Hylomorphism and the Causal Closure of the Physical

Abstract Howard Robinson has criticized the contemporary revival of hylomorphism for, on the one hand, accepting the causal closure of the physical, while, on the other, ascribing a real and irreducible causal role to forms or structures. If the world is causally closed under physics, it makes no sense to postulate a structure that actively affects the distribution and motion of matter. After carefully formulating what I call Robinson’s causal closure argument against hylomorphism , I demonstrate that the argument fails because it presupposes an overly strict conception of causal closure of the microphysical, according to which every physical effect is completely determined by, and has a complete explanation in terms of, bottom-level microphysical entities and their interactions governed by fundamental physical laws. Based on two case studies – one from physics (the Fractional Quantum Hall Effect), the other from microbiology (information control in microorganisms) – I argue that the argument fails, yet a more modest (and scientifically defensible) version of closure remains intact. This version of closure secures that no non-physical forces supplement the inventory of fundamental physics while allowing higher-level constraints to be causally efficacious by constraining which among multiple microphysically compatible possibilities is actualized. This means that a reformulated version of closure, capable of dealing with those cases, is also perfectly compatible with the hylomorphist (or generally anti-reductionist) claim that higher-level structures are causally efficacious and an irreducible part of physical reality.