- Aquinas on the Metaphysics of the Hypostatic Union by Michael Gorman
This volume explores Thomas Aquinas's metaphysical account of the Incarnation, in which Jesus Christ is understood to be one person with two distinct natures. Gorman helpfully begins with an overview of the dogmatic determinations established by the early Church's ecumenical councils; these framed the parameters (and limits) within which theologians could develop their metaphysical accounts of the hypostatic union and remain orthodox. Coupled with this dogmatic framework is the more proximate tradition of Christology articulated in the Sentences of Peter Lombard, wherein three Christological "tendencies" are advanced: assumptus homo, subsistence, and habitus. Without addressing the particulars of each tendency, Gorman notes that Thomas, like most of his contemporaries, prefers the second (subsistence theory) over the others, and it is the task of Thomas's metaphysics of the Incarnation to explain what is involved in that approach. The success of Thomas's project is not always clear insofar as he leaves undeveloped or opaque what some would desire to be clearer or more definitive. Gorman's project, then, attempts to be both historically accurate and speculative and, in both cases, as intellectually honest as possible.
The first chapter addresses Thomas's understanding of "person" and "nature." The usual catalog of associated metaphysical terms (e.g., "hypostasis," "suppositum," "res naturae," "substance") emerging from the classical Boethian definition of "person" comes to the fore. Here, Gorman makes a rather peculiar claim regarding Aristotle's notion of "second substance": "'second substance' means approximately the same thing as 'nature' (this is the sense of substance that is at work in a phrase like 'consubstantial with the Father')" (15). It is far from evident, however, that the όμοουσιος is the same as Aristotelian "second substance," for the reason that the latter relates to first substance as a species or a genus (i.e., a universal) does to a particular subject (i.e., ύποκείμενον). But what sense does it make to say that the "nature" of God is a universal or a species? Would that be to imply that the Father, Son, and Holy Spirit stand as individuals (first substances?) within the same species, or even species within the same genus of deity? The first option would result in polytheism, the second in absurdity.
Be that as it may, the remainder of the chapter elucidates Thomas's account of substance, which has four determining features—the most important of which is "subsistence," followed by "individuality," "substanding," and "unity." Accordingly, if a person is a special kind of substance, persons too will enjoy these same four characteristic marks of substance. Given that a "person" is a substance of a peculiar kind of nature, Gorman treats what "nature" means for Thomas. Though said in many ways, the relevant form of "nature" in discussions of personhood is "substantial nature," which functions [End Page 309] as a supposit-grounder: that in virtue of which something subsists as a suppositum. Moreover, a substantial nature makes something subsist by making it to be a subsisting thing of a certain kind.
Chapter 2 relates Thomas's metaphysical understanding of (personal) substances to the dynamics involved in the Incarnation itself. As a nature is that whereby something subsists as a certain kind of thing, to say that Christ has two natures is to say that Christ subsists as both divine and human. Moreover, as natures are principles of operations, insofar as Christ acts through his human nature (e.g., healing, suffering), the divine person himself undertakes these actions. Gorman helpfully draws attention to a special sense in which it is said that Christ assumes a "human nature." "Human nature" as such only pertains to that which is proper to being a human, namely, a "rational animal." Yet, within a human being there is more than just "rational animal," since human beings enjoy a variety of accidental features and particular determinations that emerge from their human nature. This latter, broader category is what Gorman calls "human reality" (45). He suggests...