Aquinas has much to say about individuation over the course of his career. Although certain aspects of his views appear to undergo development, there is one aspect that remains constant throughout—namely, his commitment to assigning both prime matter and quantity an essential role in the individuation of substances. This paper examines the vexed issue of how either prime matter or quantity, as Aquinas understands them, could have any role to play in this context. In the course of doing so, the (...) author attempts to put to rest a number of longstanding worries about the coherence of Aquinas’s views about individuation, as well as to draw out some of his broader commitments in metaphysics and natural philosophy that have yet to be fully appreciated. (shrink)

Plenitude, roughly, the thesis that for any non-empty region of spacetime there is a material object that is exactly located at that region, is often thought to be part and parcel of the standard Lewisian package in the metaphysics of persistence. While the wedding of plentitude and Lewisian four-dimensionalism is a natural one indeed, there are a hand-full of dissenters who argue against the notion that Lewisian four-dimensionalism has exclusive rights to plentitude. These ‘promiscuous’ three-dimensionalists argue that a temporalized version (...) of plenitude is entirely compatible with a three-dimensional ontology of enduring entities. While few would deny the coherence of such a position, and much work has been done by its proponents to appease critics, there has been surprisingly little by way of exploring the various forms such an ontology might take as well as the potential advantages of one plenitudinous three-dimensional ontology over another. Here I develop a novel form of plenitudinous three-dimensionalism, what John Hawthorne (Metaphysical essays, 2006a, b) has called “Neo-Aristotelian Plenitude,” and argue that if one is inclined to endorse an abundant three-dimensional ontology, one is wise to opt for a plenitude of accidental unities. (shrink)

Gordon P. Barnes has recently argued that presence by power is inadequate as an explanation of the way elements are present in complex bodies, and that it would be better to explain the elements’ presence by claiming that simpler substances—carbon atoms, for example—are actually and substantially present in living things. In order to address his arguments, this paper begins by briefly presenting St. Thomas’s understanding of presence by power, and then argues that Barnes’s proposal—that there is a multiplicity of substantial (...) forms in one matter—is unsatisfactory. First, the paper explains why the scientific facts do not require a plurality of substantial forms. Second, it shows how Barnes’s theory does not adequately explain living things. Third, it argues against Barnes’s claim that St. Thomas’s explanation is insufficient because it denies "the universal causality of nature.". (shrink)

For later medieval philosophers, writing under the influence of Aristotle’s natural philosophy and metaphysics, the human soul plays two quite different roles, serving as both a substantial form and a mind. To ask the natural question of why we need a soul at all – why we might not instead simply be a body, a material thing – therefore requires considering two very different sets of issues. The first set of issues is metaphysical, and revolves around the central question of (...) why a human being needs a substantial form. The second set of issues is psychological, and turns on the question of why we should suppose that our mind is aptly characterized as a soul. This chapter takes up these two questions in turn, and then turns to whether we should suppose that one and the same thing – a soul – is both substantial form and mind. This dual-function thesis is the most distinctive feature of later medieval psychology, and is one reason that work from this era remains well-worth reading today. Whereas modern thought furnishes many sophisticated discussions of the immateriality of mind, and the metaphysics of body, philosophers since Descartes have rarely considered that it might be one thing, the soul, that accounts for both thought and substantial unity. (shrink)

Chapter one serves as an introduction to the whole dissertation. In it I explain why I think philosophers should pursue a systematic, pluralist account of contemporary property roles and consider Thomistic explanations of such roles. I also summarize in more detail the chapters that make up this dissertation. In chapter two I explain the metaphysical and semantic roles that properties are thought to play and briefly introduce the main contemporary accounts of properties in terms of which property roles they address (...) and which they have trouble explaining. In chapter three I consider one contemporary view of properties, namely robust Platonism regarding properties, which is explanatorily powerful but which has some objectionable features. I address one such feature that is of interest to theists. I show the failure of a recent attempt to reconcile robust Platonism regarding God’s attributes with the classical theist views that God is ultimate in the explanation of all reality and that God does not depend on anything distinct from Himself for His existing or His intrinsic attributes. I argue further that there seems to be no other possible way to reconcile them. In chapter four, which is a brief interlude, I clarify some important differences between the account of the divine ideas on one type of theistic Platonism that I critique in chapter three and the accounts given by Augustine and by Aquinas. In chapter five I disambiguate some of the various uses of property terms in contemporary Aquinas scholarship and resolve one substantive disagreement regarding what for Aquinas should be regarded as ‘properties’. Then I critique and modify some features of Jeffrey Brower’s reconstruction of Aquinas’s account of the same-species relation and use the modifications in my own account, which yields a distinctive explanation of the metaphysical property role of accounting for the substantive similarities between things. In chapter six I lay some groundwork for a Thomistic account of the metaphysical property roles of accounting for the characteristics and metaphysical constitution of individual things. I do so by critiquing and modifying Brower’s account of Aquinas’s hylomorphism as a unique type of substratum theory. (shrink)

The first unquestionably big idea in the history of philosophy was the idea of form. The idea of course belonged to Plato, and was then domesticated at the hands of Aristotle, who paired form with matter as the two chief principles of his metaphysics and natural philosophy. In the medieval period, it was Aristotle’s conception of form and matter that generally dominated. This was true for both the Islamic and the Christian tradition, once the entire Aristotelian corpus became available. For (...) this reason, although there is much to say about the fate of Platonic Forms in medieval thought, the present chapter will focus on the Aristotelian tradition.1 Aristotelian commentators have been puzzled by form and matter for as long as there have been Aristotelian commentators. Indeed, it would not be too much to say that these are topics about which Aristotelians have never formed a very clear conception, and that their failure to do so was the principal reason why Aristotelianism ceased to be a flourishing research program from the seventeenth century onward. For those who aspire to a modern revival of Aristotelianism, the concepts of form and matter can easily take on the aspect of a kind of Holy Grail, such that if only we could get these ideas clearly in focus, we could see our way forward on any number of philosophical fronts, such as the union of mind and body, the coherence and endurance of substances, the nature of causality, and so on. The historical record, however, suggests that this hope is a snare and delusion, insofar as there has never been any such thing as the theory of form and matter. Although medieval philosophers of all kinds used this terminology incessantly, it had no more of a fixed meaning than does the ubiquitous contemporary philosophical talk of “properties.” Hence, the most a general survey of the topic can do is consider some of the more important areas of agreement and disagreement. (shrink)

Aquinas distinguishes four types of part included in a hypostasis (’suppositum’): (1) kind-nature; (2) individuating feature(s); (3) accidents; (4) concrete parts. (1) - (3) in some sense contribute ’esse’ to the ’suppositum’. Usually Aquinas holds that Christ’s human nature does not contribute ’esse’ to its divine ’suppositum’, since it is analogous to a concrete part of its ’suppositum’. This effectively commits Aquinas to the Monophysite heresy. In ’De Unione’ Aquinas argues instead that Christ’s human nature contributes ’secondary ’esse‘ to its (...) divine ’suppositum’. This account is coherent and orthodox, but sacrifices explanatory power. (shrink)