George Wade
Università della Svizzera italiana
How are objects located in spacetime? A popular answer is identity supersubstantivalism, the notion that objects are numerically identical to regions at which they are located (Calosi and Duerr 2022). This paper provides a novel argument showing that a world where identity supersubstantivalism holds cannot be gunky i.e., must contain atomic objects (Varzi 2016). Gunk, however, is widely defended; it certainly seems to be conceivable (Sider 1993), may be actual (Arntzenius 2003), and appears necessary if we wish to make sense of the notion of perfect contact between objects (Zimmerman 1996). Thus, this incompatibility constitutes a significant blow to the friend of identity supersubstantivalism.
Briefly, the argument proceeds as follows. For an arbitrary gunky object, X, and given mereological universalism, a standard assumption of Classical Extensional Mereology, I show that there is some procedure by which we can select two parts of X – call these A and B – such that A and B can be found at every subregion of X’s location. Thus, X is an object known as a ‘Stoic blend’ (so-called due to their discovery by the Stoic thinker Chrysippus (Nolan 2006)). Stoic blends, however, can be shown to violate one of the following two mereological principles – either (Exactness) or (No Colocation) – both of which are entailed by identity supersubstantivalism:
– (Exactness): every object X must be exactly located at a region, R, which is the case iff R has the same shape, and stands in all the same spatiotemporal relations, as X (Parsons 2007).
– (No Colocation): no two objects can share the same exact location.
Since X was chosen arbitrarily, we can assume that every gunky object must violate one of these principles. Contradiction.
Thus, gunky objects cannot be numerically identical to regions of spacetime.
Chair: Annica Vieser
Time: September 11th, 17:40 – 18:10
Location: HS E.002
SOPhiA 2026 