is always the sum of the masses of its parts.) That said, as noted in section 2.2, I think
that all determinates of a given determinable are equally natural and as natural as the
determinable itself. So if the mass property enjoyed by a person is a determinate of
the same determinable as the mass property enjoyed by, for example, a fundamental
particle, then that person is fully real if that mass property enjoyed by that funda-
mental particle is fully real. So, for me, the issue is whether the mass property enjoyed
by a composite object really is a determinate of the same determinable as that enjoyed
by a fundamental particle. I don’t know how one goes about settling this. (Does the
fact that it makes good sense to assign numbers to quantities of mass and perform
algebraic operations on those numbers settle the issue?) Similar remarks apply to
other putatively fundamental properties postulated by physics. Persons have a net-
charge in virtue of having parts that enjoy various charges. Is the net-charge of a
person a determinate of the same determinable as the charge of one of the electrons
that are among her parts?
Net-charge and net-mass are good candidates for being perfectly natural properties,
and, moreover, holes cannot enjoy such properties, unlike shape. This is good, since it
is a constraint on my project that any argument for the full reality of persons not
generalize to an argument for the full reality of holes. However, arbitrary undetached
parts and mere aggregates of material objects also enjoy net-charge and net-mass. I am
more willing to accept the full reality of these things than I am of holes. But that this
argument would generalize to cover arbitrary objects does give me pause.
What about causation, or power, or some other notion of efficacy? Trenton Merricks
(2003) endorses a metaphysics on which all composite objects have non-redundant
causal powers. He argues that alleged composites such as baseballs do not enjoy novel
causal powers over and above those enjoyed by their parts and hence do not exist. But
on Merricks’s view, persons do enjoy novel causal powers. Now although thefunda-
mentalontology Ifind attractive is similar to Merricks’s metaphysic in that the only
material things that arefullyreal are persons and the objects of successful scientific
discourse (which would include the objects of biology), I do not follow Merricks in
eliminatingthings such as baseball bats or cars. Although perhaps they are not fully real,
they do enjoy some degree of reality. Still, maybe we can use Merricks’sappealtonovel
causal powers as a way to argue for the full reality of people.
My inclination is that causal powers are not perfectly natural, and that things
do not have causal powers independently of the properties that they enjoy. So if
a person has causal powers that are not had in virtue of the powers of her parts,
it must be because the person has properties that are genuinely novel, i.e., are
intrinsic properties that do not supervene on the perfectly natural properties
or relations of her parts. And it is these novel properties that underwrite
any novel causal powers that the persons might enjoy.^28 Forthisreason,in
(^28) Compare with Merricks (2003: 93–117).