This article presents a trope bundle theory of simple substances, the Strong Nuclear Theory [SNT] building on the schematic basis offered by Simons's (1994) Nuclear Theory [NT]. The SNT adopts Ellis's (2001) dispositional essentialist conception of simple substances as powerful particulars: all of their monadic properties are dispositional. Moreover, simple substances necessarily belong to some natural kind with a real essence formed by monadic properties. The SNT develops further the construction of substances the NT proposes to obtain an adequate trope bundle theory of powerful particulars. The SNT allows for co-located powerful particulars. However, every powerful particular is necessarily co-located with its constituent tropes, which determine its causal powers. Every constituent trope of substance i is part of a trope aggregate (the n-bundle or c-bundle) that forms an individual figuring in the basic spatio-temporal relations. The location of these individuals determines the location of individual tropes. Since they are necessarily co-located with substance i when they exist, every trope t of i is necessarily co-located with i when it exits. Every simple substance has nuclear tropes necessary to it. It belongs to certain primary natural kind K because its nuclear tropes belong to certain distinct determinate kinds.

Is it possible to get by with just one ontological category? We evaluate L.A. Paul's attempt to do so: the mereological bundle theory. The upshot is that Paul's attempt to construct a one category ontology may be challenged with some of her own arguments. In the positive part of the paper we outline a two category ontology with property universals and kind universals. We will also examine Paul's arguments against a version of universal bundle theory that takes spatiotemporal co-location instead of compresence or coinstantiation as the feature by which we can identify genuine bundles. We compare this novel theory, bundle theory with kinds, and Paul's mereological bundle theory and apply them to a case study concerning entangled fermions and co-located bosons.

In this paper, we argue for a novel three dimensionalist (3D'ist) solution to the problem of persistence, i.e., cross-temporal identity. We restrict the discussion of persistence to simple substances, which do not have other substances as their parts. The account of simple substances employed in the paper is a trope-nominalist Strong Nuclear Theory (SNT), which develops Peter Simons' trope nominalism. Regarding the distinction between three dimensionalism (3D) and four dimensionalism (4D), we follow Michael Della Rocca's formulation, in which 3D explains persistence in virtue of same entities and 4D in virtue of distinct entities (temporal parts). SNT is a 3D'ist position because it accounts for the persistence of simple substances in virtue of diachronically identical 'nuclear' tropes. The nuclear tropes of a simple substance are necessary for it and mutually rigidly dependent but distinct. SNT explains qualitative change by tropes that are contingent to a simple substance. We show that it avoids the standard problems of 3D: temporal relativization of ontic predication, Bradley's regress, and coincidence, fission and fusion cases. The temporal relativization is avoided because of the analysis of temporary parts that SNT gives in terms of temporal sub-location, which is atemporal part-whole relation.

This paper is the first trope-theoretical reply to E.J. Lowe's serious dilemma against trope nominalism in print. The first horn of this dilemma is that if tropes are identity dependent on substances, a vicious circularity threatens trope theories because they must admit that substances are identity dependent on their constituent tropes.According to the second horn, if the trope theorist claims that tropes are identity independent, she faces two insurmountable difficulties. (1) It is hard to understand the ontological dependence of tropes on substances. (2) The identity-conditions of tropes cannot be determinate, which threatens the determination of the identityconditions of substances. Our reply to the first horn of Lowe's dilemma is to deny the identity dependence of tropes. Yet we can avoid the second horn because our theory