Extended Simples, Unextended Complexes

Abstract

Both extended simples and unextended complexes have been extensively discussed and widely used in metaphysics and philosophy of physics. However, the characterizations of such notions are not entirely satisfactory inasmuch as they rely on a mereological notion of extension that is too simplistic. According to such a mereological notion, being extended boils down to having a mereologically complex exact location. In this paper, I make a detailed plea to supplement this notion of extension with a different one that is phrased in terms of measure theory. This proposal has significant philosophical payoffs. I provide new characterizations of both extended simples and unextended complexes, that help re-evaluating the question of whether such entities are metaphysically possible. Finally, I advance several suggestions as to how different notions of extension relate, first, to one another and, second, to mereological structure.

Mereological Models of Spacetime Emergence

“…Note however that some non‐mereological notions of extension have been developed. Pickup (2016) for instance, claims that something may also be unextended by having no location in space whatsoever; and Calosi (2023) provides an alternative measure theoretic notion of extension. Perhaps one of these non‐mereological notions of extension is better suited in the context of applying a non‐spatiotemporal mereology.…”