Composition Identity and Emergence

Composition as Identity (CAI) is the thesis that a whole is, strictly and literally, identical to its parts, considered collectively. McDaniel [2008] argues against CAI in that it prohibits emergent properties. Recently Sider [2014] exploited the resources of plural logic and extensional mereology to undermine McDaniel’s argument. He shows that CAI identifies exten- sionally equivalent pluralities  he calls it the Collapse Principle (CP)  and then shows how this identification rescues CAI from the emergentist argument. In this paper I first give a new generalized version of both the arguments. It is more general in that it does not presuppose an atomistic mereology. I then go on to argue that the consequences of CP are rather radical. It entails mereological nihilism, the view that there are only mere- ological atoms. I finally show that, given a mild assumption about property instantiation, namely that there are no un-instantiated properties, this ar- gument entails that CAI and emergent properties are incompatible after all.