The Elements of Avicenna's Physics: Greek Sources and Arabic Innovations by Andreas Lammer
In this timely and outstanding contribution, Andreas Lammer tackles central concepts and problems in Avicenna's Physics of the Healing. The analysis provides a wide-ranging but cohesive study of Avicenna's approach and ideas. The philological and philosophical analysis of the historical context of Avicenna's arguments pays dividends. Avicenna's—often radical—reworking of Aristotle's approach in the Physics critically engages a long tradition of Peripatetic and Neoplatonic philosophy in Greek and Arabic. Lammer's contribution, based on his doctoral dissertation, lays fertile ground for future work. Given the limitations of this review, I focus in the following on the results and fruitful questions raised by chapters 2, 3, and 4. Despite their importance, I set aside chapter 5, which treats Avicenna's defense of Aristotle view of place, and chapter 6, which deals with his attempt to unify Aristotle's reductive view of time with a Platonist view of it as a stable magnitude.
Chapter 1 assesses the translation history of Aristotle's Physics and the status of related commentarial material. Lammer sets the boundaries of what we presently know about Avicenna's sources, which is rather little in terms of direct evidence. Subsequent chapters proceed by piecing together the larger context of ideas that Avicenna would have engaged.
In chapter 2, Lammer assesses Avicenna's method in the exposition of concepts in his Physics, I.1. The central argument of the chapter is a significant one: Avicenna does not set out a method of inquiry into the principles of natural things, which is the dominant understanding of Aristotle's Physics I.1 among ancients and moderns. Rather, Avicenna adopts a mode of instruction. Aristotle begins I.1 with the advice that we start from what is "more knowable and clear to us" and proceed to what is more knowable by nature (which corresponds to the instruction of Posterior Analytics I.2). However, he also states in I.1 that we proceed from the universals (καθόλου) to the particulars. The ancient Greek commentators resolve this tension by reading καθόλου not as natural-kinds universals but as "indiscriminate particulars." Here, Avicenna conspicuously departs. He offers a more "literal" reading of Aristotle, in which 'universal' means what is most "common" in nature and better known to [End Page 168] the intellect. Notably, Avicenna's use of "common things" (al-umūr al-'āmma) corresponds to generic universals, which are better known to the intellect but are not better known "by nature" (a complication of Aristotle's two-part view). Lammer convincingly concludes that Avicenna does not describe a method of scientific research here. However, it remains unclear what mode of instruction means and how it relates to demonstrative proof qua proof. Just as interpreters have attenuated the stronger claim suggested by Barnes that demonstrative method is a purely didactic tool, the above will raise fruitful questions regarding instruction, proof, and the acquisition of first principles in Avicenna. Is the problem one of method versus instruction, or is it one that turns on the status of the acquisition of first principles vis-à-vis the methods of demonstrative science?
In chapter 3, Lammer turns to the subject-matter and principles of physics as discussed in I.2. In contrast to Aristotle, Avicenna does not think we begin with an inquiry into change to arrive at an account of the principles. Rather, he "sets out" or posits form, matter, and privation as the principles of natural things. In fact, Avicenna "decouples" the analysis of body and its essential constituents, as that which undergoes change, from the external or accidental items in virtue of which the body undergoes change (e.g. privation). All this confirms Lammer's point, mentioned above, that Avicenna does not employ a method of discovery of principles. Here, Lammer offers two important revisions that should be highlighted. Regarding the nature of body, Lammer argues against the predominant reading of Avicenna, in which corporeality is viewed as no more than a "predisposition" to become tridimensional or determinately extended—in other words, corporeality is unextended (122–32). By contrast, Lammer argues that corporeality according to Avicenna is indeterminate extension. The textual analysis is convincing but raises philosophical questions regarding the definition and the relation of indeterminate extension to (indeterminate) tridimensionality, as Avicenna considers the latter an accident in the category of quality. Lammer's semantic analysis of farḍ (as "to determine") suggests the determinability of tridimensionality in some unbounded, qualityless extension. This pushes the question back to what, precisely, is the determinability of indeterminate tridimensionality. Moreover, what is unbounded extension if not indeterminate tridimensionality? As Lammer notes, finitude is not essential to the definition of body. Here, Avicenna does not seem to have in mind solely individuating properties or dimensions, which is the focus of Lammer's analysis of determinability, as Avicenna maintains a strict distinction between indeterminate tridimensionality as quantity and unbounded extension as substance. Avicenna's definition seems to mean that the absolute body is (somehow) the ontological ground for such quantitative properties as indeterminate tridimensionality and mathematical bodies, which moves us back towards the traditional reading.
Second, Lammer argues against the "multiplicity of forms" thesis widely attributed to Avicenna. According to Lammer, Avicenna views natural substance as constituted of one species form and (prime) matter; texts that suggest otherwise are "loose locutions" (166–79). Again, though convincing, Lammer's argument raises further questions regarding the nature of intermediary matter and its preparation, especially for higher-order compounds like plants and animals. How is the ordered complexity of forms to be accounted for without any material differentiation? What destroys the elemental forms in such processes? One point that emerges in chapter 3 is Avicenna's commitment to a rather extreme substance occasionalism, where even material division entails a kind of substantial generation. All this raises important problems not just in Avicenna but also for the postclassical tradition.
In chapter 4, Lammer assesses Avicenna's view of nature, which is "as new and unprecedented as a Peripatetic account" of nature could be. Avicenna attacks the predominant conception of nature in antiquity as an independent or soul-like power that permeates bodies. Though he offers a "deflationary" account, Avicenna views nature as an "active principle," in contrast to the passive sense given it by Aristotle in Physics II.1. Avicenna's fourfold classification of natural powers is remarkably elegant and effective in fending off the entitative view of nature. However, Avicenna points to a "universal nature" in Ilāhiyyāt VI.4 as a singular "governing" entity, which does not seem to be addressed by [End Page 169] Lammer. One wonders whether Avicenna reserves the kind of nature misleadingly defined by others in physics for metaphysics. This question, as the questions raised above, far from a detraction, only attests to the rich and productive nature of Lammer's work.