Non-reductive Physicalism and Degrees of Freedom∗

∗Thanks to audiences at Tufts University, the University of Kentucky, and the University of Toronto for helpful comments and questions. Special thanks to Benj Hellie and Jonathan McCoy for detailed feedback on previous versions, and to Robert Axtell, whose suggestion that reductions in degrees of freedom play a role in the physically unproblematic emergence of complex systems (made during the 2002 Case Studies of Emergence seminar series at the University of Michigan) inspired the present approach. †Department of Philosophy, University of Michigan, Ann Arbor; [email protected] The expression “broadly scientific entities” here covers any of the entities that are among the subject matters of any of the sciences, from fundamental physics up through linguistics, psychology, and beyond. Although structured or unstructured collections of entities may also be entities, I will sometimes use the term ‘system’ to refer to such collections. Physicalism is, I’ll assume, neutral on whether entities that are not broadly scientific—perhaps mathematical or metaphysical entities, such as numbers or universals—are nothing over and above physical entities. There are two supposed routes to this conclusion. One (of the sort found in Nagel 1961) takes establishing the physical acceptability of an entity to concurrently establish its ontological reducibility. The second (of the sort found in Kim 1989 and 1993a) takes ontological irreducibility to invoke causal overdetermination, unless robust emergence is embraced.