hold that the distinction between essence and existence in things is a merely
conceptual distinction should consider this view seriously.
But if in most (if not all) cases, the strict essence of a thing is richer in content than
its mode of being, if there is a way to reduce the notion of an essence to talk of modes
(or degrees) of being, the reduction is not straightforward. Suppose, for the sake of an
example, that sets have strict essences. Consider, for example, the singleton of
Socrates, which is strict-essentially such that Socrates is its element. The strict essence
of Singleton Socrates is an individual essence in the sense articulated earlier. The
essence of the singleton of Socrates is not the same as the essence of singleton of
Plato, yet these singletons belong to the same ontological category, and hence share
the same mode of being.
A substantially weaker notion of reduction makes use of the notion of grounding:
to reduce essence in this sense is to show that all facts about essences are grounded in
facts not about essences.^94 A successful determination of the grounds of a set of facts
does not by itself provide any sort of conceptual clarification about the notions
needed to express these facts. Maybe no such clarification is needed—and yet insofar
as we believe there are facts about strict essences, it is worth investigating whether
such facts must be grounded and, if so, what are the natures of their grounds.
Consider a traditional metaphysics of substance and attribute, according to which
(i) attributes are essentially such that they are instantiated by some substance or
other, but (ii) substances are not such that they essentially instantiate some attribute
or other.^95 Are these facts about the strict essences of the entities ungrounded facts?
My inclination is to say that they are grounded in the respective modes of being of the
entities in question. As discussed in chapter 2, substances enjoy an absolute form of
existence—their mode of being is a monadic mode. Attributes on the other hand
enjoy a polyadic form of existence—classically calledbeing-in: what it is for an
attribute to exist is for it to existina substance. Here the difference in essence is
directly reflected in the difference in how the objects exist.
Question: would it be better to say that these differences in essences are grounded
in facts about the difference of modes of being enjoyed? Or would it be better to say
that these essences are different because the relevant modes of being are among the
essences in question? In the former case, the essences are different because their
grounds are different; in the latter case, the essences are different because a complete
statement of these essences will include the modes of being of the entities in question.
Are these alternatives exclusive? That is, can the grounds of a strict essence be in
(^94) Miller (2002: 135, fn. 9) suggests that an entity’s existence is that in virtue of which it belongs to its
species and has certain properties. Were Miller to restrict these properties to those that are strictly
essential—rather thanallof that entity’s properties (Miller 2002: 167)—his view would be in line with
the views discussed here. 95
Galluzzo (2013: 340) says that Albert the Great held that accidents depend on substances (strictly)
essentially.