From Combinatorialism to Primitivism

Abstract

Modal primitivism is the view that metaphysical modality cannot be reduced to something entirely non-modal. It is often rejected for reasons of ideological simplicity: the fewer primitive notions a theory requires, the better. Reductive theories of modality like Armstrong's combinatorialism are thus thought to hold the ideological high ground. According to combinatorialism, what's possible is reducible to recombinations of objects with fundamental properties and relations. If this reduction succeeds, we have a theory that uses no primitive ideology in its explanation of the modal beyond what we already need to explain the non-modal. Combinatorialism faces two problems: the problem of spatio-temporal relations and the problem of determinates. I argue that in order to get around these problems the combinatorialist must adopt two primitive non-modal notions of her own. I then defend a modal primitivist theory, incompatibility primitivism, which takes as its primitive notion that of incompatibility between properties and relations. Such a theory is systematic and may reduce the combinatorialist's primitive non-modal notions, showing that with respect to number of primitive notions, the modal primitivist comes out ahead. Finally, I argue against reasons to think that there is something especially problematic about primitive modal notions as compared to primitive non-modal notions.