I've just finished revisions to my "Illusions of gunk" paper. This defends microphysical mereological nihilists (folks who think that the only particulars that exist are microphysical simples) against Ted Sider's argument that they run into gunky trouble.
The paper is up here, and the abstract follows:
The possibility of gunk has been used to argue against mereological nihilism. This paper explores two responses on the part of the microphysical mereological nihilist: (1) the contingency defence, which maintains that nihilism is true of the actual world; but that at other worlds, composition occurs; (2) the impossibility defence, which maintains that nihilism is necessary true, and so gunk worlds are impossible. The former is argued be ultimately unstable; the latter faces the explanatorily burden of explaining the illusion that gunk is possible. It is argued that we can discharge this burden by focussing on the contingency of the microphysicalist aspect of microphysical mereological nihilism. The upshot is that gunk-based arguments against microphysical mereological nihilism can be resisted.
One thing that I argue for in the paper is that microphysical mereological nihilists are committed to a more far reaching error-theory than you might initially have thought: not only are there no cats and dogs (or compound objects), but there could not have been cats and dogs (or compound objects). I mention in a footnote that this seems to me a real problem for the "counterfactual" fictionalist strategy that Cian Dorr favours to explicate nihilism. Basically, if "cat" isn't even assigned an intension (as I argue), then "were things to compose but the arrangement of subatomic particles to be exactly as it actually is, then there'd be cats" will be false.
There are problems for alternatives to Dorr's account too (e.g. I never understood what sense Van Inwagen is supposed to make out of English plural sentences such as "some authors admire only one another"). One future project of mine is to develop a way of doing vanilla possible world semantics in a nihilist world, by tweaking the story about how possible worlds, and possibilia, are constructed...