Abstract

In lieu of an abstract, here is a brief excerpt of the content:Unibilitas: The Key to Bonaventure’s Understanding of Human NatureThomas M. Osborne Jr.Historians of medieval philosophy have sometimes described St. Bonaventure’s anthropology as dualist or Augustinian. The conventional story runs that the conservative Bonaventure was afraid of contemporary attempts to describe the rational soul as the substantial form of the corporeal body.1 Bonaventure’s relationship to two intellectual trends lends some support to this theory. First, Bonaventure, following Avicebron and Alexander of Hales, believed in universal hylomorphism, holding that all substances, even the angels and human souls separated from the body, are comprised of matter and form.2 If the human soul apart from the body has its own matter, then in what [End Page 227] sense can the soul be the substantial form of corporeal matter? Second, followers of Bonaventure pointed to this difficulty when they held that the body has its own forma corporeitatis.3 It is not surprising that some historians have regarded Bonaventure as a strong dualist. If the soul is a substance apart from the body, then how can it be one substance with the body? Unibilitasis Bonaventure’s answer to this problem.Bonaventure himself is thoroughly aware that he might seem to regard the soul as a complete substance by itself when he describes it as a composition of form with spiritual matter. If the soul is a composition of form and matter, then it is a hoc aliquid and complete in itself. The soul united with the body could not combine into a third substance.4 I will argue that for Bonaventure unibility is this ability of the soul and body to be united as one substance.In the thirteenth century, unibility describes the ability of two different substances or dispositions to become one supposit.5 For example, Bonaventure and Thomas Aquinas use unibility to describe how Christ’s human nature and his divine nature can be one person. Moreover, John of Rupella, Thomas Aquinas, and Bonaventure use unibility to describe how the soul and the body form one substance. Most historians, like E. Gilson and E. Weber, have generally described unibility as the attempt to show how one human person can have both a substance which is spiritual and a different substance which is corporeal.6 Unibility is for them a concept which precedes the Thomistic discovery of the soul as the substantial form of the body. If this interpretation [End Page 228] were correct, then it would be difficult to see how Thomas Aquinas could retain the term. In fact, unibility has a variety of uses which depend upon the context of its appearance and the thought of the one who uses it.The unibility of the soul plays a far greater role in the thought of Bonaventure than it does in the thought of Thomas Aquinas. Bonaventure describes unibility as the specific difference between the angels and humans. Unlike Thomas, Bonaventure thinks that humans, like angels, have both a substantial form and spiritual matter. A human being differs from an angel in that a human’s form can also be the substantial form of a body. Since unibility lies at the heart of Bonaventure’s anthropology, it seems strange that it has not been more thoroughly examined and discussed.The four main sections of this paper roughly correspond to the different contexts in which Bonaventure uses unibility to describe a property of the human soul. The first section shows that unibility is the specific difference that distinguishes humans from angels in the genus of intellectual substances. Second, this difference between humans and angels will be elaborated to show how human souls, unlike angels, are not only movers of bodies, but also perfections of their own particular body. The third section argues that since the soul is the perfection of the body, it is also the one substantial form of the body. The fourth section touches on Bonaventure’s discussion of personhood to show that the human soul when separated from the body is not a person because it is not a fully individual substance. Since an angel is not unitable to a human body, it is unlike a human soul in that it does not need...