Why middle-sized matters: Quantum realism, minds and the Problem of Macro-Objects

Abstract The Problem of Macro-Objects concerns how three-dimensional, middle-sized objects, such as scientists and their measuring devices, can exist in a quantum world. This paper discusses the problem for wave function realism and the primitive ontology approach to quantum mechanics, focussing on Alyssa Ney’s recent two-stage solution, in which macro-objects are functionally reduced to micro-objects and micro-objects are parts of a whole in which they are grounded (the wave function field). It raises metaphysical difficulties with this proposal which a hylomorphic account of wholes may be able to address, noting possible implications for one’s philosophy of mind depending on one’s preferred solution to the Measurement Problem.