depends on kind G”is possible. For now, I won’t settle the question of to which
ontological category ontological categories belong, or whether ontological categories
are even entities at all.^21
Westerhoff points out two problems with understanding ontological categories as
the most general kinds, properties, or classes of things. Thefirst problem is that some
ontological categories can contain other ontological categories (2005: 22). For
example, consider the following putative system of categories:entity, which has as
subcategoriesparticularanduniversal;particularhas as subcategoriessubstanceand
event; whileuniversalhas as subcategoriesphysicalandimmaterial. On this scheme,
entity,particular, andsubstanceare ontological categories, and yet onlyentityis the
most general category, since it includesparticular, which in turn includessubstance.
Were there to be no entities, there would be no particulars or universals. This account
of ontological categories as maximally general kinds guarantees that there must be
exactly one ontological category, namelyentity, or, at the very least, that every
ontological category contains every being.^22 This is a result that few of those who
employ the expression“ontological category”will appreciate.
It is not obvious that there is a unique“highest”ontological category.^23 Recall the
Aristotelian slogan that“being is not a genus,”and the ontological systems that it
inspired. An implication of the claim that being is not a genus is that there is no
unique“highest”ontological category. Does not the author of theCategoriesdeserve
better treatment than to have his system of ontological categories ruled out byfiat?
Do we want an account of ontological categories on which they cannot be nested and
there is a single“highest”ontological category such asentity? It might be true as a
matter of metaphysics that there is a highest ontological category. But insofar as we
care about neutrality, we do not want this to be true as a matter of definition.^24
Although neutrality is not a methodological priority for me, on my preferred
metaphysics,entityis not an ontological category. I do not think it is true as a matter
of metaphysics that there is a highest ontological category. (More on this in section
4.6 and chapter 5.)
The second problem raised by Westerhoff is thatgeneralityis cheap. Consider the
class of elephants and the class of musical instruments, classes that have very little in
common with each other. The class that is the union of these two classes is more
general than either. One can always generate more general classes by disjoining more
specific ones. For example, the class of universals and substances is more general than
(^21) Lowe (2006: 6–7) denies that ontological categories are themselves entities.
(^22) Joshua Spencer has pointed out to me one system of categories and an attendant metaphysical system
in which there are multiple categories but all are coextensive withentity. Suppose thatentity,actual entity,
andpossible entityare each ontological categories, but every possible entity is actualized. Then the three
categories completely overlap. 23
It is surprising that Westerhoff (2005) does not note this, since he clearly indicates in thefirst chapter
of his book that many ontological systems do not have a topmost category. Rather, he focuses on the
problems generated by the fact that categories can be nested. 24
Van Inwagen (2014: 198) is neutral on whetherentityis an ontological category.