such that, necessarily, for all qs and t, the qs compose z at t only if z bears R1 to the qs, where R1 is defined as follows: z bears R1 to the qs =DF there is no time t such that z exists and the qs do not compose z at t. —the (PACP) is made, for one assumes the ps compose a cat, something that can gain or lost parts that is, the ps compose something that does not bear R1 to the things that compose it —The Identity Assumption is made; thus, one assumes that the cat is identical to its body

—The Necessity Assumption is made, otherwise one could assume that the cat is identical to different bodies at different times But, then, one is led to claim that the cat survived the loss of its tail (because, although, it lost some bits, this does not destroy it) and the cat did not survive the loss of its tail (because the cat was that body that has been destroyed) What Rea has recognized is that the Tibbles puzzle merely shows that there is something paradoxical about a cat losing its tail once one see this, it is obvious that the Tibbles puzzle, that is, the Body-minus Argument (and the puzzle of Dion and Theon) is really just the Growing Argument (but with shrinking rather than growing)