258 NONMONOTHEISTIC CONCEPTIONScomplexity theory takes to constitute being the same person) to Sam. Then
we can say what we like – that Sam 1 is identical to Sam, that Sam2 is
identical to Sam, that Sam has ceased to exist and been replaced by Sam1 and
Sam2, that Sam1 is identical to Sam on even numbered days and Sam2 is
identical to Sam on odd numbered days, or whatever. The claim is that there
would be no fact of the matter about whether Sam continues to exist if Sam
is followed by Sam1 and Sam2. What we say, if anything, in answer to Is
either Sam1 or Sam2 identical to Sam? is conventional, arbitrary or at most
pragmatic; there is no true answer.
The reply faces two problems. One is that there are contradictory answers
to the question, and the Complexity View – as we have seen – entails them.
What entails a contradiction is necessarily false. This critique is not
something that can be successfully responded to by saying, “Well, I accept
the Complexity View but when it comes to what it entails I just dismiss those
entailments that are false.” The question is not about what someone who
holds the Complexity View feels comfortable about doing, but about whether
the theory is true, and if it entails falsehoods, it isn’t true.
The other problem becomes clear when one examines the denial that
there would be a fact of the matter if Sam1 and Sam2 bear R (the alleged
person-constituting relation) to Sam. The fact is that, on the Complexity
View, there is no fact of the matter whether Sam1 and Sam2 come along or
not.
One way of seeing this is by going back to, and reflecting on, the
argument that has among its premises If I exist now, then it is logically
possible that I exist a moment from now. This argument contends that (i)
plainly, there is a fact of the matter about whether I exist now or not, and
(ii) if (i) is true then for any time there is a fact of the matter about
whether or not I exist then.
But here is another way of seeing the problem. Consider Sam and the
way things ordinarily go – Sam exists at time T and Sam exists at time T1
and no Sam1 and Sam2 crop up. If Sam-at-T is identical to – is the same
person as – Sam-at-T1, then necessarily Sam-at-T is identical to – is the
same person as – Sam-at-T1. Metaphysical identity – e.g., the numerical
identity of anything – is necessary if it obtains at all.^29
The argument for this can be put quite simply. Consider two possible
worlds W1 and W2. Deny that identity is necessary. Suppose that A, B, and
C all exist in possible worlds W1 and W2. Suppose also, as is possible if
identity is contingent rather than necessary, that in W1, A is identical to B,
and C is distinct from A and B. Suppose also, as is possible if identity is
contingent rather than necessary, that in W2 A is identical to C, and B is
distinct from A and C. If identity is contingent rather than necessary, W1
and W2 are possible as described. Now A-in-W1 is identical to A-in-W2, B-
in-W1 is identical to B-in-W2, and C-in-W1 is identical to C-in-W2. But