In contemporary circles, a common complaint against possibilism is that actuality
and existence are coextensive as a matter of conceptual necessity.^63 Is this correct?
Ontologies that recognize the existence of merely possible objects existed well before
the birth of David Lewis. The question of the reality of the merely possible has been a
thorny one for many centuries, and philosophers such as Scotus, Suárez, and
Descartes are each plausibly interpreted as recognizing an ontology that includes
merely possible beings as well as actual ones.^64 But none held that the way in which
the possibles are real is the same as the way in which actual objects are real.^65 By the
time the twentieth century is well on its way, wefind the metaphysician Jared Sparks
Moore (1927: 94–5) confidently claiming that to assert that something is actual is
certainlymore than to assert that something is real or that it is. Perhaps each of these
philosophers is conceptually confused. But I think not.
Let’s examine some ways for a possibilist to be an ontological pluralist. There are at
least two different possibilist views on which existence is systematically variably
axiomatic, at least given one further assumption. This assumption is that there can
be a second-order logic that permits quantification into the predicate position, and
this second-order logic is properly thought of aslogic. Perhaps this assumption is
ultimately dispensable to the arguments we’ll soon explore—I suspect that it is—but
it is certainly convenient to make when stating the views in question. Let’s now turn
to the views.
Thefirst view is a Bricker-style possibilism according to which possible objects can
have exactly the same properties as actual objects, and moreover have them in exactly
the same way as actual objects. On Bricker’s (2001) view, every actual object has at
least one merely possible duplicate. For example, there is a merely possible individual
who is a duplicate of me, and hence is a person, is made offlesh and blood, and has
sorrows and joys. (I hope his book isfinished on time!)
There are two ways to develop a Bricker-inspired possibilist version of ontological
pluralism.^66 The choice point is whether to take one mode of being to encompass both
the possible and the actual whilst a second encompasses merely the actual, or rather to
plump for a view on which these two modes of being do not overlap at all.^67 Let’s
consider a version that takes thefirst option: there is an outer-domain quantifier that
includes the merely possible as well as the actual, and an inner-domain quantifier
that includes only the actual. On this kind of possibilism, existence is systematically
(^63) Lewis (1986: 97–101) eloquently states and responds to this complaint. Gibson (1998: 2) and Miller
(2002: 82) claim that 64 “actual”and“exists”are synonyms. They are not.
On Scotus, see King (2001); on Suárez, see Coffey (1938: 44) and Doyle (1967); on Descartes, see
Brown (2011) and Cunning (2014). Additionally, McDermott (1969: 6–10) reconstructs the logical system
of the Buddhist philosopher Ratnak 65 īrti as one employing quantification over possible individuals.
66 Gilson (1952: 3) says that thefirst division of being is between the actual and the merely possible.
Also worth considering is the view defended by Solomyak (2013), according to which the two modes
of being correspond to two different ways of bearing properties or saturating facts. I’ll have more to say
about this sort of view in section 3.7. 67
Bricker (2001, 2006) unsurprisingly faces a similar choice.