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Abstract
In chapter one, I distinguish between material objects and material substances. I then argue that material substances – ontologically independent beings – are substantially simple (i.e., material substances lack substantial parts). The argument for this turns on showing that only material substances can bear basic, non-structural properties. I then argue that human beings are material substances, and hence are substantially simple.
In chapter two, I lay out a basic picture of the ontological structure of material substances: namely, I argue that material substances are what some (see, Brower 2014) call hylomorphic compounds of matter and form. Call this position the Thomistic Substratum Theory of material substances. I argue that the Thomistic substratum theory generates a hierarchy of compounds – substances and accidental unities – that prove to be explanatorily advantageous.
In chapter three, I defend the thesis that there are macroscopic material substances that lack substantial parts against a handful of objections to the contrary. I then discuss how the Thomistic Substratum Theorist could account for the existence of (non-substantial) parts of material substances.
In chapter four, I return to discuss the nature of material objects in general, paying close attention to non-substantial material objects. I argue that non-substantial material objects are accidental unities. In order to adequately explain this position, I turn to a more detailed examination of accidental unities and distinguish between substantially simple and complex unities. I argue that most of the non-substantial material objects we encounter in the world around us (e.g., artifacts) are substantially complex accidental unities. I then explain what the parts of such material objects are. Finally, I turn to discuss how this account can avoid several of the classical (and recalcitrant) ontological problems – e.g., the problem of the many, the problem of causal overdetermination, etc. – by appealing to the notion of a metaphysical grounding relation, which also might alleviate some of the parsimonious concerns regarding the permissiveness of Thomistic Substratum Theory.
