BMCR 2000.07.10

Aristotle’s Physics. Book VIII

, Aristotle's Physics. Book VIII. Oxford: Clarendon Press, 1999. xvii + 209. $24.95 (pb).

This volume is by my reckoning the sixteenth in the Clarendon Aristotle Series. The series began in 1962 with the publication of Richard Robinson’s translation of and commentary on Books III and IV of Aristotle’s Politics. Over the ensuing decades, a good deal of important and highly influential philosophical scholarship on Aristotle in English has appeared in these commentaries. Jonathan Barnes’ Posterior Analytics and Julia Annas’ Metaphysics M and N are two distinguished examples. The present volume meets the generally high standard set by its predecessors.

Aristotle begins Book VIII of his Physics with the claim that motion in the universe is everlasting, that is, that it had no beginning and will have no cessation. He ends Book VIII with the claim that everlasting motion can only be explained by an immaterial first unmoved mover. This unmoved mover has always been identified with Aristotle’s divine first principle in his Metaphysics, the god who moves the universe by being an object of desire. The bulk of the Book is largely an exceedingly complex set of arguments for the above two claims. The crucial premise that allows him to move from the first claim to the second is that everything that is in motion is caused to be in motion by something. The principle must be demonstrated inductively for the three main categories of motion: lifeless things in general, the elements which have their own special type of motion, namely, natural motion, and the self-motion of animals. The last two are most important for the purposes of this Book, because they are likely to be the categories wherein is found the motion that guarantees everlasting motion in the universe.

Aristotle argues for all three cases that the ultimate cause of any motion is motionless or immovable. Generally, if a putative B were taken to be the cause of a motion A, and if B were itself in motion, then the motion A is in fact identical with the motion AB, which itself needs to be explained. Even in the case of the so-called ‘self-motion’ of animals, the cause of this motion cannot itself be in motion, but must be a part of the animal that is in fact motionless or immovable. If the entire animal is in motion, the cause of this motion must be a part that is not itself directly or essentially in motion, but moves only accidentally when the whole moves. It follows, then, that if there needs to be a single everlasting motion to account for the necessity of there always being some motion in the universe, this motion too will need to be caused by something motionless, namely, an unmoved mover. This is the core of the Book’s argument. Although the principle Aristotle defends is that everything that is moved is moved by something, his argument leads him to conclude that everything that is moved is moved by something else, namely, something that is unmoved or immovable. Hence, the Scholastic version of Aristotle’s principle: omne quod movetur ab alio movetur.

Clearly, this Book and this argument are pivotal in Aristotle’s entire philosophy. For here we have apparently the precise connecting link between physics, the science of nature, and theology. And since, as Aristotle tells us in Metaphysics VI, first philosophy or the science of being qua being and theology are the same thing, and without the divine physics would be first philosophy, the fate of metaphysics itself hinges on the cogency of his argument. Unfortunately, the matter is clouded by the fact that it is not certain that the unmoved mover reached in Book VIII is the same as the unmoved mover described in Metaphysics Book XII. It is not even clear that the way the unmoved mover moves in Book VIII is as a final cause, which is the way the unmoved mover moves in Metaphysics. This is so because it is not clear that an immovable part of a first mover is identical with an immovable substance that exists separately. The obscurity remains even apart from considerations regarding the soundness of Aristotle’s argument. It is disappointing to say the least that when Aristotle turns to the proof for the existence of the unmoved mover in Metaphysics XII, he merely alludes to Book VIII of Physics without further explication.

These problems were recognized at least as early as the commentary on Physics by Simplicius, who, after a long and detailed discussion of the pros and cons, concludes that the unmoved mover is both a final and an efficient cause. But Simplicius does not attempt to explain how an efficient cause can be absolutely unmoved according to Aristotle’s own principles of motion and causality.

Graham’s translation and commentary strive for the utmost clarity in the presentation of the argument and the alternative interpretations. In this he seems to me to have been largely successful. Especially valuable is an eight page outline of the argument supplied as an appendix. This outline is generally accurate, although the claim in Graham’s schema (1) (B) (6), based on 251b28-252a5, seems to be a misleadingly brief summary of what is said in that paragraph regarding the crucial point that motion cannot ever cease.

The translation is in general highly accurate and if supplemented by Graham’s outline of the argument probably makes this portion of Aristotle’s work as clear as it is going to be, especially to the Greekless reader. One quibble I have is that Graham regularly translates ἀκίνητον as ‘unmoved’ whereas this term in Physics is used ambiguously for ‘unmoved’ and ‘immovable’ (see 221b12-14 and 226b10-15). Graham does not flag this ambiguity in the commentary. But the ultimate mover that is ἀκίνητον is in fact immovable and not merely unmoved, whereas the mover in a self-mover is unmoved but not immovable. One might at least wonder whether Aristotle takes advantage of the ambiguity in his move from his explanation of self-motion to his claim for an immovable first mover. I also do not think it is helpful to translate the traditional bipolarity τὰ κατὰ συμβεβηκότατὰ καθ’ αὑτά as ‘intrinsically’—’incidentally’ rather than the usual ‘accidental’—’essential’, though Graham does not hesitate to use the terms ‘accident’ and ‘essence’ in his commentary. It is also perhaps not ideal to translate γίγνεσθαι as ‘comes to be’ rather than the less ambiguous ‘to be generated’.

The commentary itself, constituting almost three-quarters of the entire book, is admirably clear and judicious. It is, however, less than ideal in at least two respects. First, since it is not a line-by-line, word-by-word commentary, as, for example is that of David Ross, Graham does not try to clarify portions of the text that are not directly relevant to the basic argument. For example, when Aristotle says at 261a13 that ‘In general, it appears that what comes to be is incomplete and proceeds to a principle’, many readers will no doubt find this utterly opaque. Those familiar with Aristotle’s basic doctrines will recognize that he is here referring to the completion in form of an organic substance (see Metaphysics 1019a2-4; 1050a4; 1050b7; 1077b1-9). Actually, the point is relevant to what Aristotle is claiming about the priority of locomotion to other sorts of motion in this passage, but Graham does not offer an explanation. There are in fact a number of places like this where Graham could have easily provided the requisite background. There are so many, many places in an Aristotelian text where anyone but a specialist can be stymied that it is not unreasonable to expect a commentator to risk making explicit basic points.

A different sort of criticism is perhaps made inevitable by Graham’s judicious approach. As he says in his introduction, ‘… the treatise seems to raise more questions than it answers. So too will my commentary’ (xvi). Since Graham does not intend to offer a commentary for the beginner, one would have hoped that he would have tried to advance the discussion beyond the ‘one the one hand x and on the other hand y’ stage. For the most part, he is content to recount the obvious alternatives, declining in most cases to go any further. A good example of this is the above mentioned question of whether the unmoved mover moves as an efficient or final cause or both. Graham (179-80) sets out Simplicius’ position that it is both and notes that in fact Aristotle does not actually say that the unmoved mover is an efficient cause. But there is little more than this. One might have expected that someone who had worked through Physics VIII as carefully as Graham obviously has would have at least tried to give us something new.

There are some puzzling and unfortunate gaps in the bibliography. Missing are the very important studies by J. Paulus in Revue de Philosophie (1933) and A. Pegis’s lengthy reply in Medieval Studies (1973); the important articles by K. Oehler in Philologus (1955) and J. Owens in the proceedings of the VIth Symposium Aristotelicum (1979).

In sum, this is a solid and useful piece of work but one that is unlikely to be recognized to have advanced our understanding of Aristotle’s passage from physics to theology.