Necessary Existence and the Doctrine of Being in Avicenna’s Metaphysics of the Healing by Daniel D. De Haan

Abstract

Reviewed by: Necessary Existence and the Doctrine of Being in Avicenna’s Metaphysics of the Healing by Daniel D. De Haan Jon McGinnis Daniel D. De Haan. Necessary Existence and the Doctrine of Being in Avicenna’s Metaphysics of the Healing. Leiden: Brill, 2020. Pp. 442. Cloth, $166.00. Avicenna scholars know well that Avicenna (980–1037) aspired to present his metaphysics in the form of an Aristotelian science. The mélange of topics that make up Avicenna’s Metaphysics often appears disjointed and rambling, making it difficult to see how successful he was in this aspiration. Daniel D. De Haan’s book provides an aerial view of Avicenna’s Metaphysics, which argues that Avicenna succeeded. More specifically, De Haan suggests how Avicenna’s conception of the “necessary” links the general subject of metaphysics (namely, being qua being) to its ultimate goal (namely, a scientific study of God). In this respect, De Haan’s work is less of a commentary on Avicenna’s Metaphysics than a metacommentary. Thus, [End Page 158] it is not for a casual reader of the history of philosophy nor of Islamic philosophy nor even of Avicenna’s general thought. It is intended for those who want to take a deep dive into Avicenna’s Metaphysics, and those willing to do so will find De Haan’s text richly rewarding. To contextualize De Haan’s work, let me provide a brief overview of Aristotelian science. According to Aristotle, every science assumes the existence of its proper subject, which is a genus of the things that the science investigates. For instance, physics studies the genus of bodies qua changing. In addition to assuming the existence of its subject, Aristotelian science assumes (1) the definitions of the objects that it studies, (2) various hypotheses or existence claims (e.g. in physics, that change exists), and (3) certain axioms, which are deductive principles. Armed with these “first principles,” one deductively identifies and confirms the various species of objects that fall under the science’s genus as well as the necessary accidents that belong to the genus and its species. Metaphysics poses a challenge to this picture. First, what is its subject? Aristotle and Avicenna both think that it is being/existent qua being/existent, but they also believe that being/existent is not a genus, in which case it cannot function as the subject of a science. Moreover, scientific definitions are given in terms of a genus and difference, but again being/existent is not a genus. Similarly, if being/existent is not a genus, there cannot be species of it to investigate. These are a few issues that loom for Avicenna’s aspirations and that De Haan addresses. Necessary Existence and the Doctrine of Being in Avicenna’s Metaphysics of the Healing consists of four parts: (1) “The Logical Context of the Metaphysics of the Healing,” (2) “Scientific Order of the Metaphysics of the Healing,” (3) “Scientific Principles and the Senses of Being,” and (4) “Basic and Fundamental Principles in the Metaphysics of the Healing.” Part 1 consists of two chapters, in which De Haan presents Avicenna’s own understanding of Aristotelian science. In chapter 1, we see how Avicenna integrates into his account of science the notions of conceptualization (taṡawwur) and assent (taṡdīq) and their relation to the scientific question “What is x?” and “if” there is an x. These notions are central to medieval Arabic epistemology and are also central to the discussion of chapter 2, where we are introduced to how Avicenna envisions scientific definitions and demonstrations. In the two chapters of part 2, De Haan considers how Avicenna’s construal of a demonstrative science applies to metaphysics, specifically exploring the subject and ultimate goal of metaphysics and then verifying metaphysics’ first principles. In general, these chapters are close readings of Avicenna’s Metaphysics, book 1. Chapter 3 takes up the subject of metaphysics, namely, being qua being, where being/existent is viewed not as a genus but a “quasi-genus.” Aristotle’s ten categories serve as being’s “quasi-species,” while its “quasi-proper accidents” are identified with the prior-posterior, act-potency, perfect-imperfect, universal-particular, and cause-effect. The...