# New York Philosophical Logic Group

Achille Varzi, Columbia University

Gunky Models for Atomistic Mereology

Abstract: It is customary practice to define ‘x is a composed of the ys’ as ‘x is a sum of the ys and the ys are pairwise disjoint (i.e., no two of them have any parts in common)’. This predicate has played a central role in the debate on the special composition question and on related metaphysical issues concerning the mereological structure of objects. In this talk I shall argue that its customary characterization is nonetheless inadequate. In particular, there are perfectly classical (even extensional) mereological models in which everything qualifies as composed of atoms although some elements in the domain are gunky, i.e., can be divided indefinitely into smaller and smaller proper parts. That is bad news for the mereological atomist. Even worse, I think, is the moral one should draw in relation to the broader picture, beginning with our understanding of mereological composition tout court. I will conclude with some remarks concerning the sort of mereology that is needed to block the problem.