presentism overlap while those of PEP do not. But now we are considering a view in
which there is overlap. Why not go all the way if one is going to go partway?
Suppose the choice is between past and present existence. Which? No friend of
PEP can deny that this question deserves a principled answer. Unfortunately, I am
without principles. My inclination is to side with present existence: to have a
presently existing part suffices to be present. Intuition strongly favors that we
are presently existing, and if we persist by having temporal parts, we are presently
existing via having a presently existing temporal part. Moreover, if we deny this, we’ll
need to rethink what it even means to be present or past. (Recall that at the start of
this chapter, I said that something is present just in case some moment in its lifetime
is present, and that something is past just in case every moment of its existence is
prior to the present moment. Were these mistakes?)
Thefifth option is that sums of presently existing and pastly existing entities have a
merely deficient mode of being. On this view, although things persist through time,
nothingreallypersists through time.
None of these options is that great. This suggests that the friend of PEP should
probably reject temporal parts. There is no inconsistency in holding PEP and the
doctrine of temporal parts, but the troubling questions this conjunction raises might
make embracing both claims not worth it.
Note, however, that even if the friend of PEP rejects temporal parts, there are still
troubling questions in the neighborhood. Suppose that whenever there are some
individuals, there is a set of those individuals. Then, given PEP, there are sets whose
elements are cavemen and members of congress. In which way do these sets exist?
Suppose that there are facts, which are complex entities consisting of objects
and properties or relations.^52 My great-grandfather is merely past whereas I am
present, but there is a fact that he is my great-grandfather. In which way do facts of
this sort exist?
Note that, it is not at all obvious that mixed mereological sums, mixed sets, and
mixed facts should be treated uniformly. One might hold that sets and facts enjoy a
different kind of being than individuals since sets and facts form fundamentally
different ontological categories than those of their constituents (that are neither
sets nor facts). Meinong (1904: 85), for example, held that the mode of being of
objectives—entities that are much like facts—is not necessarily the same mode of
being as the“constituents”of the objectives; however, he was also cautious about
taking the“constituents”of objectives to be parts of objectives.
This suggests that mixed mereological sums would be the most problematic for
PEP, since there is no motivation to hold that a sum of somexs always belongs to a
different ontological category than any of thexs. One possibility is to simply deny
that there are any mereological sums of past and present objects. This is what I am
(^52) Gibson (1998: 26) briefly discusses the worry about facts or states of affairs.