This first volume dedicated to Aristotle’s natural philosophy in the series of Cambridge Critical Guides deals with the Physics and testifies to its richness: it offers food for thought not only for those who are primarily interested in a very different picture of physical reality, but also for those who like to rethink nature and natural science in the light of metaphysical issues. As Mariska Leunissen puts it in her “Introduction”, the Physics not only “lays out Aristotle’s conceptual apparatus and methodological framework for all of his natural philosophy” (1), but “forms the conceptual entry-way into much of the Aristotelian Corpus” (2), including metaphysics and, to a lesser degree, political science and ethics. The contributions to the volume set out to justify this claim; they are not meant to introduce us to the Physics and its textual history or to offer a general overview of recent scholarship.1 Instead, the editor’s introduction summarizes three tasks of the book as (I) “reassessing the key concepts of Aristotle’s natural philosophy”; (II) “reconstructing Aristotle’s methods for the study of nature”; and (III) “determining the boundaries of Aristotle’s natural philosophy” (2-4). These tasks do not organize the volume into distinct parts, but serve as the axes of research that all the contributors keep in mind, although naturally, given the range of topics discussed, with different accents.
While the structure of the resulting “Critical Guide” does not therefore map onto the internal divisions of the Physics, its progress still reflects the latter’s broad architectonics. It is thus logical that the issue of boundaries appears in its two distinct acceptations in the opening and the closing chapters: the first chapter looks at how Aristotle delimits the method of natural science; the last one revisits the borderline between the physical and the metaphysical. James G. Lennox starts with methodology, and his chapter discusses both the broad methodological conformity of the Physics to the Posterior Analytics and the specificity of Aristotle’s physical inquiry within this framework. Seen in this light, the study of natural bodies together with the conditions of their various changes (the study carried out most clearly in Physics II-IV with its focus on nature, causation, change, and motion plus place and time), appears to play the role of “the conceptual foundations of natural science” (30). Other inquiries into natural bodies deploy their own methodological norms, but they cannot avoid using concepts discussed most thoroughly in the Physics.
As Lennox reminds us, that there is change, and thus that nature is its principle is, for Aristotle, plainly obvious. But what change and thus nature is, remains to be determined. Sean Kelsey offers a succinct discussion of how Aristotle takes up this task in Physics II. Kelsey brings together two strains of this book: the definition of nature as a principle of motion and rest, and the view that nature is form rather than anything else. Hence the conclusion, only implicit in Aristotle, is that form is the principle of motion. This break with both the Presocratic and the Platonic views of how motion can be initiated necessitates a new explanation of how form can move things. Kelsey’s suggestion is that Aristotle crucially relies on “the fact, mentioned in II 7, that ends are kinetic principles too” (41). This is how the form, by being an end, conditions natural beings to precisely that activity that enables the form to be perpetuated in its enmattered state. By the same token, the charge of Platonism is preempted.
Another discussion of nature as the principle of change comes from Stasinos Stavrianeas whose focus is on the definition of nature. On his reading, this amply conceived (rather than scientifically exact) definition enables the inquiry into nature to accommodate phenomena as different as the motion of the inanimate elements and the generative motions of animate bodies. Implying the inherence of nature as principle of motion (including generation) in the moving thing, this definition is also helpful in distinguishing between natural bodies and artifacts, including the seemingly miraculous automata. This inherence is then what opposes nature as cause to accidental cause whose character is discussed by James Allen. The virtue of Allen’s contribution lies in making chance intelligible from within the teleological framework that it would seem to oppose. On a closer look, such an opposition dissolves and we can understand various chance events as additional outcomes of generally successful teleological processes. Bluntly put, chance has thus no chance to rule the natural world.
This conclusion is confirmed by Margaret Scharle’s analysis of the famous rainfall-example in Physics II.8. Winter rain is integrated into Aristotle’s natural teleology since its regularity is not coincidental, but makes up part of the cycles whereby nature imitates the divine. Scharle reads the passage in question in the light of other texts including Metaphysics XII 10, and concludes that the example of winter rain points to a regularity which cannot be brought forth by art. Still, as the next chapter shows, Aristotle’s equally renowned craft analogy finds its legitimate place in the Physics. Charlotte Witt argues that this analogy has its own role to play in Aristotle’s argumentation in favor of natural teleology; in fact, it informs his most extensive argument of this kind, which relies on the presence of intrinsic ends in both art and nature. This analogical goal-directedness is conceptually secured by Aristotle’s claim that art does not require deliberation (II 8, 199b27-30), a claim that confirms his seriousness about the analogy.
Robert Bolton reexamines the core of Aristotle’s teleology as presented in Physics II, without neglecting its connections to other parts of the corpus. Rejecting the alleged proximity of the Aristotelian and the Platonic teleologies, defended by some recent readers, Bolton argues for Aristotle’s own conception as hanging on the irreducibility of final causation to efficient (or any other) causation: in nature, evaluative goals determine the goal-directed fitness and, as such, are clearly more than “regular consequences”.2
Devin Henry deals with substantial generation in Physics I 5-7 and concludes that Aristotle’s introduction of this generation as a genuine kind of change need not imply that generation of a new substance involves a persisting subject. Diana Quarantotto offers a broader view on how Aristotle’s physics articulates the relation between being and change. She argues for a shift in perspective that occurs between Books I-III and Book VIII: if the former maintain the clean-cut distinction between being and change while “giving priority to being over change”, the latter concludes that “the substantial being ( ousia) of natural entities is accomplished through a particular kind of change (eternal change), and hence that being in its primary sense is itself dynamic” (162). To support this ambitious interpretation, Quarantotto rereads On Generation and Corruption II.10, where the circular transformation of the elements appears as the glue of the universe, and precedes all other sublunary changes. The ordering of the all is then due to the “top-down causal chain of the world stemming directly from the P[rime] M[over]” (183) through the celestial realm to the circular generation of elements. Encompassing all levels of the universe, this view “from above” suggests a gradualist perspective on being and, at the same time, a deeper complicity than it is usually assumed between having an ousia and striving at eternal being.
The aim of David Charles’ contribution is to demonstrate that Aristotelian changes (κινήσεις) are processes and not events as some recent interpreters have suggested. Even if κίνησις can change its properties at various times, it is no less a continuant than substances or actions are. While analyzing actualities in Physics III and Metaphysics IX, Aristotle sees κινήσεις and substances as “having analogous but irreducibly distinct roles” (2004), and his ontology is designed so as to bring out their similarities as well as their differences. Charles’ analysis has some subtle affinities with Jacob Rosen’s approach to the arguments in Physics VIII 8 for the thesis that an upward and a downward motion of the same object do not compose a single motion, a thesis which supports the claim that the only eternal motion is circular, not rectilinear. Reading these arguments against the background of Books V-VI on changes and continua, Rosen highlights the difficulties that stand in the way of seeing Books V, VI and VIII as espousing a unique theory of continua and eternal motion. More specifically, Book VIII endorses what Rosen calls the Potentiality Doctrine (“a continuous entity has no actually existing proper parts and no actually existing middle-points”, 207), which seems difficult to reconcile with the non-homogeneity of motion in Books V-VI. Also, Physics VIII 8 assumes a beginning of change, but Physics VI 5 proved that there was no such thing. Rosen concludes that Books V-VI do indeed preempt the later negative arguments against the possibility of eternal rectilinear motion, but Aristotle can still secure the priority of circular over rectilinear motion by other arguments available in the corpus.
Mariska Leunissen’s chapter stands out by going beyond the realm of physics proper not in the direction of metaphysics, but of ethics and politics. Dealing with how Physics VII 3 presents the physical changes which are involved in the acquisition of virtues, she analyzes Aristotle’s claim that “character virtue comes to be when the perceptive part of the soul is altered through perceptibles” (243). Her conclusion is best quoted in full: “character virtue is only possible when all of the constitutive capacities of the perceptive soul are in their best condition and are proportionally organized, and the resulting virtuous disposition will constitute one, unified, but distinct psychological state” (244). What this means is that character virtue does not itself follow from a generation or an alteration but, being relational, it is conditioned by a fine physiological tuning of our perceptive soul. Leunissen’s analysis can certainly bring new nuance to the debates about Aristotle’s moral naturalism and its background.
Ursula Coope turns to the much-discussed account of self-motion in Physics VIII 5. Starting with Aristotle’s notion of self-motion as other-motion (all self-movers divide into a moving part, which is at rest, and a moved part), Coope shows how Aristotle argues, more generally, for the existence of an entirely unmoved mover which helps him to account not only for the case of the self-moving animals, but also for the first eternal movement which must be caused by something entirely at rest.
The unmoved mover is also in the foreground of the volume’s last chapter. Andrea Falcone submits that Physics VIII treats the first unmoved mover within the boundaries of natural science, where Aristotle first demonstrates that there is eternal continuous motion, and then asks what exactly such motion is. At this second stage of his explanation, the unmoved mover enters the picture as this motion’s (apparently efficient) cause. Here the first unmoved mover secures the coherence of the physical treatment of circular eternal motion. It thus need not receive any positive description. The latter is only offered, on a different basis, in Metaphysics XII.
In sum, this is an excellent collection where each contribution stands on its own, yet non-trivial correspondences are plentiful and invite further inquiries. The volume is well-produced and the only cause for regret is the absence of an Index locorum which, however, characterizes the whole series.
2. The Bibliography at the end of the volume does not distinguish between two different Nagels that Bolton refers to: his note 19 refers indeed to Ernest Nagel and his etiological account of natural teleology; note 23, however, refers to Thomas Nagel and his insistence on the evaluative dimension of teleology.