Abstract

A growing number of philosophers have argued against the orthodoxy that the correct principle of composition will be a metaphysically necessary truth. With contingentism about composition a seemingly viable option, it would appear that would‐be necessitarians shoulder the burden of proof. The aim of this paper is to demonstrate that the contingentist, too, has a significant burden. I argue that nonbrutal principles of composition satisfy a principle according to which facts about whether or not a collection composes supervene on noncomposition facts that are spatiotemporally local to the collection. I further argue that the contingentist has reason to reject both brutal composition and the supervenience principle. This reveals a significant internal tension in the contingentist's position. Unless this tension can be resolved, there will be (defeasible) reason to prefer necessitarianism about composition.