Physicalism is one of the philosophical approaches that explain the world as a physical property. Is arguable that the answer to this question should come primarily from physics, i.e. physics conceived as a special science? Some precedent for this can be found in Aristotle’s physicalism and more specifically in the elementalism that is its physical basis. Of course, the intellectual activity that is the ultimate form of which all other forms are a lower manifestation is conceived by him as eternal, and hence as coeval with the basic kinds of stuff. Therefore the latter never would exist on their own without the existence of the former to which to conform. Nevertheless in themselves, they are, as we have noted, spatially and quantitatively indeterminate. Their only intrinsic distinguishing features are purely qualitative. Philosophers suppose that matter as a composite of subatomic particles is, while unobserved, in that sort of probabilistic state that is mathematically represented by a wave function, and this state is further conceived as spatially indeterminate — as a distribution of alternative locations. Indeed, even a system that includes such particles and an observer who observes them is, in estimation, similarly indeterminate while unobserved by further observers, i.e. about these further observers (Heil 43). However, in any system taken as a whole, the wavelike quantum superposition of its subatomic particles, which the wave function represents, is collapsed or reduced to a determinate reality through interaction with the mental activities of that system’s observer. In this, the status of the mind’s own thing does not appear as problematic. For him, it would seem, an accomplishment of contemporary physics has been to update Descartes just by offering a more radical conception of what the effect of the mind’s intervention must be. On this view, in addition to affecting the motion and rest of the physical world, the mind imbues that realm with the phenomenological definiteness that it observes therein (Heil 41). The physicalism of this sort is, however, transposable into one that is physical. The order of explanation can just be reversed. Thanks to the Modal Identity Thesis, instead of attributing the introduction of determinate physical characteristics to the intervention of the mind, we can identify the mind or its activities with the introduction of a certain degree of determinacy (Heil 22). The claim must be that in certain parts of the cosmos the quantum-mechanically determined particles aggregate over time into physical ensembles of a distinctive kind. These ensembles constitute a form of emergent composition whereby the wave functions of their components collapse progressively and conjointly into determinacy. the probability distributions are channeled into divergent branches of equally possible determinate alternatives any one of which may serve as a node for the divergent branching of further channels. This, no doubt still makes a mystery of what the cosmos is like when none of the required types of ensemble happen to exist. But that is a mystery to which contemporary physicists are for the most part resigned (Heil 173). Physicalism has set out to explain how a reality that instantiates determinate characteristics in an indeterminate way