DAVID TWETTEN (Marquette University)

AVERROES’ PRIME MOVER ARGUMENT

When you think of Aristotle’s arguments for a prime mover, what comes to mind ? My guess is that you think of two premises : (1) everything moved is moved by another ; and (2) there cannot be an infinite regress of things moved by another, so that a series of moved movers must end in an absolutely unmoved first mover. As we shall see, this reading of Aristotle’s argument is most unAverroean. You may think of these premises, moreover, as concluding all by themselves to Aristotle’s god, the absolutely unmoved first mover. If so, you are probably influenced by Moses Maimonides, or by Thomas Aquinas, each of whom mount four or five proofs of God’s existence, one of which appears to be a « prime mover argument » constituted by these two premises 1. Yet, for Averroes, God is not, as I argue, the immediate efficient cause of the motion of the heavens, to which these physical premises by themselves conclude 2. In fact, our stereotypical reading of the prime mover argument has probably been influenced, at least indirectly, by presentations such as those of Aquinas or Maimonides rather than Averroes’. In the interest of an accurate and philosophically coherent interpretation of Aristotle, Averroes’ version of the argument needs to be better known than it is at present. Despite its lack of influence on us, it was extremely influential in medieval and renaissance philosophy, and it still offers important insights for our reading of Aristotle’s Physics and Metaphysics. Averroes’ prime mover argument, in fact, is quite rich and complex, and I offer an introduction to this complexity, while keeping in view its philosophical and textual grounds.

Without a sense of the distinctiveness of Averroes’ prime mover argument, his cosmology must appear confused. There exist vastly different theories among the best scholars in the field as to, for example, the mode of causality of the prime mover, particularly its relation to the heavenly spheres. On one theory, efficient

1 See Maimonides’ fourth argument in Guide for the Perplexed II, 1, and Aquinas’ « first way » in Summa theologiae Ia, q. 2, art. 3.

2 On this point Maimonides and Aquinas would, of course, agree with Averroes ; see Maimonides, Guide…, op. cit., II, 4 ; cf. H. A. Wolfson, Crescas’ Critique of Aristotle. Problems of Aristotle’s Physics in Jewish and Arabic Philosophy, Cambridge (Mass.), Harvard University Press, 1929, p. 606 ; 609.

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causality or its equivalent is immanent within the heavens, so that the prime mover, as in one common reading of Aristotle, is a purely final cause « desired » by the body of each sphere 3. On this « immanent efficiency » theory, Averroes’ celestial « soul » is perhaps, as for Alexander of Aphrodisias, another term for the « nature » within each sphere, and « desire » is the sphere’s inclination toward an end that leads to motion 4.

A second theory takes the celestial « soul » to be an efficient cause which does not inhere within the heavens, and which, since it contains the end in its intellect, is identical to a separate Intelligence 5. On this « transcendent identity » theory, it still seems necessary to distinguish the first cause or God from a celestial soul 6. Accordingly, « soul » is sometimes said to be a term used imprecisely or

3 For this theory as the final stage, whether of a doctrinal evolution, or of a transformation theory in which the first efficient cause, as is found in Physics, turns out to be a final cause, as in Metaphysics Lambda, see the outstanding scholarship of M. Geoffroy in Averroes, La béatitude de l’âme. Éditions, traductions annotées, études doctrinales et historiques d’un traité d’« Averroès » par M. Geoffroy et C. Steel, Paris, Vrin, 2001, p. 74 ; 76-77 ; 248 ; and B. Kogan, Averroes and the Metaphysics of Causation, Albany (N.Y.), SUNY Press, 1985, p. 184-85 ; 195-96 ; 199-201.

4 This is Wolfson’s conclusion in his deservedly influential study ; H. A. Wolfson, « The Problem of the Souls of the Spheres from the Byzantine Commentaries on Aristotle through the Arabs and St. Thomas to Kepler », in H. A. Wolfson, Studies in the History of Philosophy and Religion, ed. I. Twersky, G. H. Williams, Cambridge (Mass.), Harvard University Press, 1973, vol. I, p. 22-59, at 43-44, reprinted from Dumbarton Oaks Papers, 16 (1962), p. 67-93 ; see also F. Carmody, Innovations in Averroes’ De Caelo, Berkeley, F. J. Carmody, 1982, p. 47-48. For B. Kogan, by contrast, « soul » turns out to be identical with the desireless Intelligence, whereas the spheres’ « desire » is a metaphor for their innate tendency ; B. Kogan, Averroes and the Metaphysics…, op. cit., p. 193-94 ; 196 ; 200-01.

5 H. A. Wolfson, Crescas’ Critique…, op. cit., p. 607 ; 609 ; H. A. Wolfson, « Notes on Proofs of the Existence of God in Jewish Philosophy », Hebrew Union College Annual, 1 (1924), p. 575-596, at 574-75 ; A. Hyman, Averroes’ De substantia orbis. Critical Edition of the Hebrew Text with English Translation and Commentary, Cambridge (Mass.) and Jerusalem, The Medieval Academy of America and The Israel Academy of Sciences and Humanities, 1986, p. 33-35 ; 113-15, n. 18-19 ; Ch. Genequand, Ibn Rushd’s Metaphysics. A Translation with Introduction of Ibn Rushd’s Commentary on Aristotle’s Metaphysics, Book Lām, Leiden, E. J. Brill, 1984, p. 40-41 ; B. Kogan, Averroes and the Metaphysics…, p. 193-94 ; M. Di Giovanni, « Averroes on the Species of Celestial Bodies », Miscellanea Mediaevalia, 33 (2006), p. 438-64, at 458-59.

6 Elijah del Medigo would be an exception in affirming that God is the first celestial soul/Intelligence, who causes motion as efficient cause qua soul and as end qua Intelligence ; see Elijah del Medigo, Quaestio de primo motore, f. 135Bb ; 136Ca, in John of Jandun (Ioannes de Ianduno), Super octo libros Aristotelis de Physico auditu subtilissimae quaestiones, Venice, 1551 ; repr. Frankfurt am Main, Minerva, 1969.

AVERROES’ PRIME MOVER ARGUMENT 11

metaphorically of the heavens 7, and the first of the Intelligences is differentiated as the only one that is a final cause 8, or as the only one that is a final cause for another Intelligence 9. A common element of each of these theories is a « thin » cosmology, the predictable result of an Aristotelian razor applied to Avicenna’s beard.

One can cite texts in Averroes to support each of these theories. Averroes frequently speaks of the celestial bodies as desiring a separate mover 10. In several places he identifies the celestial soul and its intellect/intelligence or final cause as one 11. He acknowledges that a celestial soul is ‘soul’ in an equivocal sense of the term 12. And, many passages suggest that there is only one separate final cause. Nevertheless, I maintain, without taking up the question in detail here, that both of these theories are mistaken, and that Averroes affirms two transcendent causes for each sphere: soul and separate Intelligence. In short, a « transcendent duality » theory is required by the texts and by their philosophical underpinnings 13. Contemporary scholarship will only clear itself from the forest of alternative theories, I suggest, when one’s eye is trained on the principles and arguments that drive Averroes’ conclusions. Further, we miss much of what is novel in Averroes’ cosmology, and much of his influence on subsequent theory, if we lose sight of his novel interpretation of Aristotle’s Physics. For this reason I outline his prime mover

7 H. A. Wolfson, Crescas’ Critique…, p. 607 : « The Intelligences are... called “souls” in a loose sense, by virtue of their being the cause of the motion of the spheres ». Ch. Genequand, Ibn Rushd’s Metaphysics…, op. cit., p. 40 : « “[S]ouls of the stars”... is only a less precise way of designating their intellects. This is very important, because Ibn Sīnā had based his own system on precisely such a distinction ».

8 Ch. Genequand, Ibn Rushd’s Metaphysics…, p. 41-42 ; Ch. Genequand, « Metaphysics », in S. Hossein Nasr, O. Leaman (eds.), History of Islamic Philosophy, London-New York, Routledge, 1996, vol. II, p. 783-801, at 794.

9 A. Hyman, Averroes’ De substantia orbis…, op. cit., p. 35. 10 I cite a number of passages below, n. 204. 11 I list six passages below, at n. 205-206. 12 See below, n. 65. 13 For such a theory, see P. Duhem in Le Système du monde. Histoire de doctrines

cosmologiques de Platon à Copernic, Paris, Hermann, 1913-1956, vol. IV, p. 548-54 ; H. A. Davidson, Alfarabi, Avicenna, and Averroes on Intellect. Their Cosmologies, Theories of the Active Intellect, and Theories of Human Intellect, New York-Oxford, Oxford University Press, 1992, p. 226-28 ; M. Fakhry, Averroes (Ibn Rushd) : His Life, Works and Influence, Oxford, Oneworld, 2001, p. 53-55 ; M.-P. Lerner, Le monde des sphères, Paris, Les Belles Lettres, 1996-1997, vol. I (« Genèse et triomphe d’une représentation cosmique »), p. 170. Lerner ascribes an « internal » nature to the celestial soul (p. 170-71), also an efficient causality to the First Cause, based the Short Metaphysics Commentary (p. 179).

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argument as a series of systematically defended premises. Only when the structure of Averroes’ argument is kept in mind can we properly address problems that remain in the coherence of his cosmology and in its development over the course of his writings.

In what follows, then, I itemize the key premises and stages in Averroes’ novel presentation of the whole, singling out those that drive his distinctive conclusions. I make no attempt to lay out exhaustively Averroes’ argumentation, even where it is distinctive, or his « division of the text », let alone Aristotle’s original arguments. I will say nothing here, for example, about two of Averroes’ distinctive interpretations, as crucial as they are for an understanding of the whole : regarding the relation between Physics VII and VIII, or the everlasting mobile body in Physics VIII, 1 14. In keeping with this aim, I use as my base-text the Long Commentary on the Physics (ca. 1186). This can seem an odd choice, since it is extant only in Latin and Hebrew translation and has not been critically edited 15. Nonetheless, it presents in the greatest detail Averroes’ « scientific » arguments in a non-dialectical setting 16. It also has the advantage of containing a late stage of Averroes’ thought on the issues at hand, since its composition appears to be posterior to

14 It can puzzle the contemporary reader at first that Averroes opposes Themistius’ dismissal of Physics VII and sees Books VII and VIII as forming consciously intended integral parts of one complex whole, in which each successive section builds on the previous, defending a new proposition crucial to what follows. Particularly important is that Physics VIII, 1 relies on the conclusions of Book VII to prove that the first thing moved is moved with a continuous and everlasting motion, without making redundant similar conclusions in Physics VIII, 6. See H. T. Goldstein, « Averroes on the Structure and Function of Physics VII.1 », in H. A. Wolfson and S. Lieberman (eds.), Harry Austryn Wolfson, Jubilee Volume. On the Occasion of His Seventy-fifth Birthday, Jerusalem, American Academy for Jewish Research, 1965, vol. I, p. 335-355 ; D. Twetten, « Averroes on the Prime Mover Proved in the Physics », Viator, 26 (1995), p. 107-134, at 111-114.

15 I use the Junta edition (except for part of Physics VIII, 10) : In libros Physicorum Aristotelis, in Aristotelis Opera cum Averrois Commentariis, Venetiis, apud Junctas, 1562 ; repr. Frankfurt am Main, Minerva, 1962, vol. 4. For information on its accuracy, see G. Guldentops, « Introduction to the Edition of Averroes, Physica, VIII, Chs. 78-79 & 86 », in Averroes Latinus. A New Edition, Recherches de Théologie et Philosophie médiévales: Bibliotheca 4 (Leuven, 2002), xix-xxii, 1-16 ; S. Harvey, « The Hebrew Translation of Averroes’ Prooemium to His Long Commentary on Aristotle’s Physics », American Academy for Jewish Research, 52 (1985), p. 55-84, at 56-59 ; H. Schmieja, « Der Physikkommentar von Averroes in der Editio Iuntina : Die mittelalterlichen Quellen für Buch 6, Text 87 », Bulletin de philosophie médiévale, 43 (2001), p. 75-93.

16 For an outstanding reconstruction of Averroes’ theoretical sciences using the Tahāfut at-Tahāfut as the base-text, see B. Kogan, Averroes and the Metaphysics…

AVERROES’ PRIME MOVER ARGUMENT 13

that of his other physical works (including many « personal » writings) that are not Long Commentaries. I cite parallels to the other works, without attempting to be exhaustive, in order to indicate the reliability and historicity of the doctrines of the Long Commentary on the Physics in Latin. The advantage of this approach is that Averroes’ thought, once seen « writ large », can then be discerned, at least in germ, in the shorter works, for which the Long Commentary provides a framework of the whole 17. The disadvantage of this method is that it can suggest that Averroes had worked out from the outset a completed system in which he had considered exhaustively all of the problems of his contemporary exegete. Still, some sense of the development of his thought can be gathered from the parallel texts, and I draw attention to points at which incoherencies, and therefore the need for interpretative conjecture, remain. In my view, Averroes’ prime mover argument cannot be taken as complete without appeal to texts from the Long Commentary on the Metaphysics and the treatises gathered under the title De substantia orbis 18.

Stage I : Physics VII-VIII, 5 : The Arrival at a First Self-Mover

Let me begin by saying that we are not generally wrong to take there to be two main premises of the prime mover argument :

17 For an account based on the Epitomē De caelo, see G. Endress, « Averroes’ De caelo : Ibn Rushd’s Cosmology in his Commentaries on Aristotle’s On the Heavens », Arabic Sciences and Philosophy, 5 (1995), p. 9-49.

18 For convenience, I cite the seven treatises that constitute the Renaissance Latin edition of the « De substantia orbis » as seven chapters under this title. Yet, it is uncertain whether Averroes composed or even grouped these as one, and the Barnamay in the Escorial itemizes the Arabic treatises separately. See A. Hyman, « The Composition and Transmission of Averroes’ Ma’amar be-‘Eêem ha-Galgal », in M. Ben-Horin, B. D. Weinryb, and S. Zeitlin (eds.), Studies and Essays in Honor of Abraham A. Neuman, Leiden, E. J. Brill, 1963, p. 299-307 ; D. Wirmer, « Questions in Physics/Philosophy of Nature/Averrois Opera/Averroes-Database », Thomas-Institut, Cologne (last updated : 08/31/2004) <http://www.thomasinst.uni-koeln.de/averroes/averdat28.htm#remark>. I differentiate references to A. Hyman’s edition of the Hebrew (= De substantia orbis : Hebrew) from the best modern edition of the old Latin (Michael Scot ?) translation, found in Alvaro de Toledo, Commentario al « De substantia orbis » (= De substantia orbis Alonso), ed. M. Alonso, Madrid, Consejo Superior de Investigaciones Científicas, 1941. For the Latin of « Chapters » 6-7 (translated by Abraham of Balmes from the Hebrew), I cite the Junta ed. (= De substantia orbis Junta), in Aristotelis Opera cum Averrois Commentariis, ed. cit., vol. 9.

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(1) Everything moved is moved by something (ÍpÒ tinow ; ]^ _` ab Phys. VII, 1 ; VIII, 4) 19.

(2) There cannot be an infinite series of moved movers, but a series must end in a first mover (Phys. VII, 1 ; VIII, 5).

Aristotle’s first version of the prime mover argument, in Book VII, Chapter 1 of the Physics, is comprised by arguments proving these two premises alone 20. Similarly, Aristotle’s version in Physics VIII has these two premises at its core, although they are surrounded by a number of other premises. Why, then, do I insist that Averroes’ distinctive reading of these premises has been missed ?

In simplest terms, the distinctive feature of the Averroean reading is that what is concluded from these two premises, both in Book VII and in Book VIII of the Physics, must be some sort of self-mover. This will be clearest if we look at the Averroean reading of Premise (2) :

(2.1) There cannot be an infinite series of moved movers, but a series must end in a first mover that is moved by itself.

Averroes thus adds to Premise (2) that the first mover must be « moved by itself » 21 (ex se ; cd ]efg a^ ; sometimes a^ cgذا ) 22. For the Commentator, the

19 I refer to the Arabic at Physics VII, 1, 241b34, in Aristotle, AÔ-T{abÐÝa, ed. A. Badawī, Cairo, Al-Dar al-Qawmiyyah lil-¬iba‛a wa-l-Nashr, 1964-1965, vol. II, p. 733.

20 This fact provides the most important ground in Aristotle’s text for our stereotypical reading of the prime mover argument.

21 Averroes, In libros Physicorum…, VII, 1, t.c. 3, f. 308IH ; VII, 2, t.c. 9, f. 311L ; VIII, 2, t.c. 19, f. 354G ; VIII, 3, t.c. 21, f. 356H ; VIII, 5, t.c. 33, f. 372F ; t.c. 34, f. 373AB, E ; t.c. 36, f. 375F ; VIII, 6, t.c. 45, f. 385E, G, I. See also Averroes, Epitome in Physicorum libros, edidit Josep Puig, Madrid, Instituto Hispano-Arabe de Cultura-Consejo Superior de Inverstigaciones Científicas, 1983, VII, 1, p. 117, 1-4 ; VIII, 4, p. 139, 10-11 ; VIII, 5, p. 140, 6-12 ; Averroes, Al-MaqÁla al-sÁbiÝa wa-l-×Ámina min al-samÁÝ al-ÔabÐÝÐ li-ÞArisÔÙ (= Questions in Physics VII), p. 225, 10-11 ; 229, 14-15 ; 234, 25-235, 3 ; 235, 9-10, 13-17 ; 238, 7-8, 12-18 ; 239, 7-8, in Averroes, MaqÁlÁt fÐ l-manÔiq wa-l-Ýilm al-ÔabÐÝÐ, ed. J. al-ÝalawÐ, Casablanca, Dār al-Našr al-maġribiyya, 1983, p. 225-243 (I add references to the translation from Hebrew in Averroes’ Questions in Physics : From the Unpublished Sêfer ha-derûšîm ha-tib'îyîm, trans. H. T. Goldstein, Dordrecht, 1991, q. 7, ¶ 2, 10, 25, 27-28, 33-35, 37) ; Tahafot at-Tahafot, texte arabe établi par Maurice Bouyges, s.j., Beirut, Dar el-Machreq, 1930, 14, p. 471,11-13 ; De substantia orbis : Hebrew, chap. 6, 98-109.

22 For the Arabic, see below, n. 25. As is noted by R. F. Hassing and E. M. Macierowski, « Latin Averroes on the Divisibility and Self-Motion of the Elements », Archiv für Geschichte der Philosophie, 74 (1992), p. 127-157, at p. 131, n. 14, « ex se » sometimes refers (even in the Latin of the Long Physics Commentary, though it is generally quite accurate and consistent ; see Averroes, In libros

AVERROES’ PRIME MOVER ARGUMENT 15

prime mover that Aristotle proves in Physics VII and VIII is, in the first instance, a self-moved mover 23.

A. Philosophical Evidence

The evidence that supports Averroes’ reading is both textual and philosophical. I begin with the philosophical evidence. Averroes and the tradition under his influence give very creative philosophical grounds, not found in Aristotle, for their reading. In reality, Averroes develops his reading under the influence of Ibn Bājja, from whom he draws most of its important elements 24. The essence of this reading consists in a proposition that is not found expressly in Aristotle :

(3) Every external mover must be a moved mover 25.

In other words, every mover that is not part of a self-moving whole, but that moves something other than itself must be a mover that is moved. Therefore, it cannot be an unmoved mover.

Physicorum…, VII, 1, t.c. 2, f. 307K), not to self-motion, but to a thing moved per se or kaq’au(to& (a[x«\^ or ¹b[x«\^).

23 I say « in the first instance », because further analysis will show that every self-moved mover is moved by a part which unmoved. Hence, it would be more accurate to say that the prime mover that Aristotle proves in Physics VII and VIII, 5 is, for Averroes, the (unmoved) part of a self-moved mover.

24 Cf. P. Lettinck, Aristotle’s Physics and Its Reception in the Arabic World : With an Edition of the Unpublished Parts of Ibn Bājja’s Commentary on the Physics, Leiden, E. J. Brill, 1994, p. 615-622.

25 Averroes, In libros Physicorum…, VII, 1, t.c. 3, f. 308I ; t.c. 4, 309A ; VIII, 2, t.c. 19, f. 354G, where Premise (3) is ascribed to Physics VII ; VIII, 5, t.c. 34, f. 373BC, E. Cf. Averroes, Epitome in Physicorum libros, ed. cit., VII, 1, p. 117, 1-2 ; VIII, 5, p. 139, 17-140, 3. The Latin speaks of « intrinsic » versus « extrinsic » movers. The Arabic nearly always uses a preposition with an adverb, speaking of a mover as رج \r µ¯ ¦zo¯ (e!cwqen) versus a mover (Averroes, Questions in Physics VII, ed. cit., p. 225, 10-11 [¶ 2]) – or, usually, what is moved (¦zoc¯) – as ¹Î\¤¬b µ¯ (Averroes, Epitome in Physicorum libros, VIII, 4, p. 138, 1-9 ; p. 139, 7-12 ; p. 139, 16-140, 3 ; Averroes, Questions in Physics…, VII, p. 234, 23-235, 3 ; p. 235, 9-10, 13-17 ; p. 238, 7-8, 12-18 ; p. 239, 7-8 [¶ 24-25, 27-28, 33-35, 37]) ; or as ¹b[w µ¯ (Averroes, Epitome in Physicorum libros, VII, 1, p. 117, 4 ; VIII, 4, p. 138, 8-9 ; Averroes, Questions in Physics VII, p. 228, 21-229, 2 ; p. 229, 14-15, 18-19 ; p. 234, 23-235, 3 [¶ 9-11, 24-25]) ; or as ¹� ³ µ¯ (ibid., p. 236, 20-21).

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Notice the effect of Premise (3) when applied to a series of movers as is imagined in Premise (2). Whenever a prior mover in the series is external to what it moves, it will in turn be moved by a prior mover, since according to Premise (1), everything moved is moved by something 26. As Averroes himself observes, if all movers are external, there will result an infinite series of prior movers, simultaneous with the thing moved with which the series began27. But this is contrary to Premise (2) 28. An impossible consequence is avoided, argues Averroes, only if there is a first thing that is moved, not by an external, but by an internal mover 29. And, this is precisely Averroes’ conclusion: the first mover must be a self-mover. As he sees it, this is the fundamental argument, found in both Physics VII and VIII, for a prime mover, and this mover is a prime self-mover.

But why does Averroes think that Premise (3) is true, that every external mover must be a moved mover ? In one place, Averroes gives a hint :

(4) An external mover moves in place, since it is a body 30.

26 One might have expected to find Averroes in the Physics commentaries affirming immediately « Everything moved is moved either by itself or by another », as he does elsewhere : Averrois Cordubensis commentum magnum super libro De celo et mundo Aristotelis, ex recognitione Francis James Carmody †, in lucem edidit Rüdiger Arnzen, Editioni praefatus est Gerhard Endress, Leuven, Peeters, 2003, IV, 3, t.c. 25, vol. II, p. 707, 120-122 ; see also Averroes, Tahafot at-Tahafot, ed. cit., 14, p. 471, 5-6 ; cf. ibid., p. 470, 5-8.

27 In libros Physicorum…, VII, 1, t.c. 3, f. 308IH ; t.c. 4, 309AB ; VIII, 2, t.c. 19, f. 354G ; VIII, 5, t.c. 35, f. 374B ; t.c. 39, f. 379E ; Epitome in Physicorum libros, VII, 1, p. 117, 1-12 ; VIII, 5, p. 139, 13-140, 12 ; Commentum magnum super libro De celo et mundo, III, 2, t.c. 20, ed. cit., vol. II, p. 525, 36-53 ; Questions in Physics VII, p. 228, 21-229, 15 ; p. 234, 25-235, 3 (¶ 9-10, 25).

28 I will not attempt here to lay out Averroes’ defense of Premise (2). Note, however, that neither Averroes nor Aristotle excludes an infinite series of temporally prior movers which are not necessary as causes of the motion with which the reasoning began while it occurs. Both Averroes and Aristotle affirm the existence of a temporally infinite series of motions and their causes. Cf. Averroes’ distinction between an infinitude of causes ordered accidentally versus essentially ; In libros Physicorum…, VIII, 6, t.c. 47, f. 388I-L ; Questions in Physics VII, p. 235, 5-16 (¶ 26-27) ; Tahafot at-Tahafot, 4, p. 267-69 ; De substantia orbis : Hebrew, chap. 6, 99-102.

29 To the texts cited above, n. 27, we may add In libros Physicorum…, VIII, 5, t.c. 34, f. 373BC ; t.c. 35, f. 374C ; t.c. 44, f. 385BC ; VIII, 6, t.c. 50, f. 390GH ; Epitome in Physicorum libros, VIII, 5, p. 141, 12-16 ; Questions in Physics VII, p. 235, 13-17 (¶ 27).

30 Averroes, In libros Physicorum…, VIII, 5, t.c. 34, f. 373E. Cf. ibid. VII, 1, t.c. 3, f. 308I, where what is moved in place is said to have an external mover, as is evident in bodies moving other bodies in place.

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Elsewhere, he says simply, in a résumé of Physics VII :

(4.1) Every mover in place is a body 31.

But, again, why think that every external mover is a body ? Averroes derives this proposition from his reading of Physics VII, specifically of Chapters 2-3. The Stagyrite’s project here is to shore up his defense in Physics VII, 1 (242a49-243a31) of Premise (2), by showing, inductively for all four kinds of motion, that every mover is together with what it moves. If so, then the series of moved movers that is imagined in Physics VII, 1 will be infinite in magnitude. As a result, this infinite magnitude will be traversed in a finite time when the body is moved with which the argument starts – a traversal shown in Physics VI, 7 (238a20-31) to be impossible.

Averroes apparently takes Chapter 2-3 to establish a more ambitious claim than is explicit in the text. Aristotle begins with things moved in place, which he divides exhaustively into what is moved by itself – in which it is obvious that mover and moved are together – and what is moved by another 32. Aristotle presumably can assume that the mover in the latter case is corporeal, since he is trying to prove (as is clear, in any case, by the end of Physics VIII) that at least one mover is incorporeal. For Averroes, however, when Aristotle « reverts » to the alternative case of extrinsic movers, he shows that in every case the mover is together in the same place with what it moves 33. By contrast, an intrinsic mover is not a body, but the form of a body, which is attributed to place because the body that it moves is in place 34. Thus, Averroes takes Physics VII, 2-3 to establish a proposition that we may summarize as follows :

(4.2) Every external mover is a body together in place with what it moves 35.

31 Commentum magnum super libro De celo et mundo, III, 2, t.c. 20, p. 527, 89. 32 Aristotle, Physica, ed. W. D. Ross, Oxford, Clarendon Press, 1950, VII, 2, 243a11-16 ;

see Averroes, In libros Physicorum…, VII, 2, t.c. 9, f. 312D ; t.c. 10, f. 314EF. 33 Averroes, In libros Physicorum…, VII, 2, t.c. 9, f. 312D ; t.c. 10, f. 314C-F. Cf. ibid., VII,

1, t.c. 3, f. 308E-H. 34 In libros Physicorum…, VII, 2, t.c. 9, f. 312D-F. 35 Cf. Epitome in Physicorum libros, VII, 1, p. 117, 7-9, according to which a « mover in

place », if external, moves by contacting the mobile and also by being moved. Through this contact there results a single infinite magnitude.

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And so, if all external movers are bodies together with what they move, and all bodies are moved as they move 36, then Premise (3) follows : Every external mover must be a moved mover. Again, if every external mover is a moved mover, then either there results an impossibility, the traversal of an infinite magnitude, or there will be a first thing moved by itself, by an intrinsic mover.

B. Textual Evidence

Notice that by maintaining that every external mover is a body, Averroes gives no serious consideration to the possibility that an external mover could be incorporeal. Some may have imagined that such an external incorporeal mover was the very aim of the argumentation of Physics VII and VIII 37. Nonetheless, there is a surprising amount of textual evidence in Aristotle for Averroes’ reading of the Physics as concluding to a first self-mover. Averroes’ Premises (3) and (4) give an at least coherent explanation of Aristotle’s otherwise unaccounted for presumption in favor of a first self-mover. But to what textual evidence do I refer ?

First, Aristotle twice clearly affirms souls of the heavenly spheres in his De caelo 38, and on several other occasions he alludes to such a doctrine. Second, in the best version of Physics VII, 1 (textus primus, mss bcjy in Ross), Aristotle concludes, literally : « There must be a ‘first’ causing motion and moved » 39. Averroes, who comments on the translation of this version – although he also is at least partially aware, through the Arab commentators, of

36 Aristotle, Physics III, 1, 201a23-25 ; III, 2, 202a3-8. Cf. Averroes, In libros Physicorum…, VIII, 5, t.c. 35, f. 374DE ; t.c. 37, f. 376H ; Epitome in Physicorum libros, VII, 2, p. 120, 14-15.

37 Averroes’ thinking on the priority of self-motion is not limited to his interpretation of extrinsic movers as bodies in Physics VII, 1. He elsewhere holds that whenever a body is moved by a mover that does not exist in it, that is, by an external mover, it is moved violently, and therefore not with an infinite motion ; Commentum magnum super libro De celo et mundo, III, 2, t.c. 27, p. 549, 25-28 (where reference is also made to Physics VII).

38 Aristotle, Du ciel, texte établi et traduit par Paul Moraux, Paris, Les Belles Lettres, 1965, II, 2, 285a27-31 ; II, 12, 292a19-b33.

39 Aristotle, Physics VII, 1, 242b71-72 : « énãgkh [...] e‰na¤ ti pr«ton kinoËn ka‹ kinoÊmenon ».

AVERROES’ PRIME MOVER ARGUMENT 19

the textus alter – naturally understands Book VII to conclude to a first thing moved that is also its own mover, a first that is self-moved 40.

Third, and most importantly, let’s turn to Aristotle’s own wording of the conclusion of the first two arguments of Physics VIII, 5. Admittedly, Aristotle expresses himself hypothetically : « ... if the first mover is moved, but [is] not [moved] by another, it is necessary that it be moved by itself » (Phys. VIII, 5 256a20-21). Similarly, in the second argument, he concludes, « If this [first mover] is moved, and there is not another moving it, it is necessary that it move itself » (Phys. VIII, 5 256a33-b1). But notice Aristotle’s further inference in the same conclusion : « so that... either immediately that which is moved is moved by what moves itself, or at some time we arrive at such » (256b1-3). Unless we interpret this latter inference hypothetically, as governed by the original conditional clause, Aristotle seems to be affirming that his argument arrives ultimately, whether directly or indirectly, at a first self-mover.

In fact, in Aristotle’s subsequent preliminary résumés of his prime mover argument, there is confirmation for this arrival at a first self-mover. First, on three occasions in Chapters 5 and 6 he reports a disjunctive conclusion as part of the reasoning : the argument arrives at either at a first that is unmoved (at rest) or moved by itself. Second, on at least four occasions, Aristotle affirms that there is a first self-mover as a principle of all other things moved, and he even gives the reason why.

Consider the first of Aristotle’s three statements of a disjunctive conclusion of the prime mover argument, which concludes the first half of Chapter 5 :

[S]o, either the first thing moved will be moved by what is at rest, or it will move itself. But, certainly, were it requisite to investigate whether what moves itself or what is moved by another is the cause and principle of motion, everyone would affirm the former. For, what is per se is always a cause prior to what is a being per aliud and is itself [a cause] 41. So, beginning again, we must investigate whether something moves itself, how and in what way (Physics VIII, 5, 257a26-33).

40 Averroes, In libros Physicorum…, VII, 2, t.c. 9, f. 311L. Note that the Junta editions, however, give the textus alter as the text of Aristotle, Physics VII, 1-3 on which Averroes comments. On the Arabic translations of the Physics and the versions known to Averroes, see P. Lettinck, Aristotle’s Physics and Its Reception…, op. cit., p. 1-3 ; 12 ; 14 ; 32 ; 180-84 ; 514 ; 516-18 ; 546.

41 I translate Ross’ text, found in mss EK (see also Themistius), and followed, apparently, by Averroes, In libros Physicorum…, VIII, 5 (257a30-31), t.c. 39, f. 379FG.

DAVID TWETTEN 20

Aristotle begins this passage with a disjunctive statement of his conclusion thus far, a statement that includes a first self-mover on one side of the disjunction. He then accompanies this statement with a brief but marked argument that the first thing moved must be self-moved : because « what is through itself » is prior to what is through another.

The importance of this argument is confirmed by the fact that Aristotle bases his subsequent investigation of self-movers in Chapters 5 and 6 on this conclusion. The second half of Chapter 5 proceeds to prove that no self-mover can move itself strictly speaking, that is, as a whole moving the whole (Physics VIII, 5, 257a33-258b4). Instead, all self-motion occurs only insofar as one part of the whole is moved by another – the latter of which remains unmoved. At the end of this discussion, Aristotle offers the second statement of his disjunctive conclusion, which closes Chapter 5 :

From these [arguments] it is clear, therefore, that the first mover is unmoved (ék¤neton). For, that which is moved – and which is moved by something – stops either straightway at a first that is unmoved, or at what is moved but which moves and stops itself. In each case it follows that the first mover for each and every thing moved is unmoved (Physics VIII, 5, 258b4-9) 42.

Once again, Aristotle affirms here a self-moved mover on one side of a disjunction.

Now, a disjunctive proposition affirms each disjunct by itself only hypothetically. Nevertheless, in four places Aristotle affirms unconditionally that there is a first principle among all things moved that is, not moved by another, but self-moved. We have already seen the first of these passages, which is accompanied by an argument for this affirmation, at Physics VIII, 5, 257a27-31. The second passage offers an express backreference to this passage (and the other two passages at least suggest a reference to it). This second passage, which constitutes another résumé of the entire argument (this time in the midst of Chapter 6), also contains the third and final statement expressing the disjunctive character of Aristotle’s reasoning :

[...] having established that each and everything moved is moved by something, and that this [mover] is either unmoved (ék¤neton) or moved, and that what is moved is

42 Aristotle’s affirmation of an unmoved mover as part of a self-moved mover, coming on the heels of his refutation of strict self-motion, is important for Averroes’ reading ; see below at n. 42-46.

AVERROES’ PRIME MOVER ARGUMENT 21

always either [moved] by itself or by another, we went on to accept that among things moved, there is a principle of what is moved, on the one hand, that moves itself; [there is a principle] of all things, on the other hand, that is unmoved (ék¤neton) (Physics VIII, 6, 259a30-b1).

The third affirmation of a first self-mover, by contrast, comes in Chapter 7 : « [W]e say that this is the principle of things moving and moved, and the first among things moved : what moves itself » (Physics VIII, 7, 261a25-26). Finally, there is a fourth affirmation in the De motu animalium. Although it is found outside the Physics, this passage is both dependent upon and entirely consistent with what we have seen of the Physics’ argumentation thus far :

Now, it was previously determined that a) what moves itself is the principle of the other motions, whereas [the principle] of this [what moves itself] is what is unmoved (ék¤neton), and b) it is necessary that the first mover be unmoved (ék¤neton)... 43

It turns out, then, that there are strong textual grounds in Aristotle for Averroes’ reading of Physics VII and VIII alike as concluding to the existence of a first mover that is self-moved, of which a part is unmoved.

How, though, does Averroes interpret Aristotle’s disjunctive statements of his reasoning, concluding either to an unmoved mover or to a first self-moved mover ? For the Commentator (without explicitly naming them « disjunctive »), such statements are preliminary conclusions that disappear by the end of Chapter 5 44. Why ? On Averroes’ reading of the statements, each disjunct envisions a first thing moved that is a self-moved, as a consequence of Premise (3) : Every external mover must be a moved mover. Hence, a properly expanded reading of the disjunctive statement would read :

(5) The first thing moved is self-moved through a motion-causing part that is either unmoved or itself self-moved 45.

The project of the second half of Chapter 5, in Averroes’ eyes, then, is to consider and exclude through reasoning the second disjunct : the possibility that the mover that is the motion-causing part of the first self-mover is itself self-moved. For Averroes, this possibility results from Aristotle’s testing and

43 De motu animalium I, 698a7-10. 44 See Averroes, In libros Physicorum…, VIII, 5, t.c. 44, f. 385BC (on 258b4-9). Thus, the

one disjunctive statement in Chapter 6 would be a mere backreference to Chapter 5. 45 See In libros Physicorum…, VIII, 5, t.c. 39, f. 379E ; t.c. 40, f. 385AB (on 257a31-33).

DAVID TWETTEN 22

excluding Plato’s hypothesis that every mover is moved, so that even the primary purely immaterial movers (including the parts of Aristotelian self-movers) are self-moved 46. By excluding this possibility, and by collapsing the disjuncts into a single affirmation, Averroes’ Aristotle affirms a first thing moved that is self-moved through an unmoved and immobile (versus self-moved, as for Plato) motion-causing part. Again, this project is complete by the end of Chapter 5.

As a result of this interpretation, Averroes can explain away many statements of Aristotle that are apparently inconsistent with his reading of the Physics as concluding to a first self-mover. On multiple occasions within some seven passages, Aristotle speaks of Physics VIII’s argumentation as concluding to a first unmoved or immobile mover 47. For Averroes, this mover can only be the motion-causing part of a self-moving whole 48. Let us turn next to how Averroes understands this prime mover in the rest of the Physics.

Stage II : The Nature of the Prime Mover Proved by the End of Physics VIII, 6

The distinctiveness of Averroes’ reading of the prime mover argument stems from his conclusion as a physicist that change is globally unexplainable unless traced to a first mover that is part of a self-moving whole. On Averroes’ reading, Chapter 6 of Physics VIII, far from transcending or explaining away this first self-mover – whose existence was soundly established in Stage I – largely amounts to a clarification of its nature. But this reading appears to face an obstacle in a famously difficult passage.

A. The Problem Posed by Aristotle’s Denial of Per accidens Self-Motion

Everyone agrees that in Chapter 6, Aristotle starts with the prime mover arrived at in Chapter 5 and establishes, first, that it is everlasting, not moved by

46 In libros Physicorum…, VIII, 5, t.c. 39, f. 379E ; t.c. 40, f. 385B-F ; t.c. 42, f. 381I. Cf. also Commentum magnum super libro De celo et mundo, IV, 3, t.c. 22, p. 696, 154-161.

47 Aristotle, Physics VIII, 5, 256b23-27 ; VIII, 6, 258b11-16 ; VIII, 6 258b32-a13 ; 259a20-24, a28-b1 ; 259b20-24 ; 259b31-260a6 ; 260a14-19.

48 See especially Averroes, In libros Physicorum…, VIII, 5, t.c. 36, f. 375F ; t.c. 37 (256b14-27), f. 376KL ; t.c. 40, f. 380AB ; t.c. 44, f. 385BC ; VIII, 6, t.c. 46, f. 386H (on 258b13-14) ; t.c. 50, f. 390GH (on 259a30-b1).

AVERROES’ PRIME MOVER ARGUMENT 23

substantial change, and, second, that it is not moved even accidentally as are terrestrial animals. This second point is particularly important for Averroes’ reading of the Physics as concluding to a first self-mover 49. For, at first glance, it would appear that a prime mover that moves itself is precisely what Aristotle is dismissing as a possible source of cosmic motion. Animals, he says, are moved by what surrounds them, and their desires are effected by changes in their surroundings so that they do not always act in the same way 50. Similarly, the first mover within the animal, namely, the soul, moves itself indirectly : it moves the body, which in turn carries the soul wherever it goes 51. It does not seem that a mover that is accidentally moved in this way could cause continuous, everlasting motion 52. What allows Averroes to think that Aristotle is not rejecting celestial ensoulment here ?

The answer to this question lies in Averroes’ reflections on an important digression by Aristotle, where he clarifies that he does not intend to exclude all per accidens motion from the heavens. Notice Aristotle’s first explicit reference to the heavens in the prime mover argument of Physics VIII, 4-6 :

But being per accidens moved by itself and by another are not the same thing. For, [being per accidens moved] by another belongs also to some principles of things in the heaven, [namely, to] as many [of these] as are borne along (f°retai) with many locomotions; whereas the other [that is, being per accidens moved by itself, belongs] only to corruptible things (Physics VIII, 6, 259b28-31).

How do we understand this obscure passage ? It is evident that Aristotle refers to the celestial spheres. For, in his cosmology, subordinate spheres are per accidens borne along by the same revolutions as are possessed by outer spheres. Thus, although each sphere is per se moved with only the one motion caused by its proximate or immediate mover 53, the innermost sphere within

49 In fact, as Averroes apparently interprets Aristotle’s division of the text, the second half of Physics VIII, 6 (beginning at 259a20) initiates a second argument, following upon that of Physics VIII, 1-6 up to this point, that there is an everlasting unmoved mover ; In libros Physicorum…, VIII, 6, t.c. 50, f. 390CD.

50 Aristotle, Physics VIII, 6, 259b1-20. 51 Aristotle, Physics VIII, 6, 259b20-28. 52 Recall Averroes’ reading of Physics VIII, 1’s conclusion ; see above, n. 14. 53 For « ultimate » versus « proximate mover » (`¿z¤«[ ¦zo°«[), see Averroes, Tafsīr mā

ba‘d aì-ìabī‘at (« Grand Commentaire » de la Métaphysique), texte arabe inédit établi par Maurice Bouyges, s. j., 1 vol. « Notice » + 3 vol., Beyrouth, Imprimerie catholique, 1938-1952 ; repr. Dar el-Machreq, 21973, Λ, 5, t.c. 24, p. 1529, 6-1530, 3.

DAVID TWETTEN 24

each « nest », which carries a planet, is per accidens moved also by all the outer spheres within the same « nest ». As a result, invisible spheres can account for the multiple motions displayed by each planet.

At the same time, this passage creates great difficulty for Averroes’ reading of Chapter 6 as referring to spheres that are self-moved by what are elsewhere called « souls ». How can Aristotle exclude from the heavens only per accidens motion that is caused by itself, not per accidens motion caused by another ? If some sphere-souls are per accidens moved by outer spheres, it seems that they must also be per accidens moved by themselves.

B. The Distinction between Inherent and Non-Inherent Souls

In answer, Averroes affirms three crucial distinctions. First, he distinguishes the relation of the mover to its body in celestial versus in terrestrial self-movers. The celestial mover is, according to the Latin, « not constituted through its subject » ; non constituitur per subjectum 54. We are fortunate to have the exact Arabic equivalent for Averroes’ phraseology in the Epitomē Physics. Unlike in the case of a terrestrial soul, says Averroes, in the case of a celestial mover « there is no subsistence for it in the subject » ; u{ |55. The Long Commentary on the Physics elaboratesام لy c[لuvuwع

54 Averroes, In libros Physicorum…, VIII, 6, t.c. 52, f. 392L. See also ibid. f. 393BC ; t.c. 51, f. 391KL ; VIII, 5, t.c. 44, f. 384LM ; Commentum magnum super libro De celo et mundo, I, 2, t.c. 5, p. 13, 32-34 : non consistentem per materiam [naturam : Carmody] ; De substantia orbis Alonso, chap. 1, p. 108, 19, and chap. 3, p. 218, 11-12 : non constitutur per rem motam. The doctrine is also found in Averroes’ De separatione primi principii, p. 108, 20-24 ; p. 112, 12-13 ; p. 116, 4-11 ; p. 120, 10-12 ; cf. p. 110, 17-21, in C. Steel, G. Guldentops, « An Unknown Treatise of Averroes against the Avicennians on the First Cause. Edition and Translation », Recherches de théologie et philosophie médiévales, 64,1 (1997), p. 86-135.

55 Epitome in Physicorum libros, VIII, 6, p. 146, 13 ; also l. 5. See also Tahafot at-Tahafot 4, p. 271, 7-8 : « As for the soul, there is no subsistence for it in this body... » ; ±�k«[ [x¸^ ام½£ \¸« Ä« ; see also Questions in Physics VII, p. 239, 9 (¶ 37). Cf. ±Î\£ ; ibid. p. 236, 1, 5-7 (¶ 29). Arabic normally uses qiwām, for example, for the way accidents are in substances ; see M. Alonso, « ‘Al-qiwam’ y ‘al-anniya’ en las traducciones de Gundisalvo », Al-Andalus, 22 (1957), p. 377-405. The Hebrew translation of the De subst. orb. usually uses a phrase equivalent to the Arabic : הדעמי בנושא in ,להם De substantia orbis: Hebrew, chap. 1, 158-160 ; see chap. 2, 36 ; 3, 24 and 29, 40, 68, 101 ; 6, 17 (for a rendering with participle or verb, see ibid. chap. 1, 163 and 167, 187, 190 ; 6, 145 ; cf. 1, 30 ; for the etymological equivalent of the Arabic, see ibid. 3, 102: מקויים ; and ibid. chap. 32, 27, 34, 42, 70, 106, Ibn Ayyub trans.: קיום ; also 1, 172: קימות). For Latin equivalents of the noun phrase, see, in addition to

AVERROES’ PRIME MOVER ARGUMENT 25

Averroes’ doctrine as follows : in the case of terrestrial self-movers, their soul is the form of the body which is their matter ; whereas celestial movers are not « defined through their subject », but are « entirely separate in being and definition from what they move » 56. In a word, Averroes’ celestial souls are not hylomorphic forms that actualize matter 57. On his account, celestial bodies, unlike terrestrial, have no « prime matter » 58, but their matter is already actualized in three dimensions without a substantial form 59. Otherwise, the heavens would be composites of matter and a form actualizing it, and therefore would be subject to generation and corruption 60. It follows that since celestial souls are forms that do not inhere in the body that they move, they are not carried along with the celestial body. Otherwise, again, according to Physics VIII, 6, they would be per accidens self-moved and could not cause everlasting motion 61.

In libros Physicorum...VIII, 10, t.c. 79, f. 427AB, quoted below, in n. 74, ibid. 1.7 (190b6), t.c. 63, f. 38F : « ideo [corpus caeleste] caret forma, quae sustentatur per hoc subiectum, et fuit necesse ut forma eius esset liberata ab hoc subiecto, et ut non haberet constitutionem per corpus caeleste » ; De substantia orbis, chap. 2, p. 137: « declaratum de formis celestibus ipsas non habere constitucionem per corpora celestia ». Cf. De separatione…, p. 114, 6-8: sustentamentum ; De substantia orbis Junta, chap. 7, f. 13H : consistentia.

56 In libros Physicorum... VIII, 5-6, t.c. 37, f. 376L ; 44, f. 377A, ; 52, f. 384LM, 392L ; cf. t.c. 52, f. 393C, where definitione should perhaps be read for dispositione ; also VIII, 4, t.c. 28, f. 366FG. That the celestial subject is defined through its form, but not vice versa, see De separatione…, p. 112, 8-15.

57 De separatione…, p. 110, 13-25 ; p. 116, 4-17. 58 De substantia orbis: Hebrew, chap. 1, 46-53 and 98-101, 124-132, 187-188 ; 2, 2-8 ; 3,

100-106 ; cf. chap. 6, 133-147 ; De separatione…, p. 110, 1-112, 10 ; 114, 28-116, 19 ; Commentum magnum super libro De celo et mundo, II, 6, t.c. 38, p. 343, 96-97 ; Tafsīr mā ba‘d aì-ìabī‘at Η, 4 (1044 b 6-8), t.c. 12, p. 1077, 5-1078, 8. See also A. Hyman, « Aristotle’s ‘First Matter’ and Avicenna’s and Averroes’ ‘Corporeal Form’ », in Wolfson, Jubilee Volume, vol. I, p. 385-406 ; S. Donati, « La dottrina di Egidio Romano sulla materia dei corpi celesti : Discussioni sulla natura dei corpi celesti alla fine del tredicesimo secolo », Medioevo, 12 (1986), p. 229-280, at 233-43 ; G. McAleer, « Augustinian Interpretations of Averroes with respect to the Status of Prime Matter », Modern Schoolman, 73 (1996), p. 159-72 ; M. Di Giovanni, « Averroes on the Species of Celestial Bodies », p. 440-43.

59 De substantia orbis : Hebrew, chap. 2, 29-30, 47-51 ; 5, 10-14 ; De separatione…, p. 126, 4-28. 60 De substantia orbis: Hebrew, chap. 2, 186-188 ; De separatione…, p. 110, 26-114, 6 ; cf.

Questions in Physics VII, p. 241, 5-7 and 14-16 (¶ 44, 45) ; q. 9, ¶ 5 ; Commentum magnum super libro De celo et mundo, II, 1, t.c. 3, p. 274-275, 22-24 and 31-40 ; De substantia orbis Junta, chap. 7, f. 14E.

61 In addition to the Long Commentary on the Physics, see De substantia orbis : Hebrew, chap. 2, 36-41 ; 6, 106-111 ; Questions in Physics VII, p. 239, 7-11 (¶ 37) ; De separatione…, p. 112, 26-114, 6.

DAVID TWETTEN 26

C. The Distinction between What is Essentially versus Accidentally Self-Moved

It might seem, then, that the mover of the heavens should not be called a soul. According to a second distinction, Averroes affirms that not only are the heavens, as the primary moved bodies, self-moved, for reasons that we have seen, but they are self-movers in a stricter sense of the term than are animals. Terrestrial animals are self-moved by a mover that is not the prime mover, and so their self-motion, and their existence, can cease, since it depends on a higher cause. By contrast, the mover within the celestial self-mover is the prime mover, so that its self-motion is everlasting. This is the distinction, then, between what is essentially versus accidentally « self-moved » 62. Hence, Averroes will speak of the movers of the heavens as souls (although not, following Aristotle’s example, in the Physics) 63. He presents arguments independent of the Physics for celestial animation 64. Of course, the term « soul » is applied to celestial and terrestrial things only in equivocal senses of the term 65.

62 In libros Physicorum..., VIII, 6 (259b30-31), t.c. 52, f. 393DE ; Questions in Physics VII, p. 238, 11-14, 18 (¶ 34-35): a[x«\^ ¹Î\¤¬b µ¯. Cf. De substantia orbis : Hebrew, chap. 2, 37-41 ; 6, 105-112 ; Epitome in Physicorum libros, VIII, 4, p. 138, 1-5 ; p. 139, 8-9.

63 See especially De substantia orbis: Hebrew, chap. 2, 9. 64 The Tahafot at-Tahafot presents two general modes of argument : (1) by process of

elimination, given that non-cognitive, non-volitional pure nature does not cause motion for its own sake, circular motion, or contrary motions (Tahafot at-Tahafot 14-15, p. 471-3, 480-81, 484 ; cf. also disc. 3, p. 184-85, 188-91, 215-16 ; Averroes, Compendio de Metafísica, Texto árabe con traducción y notas de C. Quirós Rodríguez, Madrid, Imprenta de Estanislao Maestre, 1919, bk 4, ¶ 7, 1-8) ; cf. De substantia orbis : Hebrew, chap. 6, 74-78 ; (2) from the fact that animate is superior to inanimate, and that superior bodies, as the causes of inferior animate things, must themselves be animate (Tahafot at-Tahafot 3, 4, 9, p. 189-90, 271, 408 ; Commentum magnum super libro De celo et mundo, II, 12, t.c. 61, p. 391, 30-37 ; De substantia orbis: Hebrew, chap. 6, 78 ; Tafsīr mā ba‘d aì-ìabī‘at, Λ, 5 (1070b36-1071a3), t.c. 25, p. 1534, 3-10 ; Compendio de Metafísica 4, ¶ 7, 8-12 ; ¶ 65, 4-11 ; Averroes, Kitāb al-Sama’ wa-al-‘Ālam [= Epitomē De Coelo], in Rasā’il Ibn Rušd, Haydarābād (Deccan), Dā’irat al-ma‛ārif al-‛uîmāniyya, 1365-66/1946-47, vol. II, p. 41, 10-14. As H. A. Wolfson observes, Averroes expressly draws the latter mode of argument from Alexander ; see H. A. Wolfson, « The Problem of the Souls of the Spheres », p. 29, 31, 43 ; Alexander of Aphrodisias, On the Cosmos, ed. C. Genequand, Leiden-Boston, E. J. Brill, 2001, ¶ 7-8.

65 Averroes, Tahafot at-Tahafot 14, p. 473, 2-5 ; cf. Alexander, On the Cosmos ¶ 9, as noted in Averroes’ Tahafut al-Tahafut (The Incoherence of the Incoherence), trans. from the Arabic with introduction and notes by S. van den Bergh, London, Luzac, 1954, vol. II, p. 159. See Avicenna, Liber de anima, seu sextus de naturalibus I-II-III, édition critique de la traduction latine médiévale

AVERROES’ PRIME MOVER ARGUMENT 27

D. The Distinction between Per accidens Moved « by Another » versus « by Reason of Another »

Still, one must ask whether Averroes’ account of celestial ensoulment allows for a consistent interpretation of the passage on which it is founded: Physics VIII, 6, 259b28-31. Grant that celestial souls are « separate », not subsistent in the celestial body, and therefore not per accidens self-moved with their body. Yet, the same passage states that there is, in fact, per accidens motion in the heavens, motion caused, not by themselves, but by another. In what sense, then, can such celestial souls be « accidentally moved by another » if they cannot be accidentally moved by themselves ? Averroes’ answer constitutes the third distinction in the Long Commentary on the Physics 66. « Per accidens moved by another » is not used here in its proper sense, he clarifies, as is the case with terrestrial self-movers, whose soul is « per accidens moved by another because its subject enters into its very definition » as the form of matter (393B). By contrast, the celestial body does not enter into the definition of the celestial soul, as we have seen 67. Thus, although lower celestial bodies are per accidens moved by the outer celestial spheres, this « being moved per accidens by another » does not alter the disposition of the celestial soul. As others later put it, the celestial soul is per accidens moved only « by reason of another », that is, by relation to its sphere, which is accidentally carried along by an outer sphere 68.

For Averroes, then, Physics VII and VIII, 1-6 conclude to a prime mover that is an absolutely immobile part within a self-moved whole. We can express the nature of the prime mover arrived at by this stage in a premise :

(6) There must be a first mover that is part of a self-moving whole, but which does not subsist within the part that is moved, and which is separate both in definition and being.

par S. van Riet ; introduction sur la doctrine psychologique d’Avicenne par G. Verbeke, Louvain-Leiden, Peeters-Brill, 1972, I, 1, p. 32, 89-96. « Form » is also said equivocally of the heavens and of hylomorphic composites, since in the former, the subject is not the « condition of the being » of its motion-causing form ; De separatione…, p. 110, 3-6, 28-30 ; cf. p. 108, 2-5 ; 110, 13-25 ; 112, 1-4 ; 114, 28-32 ; Epitome in Physicorum libros, VIII, 10, p. 149, 13-14.

66 In libros Physicorum..., VIII, 6, t.c. 52, f. 393A-C. 67 See above, at n. 56. 68 See, for example, John of Jandun, Super octo libros Aristotelis de Physico auditu…, op.

cit., VIII, 14, f. 120FGa.

DAVID TWETTEN 28

Stage III: The Nature of the Prime Mover Proved by the End of Physics VIII, 10

A final stage remains in the Averroean understanding of the prime mover argument in Physics VIII. Chapter 10 proves « more properly » than before, says Averroes, that the prime mover is not a body and is not per accidens movable, by proving that it is, not in, but outside matter and subsisting through itself : extra materiam and subsistens per se 69. In short, it is « not a body nor a power in a body », according to the last line of the Long Commentary 70. The question is, does Averroes understand the argument here to arrive at a mover that is a different entity beyond the one whose existence has been defended thus far, namely, the first unmoved motion-causing part of a self-moving whole ? Within the Long Commentary, there is evidence for both a negative and an affirmative answer. In fact, Averroes’ exposition of Chapter 10 raises nearly as many questions as it answers. I take up his comments in two parts, considering first the Argument from Infinite Potency; second, the location of the first mover.

A. The Argument from Infinite Potency

In brief, Aristotle’s central argument in Chapter 10 is based on the (unexpressed) premise that :

69 Averroes, In libros Physicorum (Guldentops), VIII, 10, t.c. 78, f. 423I, 16-17 ; f. 424A, 20-23, in Guldentops, « Edition of Averroes, Physica, VIII, Chs. 78-79 & 86 ». Cf. Averroes’ summary of the conclusion in De separatione…, p. 106, 5-9 ; 112, 8-9 ; 126, 31-32 ; Epitome in Physicorum libros, VIII, 10, p. 147, 10-11 ; p. 149, 8-9 ; p. 151, 15-16 ; De substantia orbis : Hebrew, chap. 3, 9, 24-25 ; 6, 28-32 ; Questions in Physics VII, p. 240, 7, 15 (¶ 42) ; q. 8, ¶ 3, 5 ; Tafsīr mā ba‘d aì-ìabī‘at, Λ, 1, t.c. 5, p. 1424, 16-1425, 1 ; Λ.7, t.c. 41, p. 1634, 9-10 ; Commentum magnum super libro De celo et mundo, I, 2, t.c. 5, p. 13, 32-35, reading materiam for naturam ; Averroes, Epistle 1 (on Intellect) ¶ 20, p. 210, and Averroes, De perfectione animae 2.160-165, ed. C. Steel, both in Averroes, La béatitude de l’âme.

70 « [N]on... corpus nec virtus in corpore », In libros Physicorum (Guldentops), VIII, 10, t.c. 86, f. 433M, 31-32. See also ibid. VIII, 10, t.c. 78, f. 424A, 19-21 ; 79, f. 425I, 21-22 and 426GH, 96-102 ; Commentum magnum super libro De celo et mundo, I, 3, t.c. 22, 140-145 ; Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1626, 11-1627, 2 ; 1627, 12 ; 1637, 3-5 (summarizing Themistius) ; Questions in Physics, VIII, ¶ 2 ; De substantia orbis : Hebrew, chap. 4, 20-21, quoted below, n. 149 ; cf. ibid. chap. 3, 1-4. Cf. also Avicenna, Al-Shifā’: Al-Ilāhiyyāt, ed. G. C. Anawati, Sa‛Õd Zāyid, Cairo, Organisation Générale des Imprimeries Gouvernementales, 1960, vol. II, 9, 4, p. 402, 1-3.

AVERROES’ PRIME MOVER ARGUMENT 29

(7) Only an infinite [active] potency 71 can cause [continuous, circular] motion for an infinite time 72.

But were such a potency in a finite magnitude, argues Aristotle, it would be divisible and finite. Therefore, there must be a first mover that is not in a finite magnitude, that is therefore indivisible, without parts or magnitude73. We might imagine that such a mover must be more « separate » in its substance than a part of a self-moving whole, or a celestial soul. Averroes’ immediate conclusion to the argument, however, suggests otherwise by reaffirming what he had taken Physics VIII, 6 to conclude regarding the nature of the prime mover :

From this it is clear, therefore, that the celestial body is not composed of matter and form, and that it is simple, and that its form does not have subsistence (امu{) through it, and that this [form] is what moves it, and that in it [the celestial body] there is absolutely no material form 74.

In a long digression in the Long Commentary, Averroes raises two problems, in which he treats the question that concerns us here : how could this conclusion be true, namely, that the heavens are finite in themselves but are moved by an infinite potency ? In particular, an infinite potency would cause a motion of infinite velocity – which would be instantaneous and therefore impossible 75. Furthermore, Aristotle himself also affirms, in apparent

71 The first stage of Aristotle’s argument in Chapter 10 is to prove that nothing finite (peperasme/non) can cause motion for an infinite time (266a12-24, 267b23-24). In the next stage, he introduces the language of potency or power, arguing that an infinite potency (du/namij) cannot exist in a finite magnitude (266a25-26, 267b22-23). For the distinction between active and passive potency, see Aristotelis Metaphysica, ed. W. Jaeger, Oxford, Clarendon Press, 1957, ∆, 12, 1019a15-20 ; ∆, 15, 1021a14-18. For Premise (7.1), see below at n. 142.

72 Such motion has been proved to exist in the preceding chapters, where Aristotle defends the view that first motion is simple, continuous (Physics VIII, 6-7, 259b32-260a26 ; 260b19-26), and circular (Chapters 8-9). For Premise (7), cf. Averroes, Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1627, 6-7 ; 1634, 8-9 ; 1637, 6-7 ; 1638, 6-8.

73 See Aristotle’s statement of his conclusion, Physics VIII, 10, 266a10-11, 267b17-19, 25-26 ; also Metaph. Λ, 7, 1073a5-7.

74 Averroes, In libros Physicorum (Guldentops), VIII, 10, t.c. 79, f. 427AB, 148-151 : « Ex hoc ergo patet corpus celeste non componi ex materia et forma et ipsum esse simplex, et quod forma ipsius non habet subsistere per ipsum, et quod ipsa est que movet ipsum, et quod in ipso non est forma materialis omnino ».

75 In libros Physicorum (Guldentops), VIII, 10, t.c. 79, f. 426HI, 104-114. See also De separatione…, p. 106, 20-33 ; p. 120, 22-28 ; De substantia orbis : Hebrew, chap. 3, 16-23 and 57-59 ; 6, 119-120 ; Commentum magnum super libro De celo et mundo, II, 6, t.c. 38.78-87 ;

DAVID TWETTEN 30

contradiction, the finitude of the heavens’ potency. First, says Averroes, this affirmation follows, unless the heavens are an exception, from a premise that is assumed here in Physics VIII, 10 :

(8) Every body has finite potency 76.

Second, Averroes adds, Aristotle expressly affirms celestial finitude :

(8.1) For Aristotle, the potency of the heavens is finite 77.

According to the De caelo, explains Averroes, each sphere carries only the number of stars appropriate to it ; any more than that would cause fatigue 78.

Epitome in Physicorum libros, VIII, 10, p. 148, 8-9 ; Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1627, 18-1628, 2 ; p. 1629, 12-13 and 16-17 ; Questions in Physics VII, p. 241, 2 ; p. 241, 23-242, 1 (¶ 43, 46), where Averroes observes that everything moved is moved by a mover with a determinate velocity and time ; also q. VIII, ¶ 5 ; 9, ¶ 9. For the rejection of change in a moment, see Aristotle, Physics VI, 3, 634a24-b7. For helpful discussions, see C. Steel, « Averroes’s Interpretation of the Final Section of the Physics », in Averroes Latinus: A New Edition…, p. xi-xiv ; H. A. Davidson, « The Principle That a Finite Body Can Contain Only Finite Power », in S. Stein, R. Loewe (eds.), Studies in Jewish Religious and Intellectual History: Presented to Alexander Altmann on the Occasion of his Seventieth Birthday, Tuscaloosa, Alabama, University of Alabama Press, 1979, p. 75-92, at 83-85 ; R. Glasner, « Gersonides on Simple and Composite Movements », Studies in the History and Philosophy of Science, 28 (1997), p. 545-84, at 551-53.

76 Averroes, In libros Physicorum (Guldentops), VIII, 10, t.c. 79, f. 426HI, 104-07 and 109. See Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7 (1073a7-8), t.c. 41, p. 1627, 8-13, where Averroes introduces Premise (8), and subsequently Premise (8.0) (cf. below, at n. 184), in discussing Aristotle’s premise : nothing finite has infinite power. For Premise (8), see also ibid. p. 1628, 11 ; p. 1629, 1-2 and 6-8 ; Questions in Physics, IX, ¶ 5, 7 ; De substantia orbis: Hebrew, chap. 6, 115, quoted below, at n. 152. Cf. Aristotle, De caelo II, 12, 293a10-11 : panto_j de\ peperasme/nou sw&matoj pro_j peperasme/non h9 du/nami/j e0stin ; the power of every finite body is finite. Averroes connects this proposition to an alleged previous affirmation in the De caelo that the active and passive power of any body is finite, and that the heaven has finite power in action and passion ; Averroes, Commentum magnum super libro De celo et mundo, II, 12, t.c. 71, p. 408, 24-26 ; p. 410, 94-97. Averroes seems to refer to De caelo I, 7, 275b22-23, where Aristotle affirms, citing his Physics, that no finite body has infinite potency [for causing motion].

77 Averroes, In libros Physicorum (Guldentops), VIII, 10, t.c. 79, f. 426L, 125-128 ; 427B, 155-156 ; 427D, 167-170 ; De substantia orbis: Hebrew, chap. 3, 52-53 ; Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1630, 11-1631, 2 ; De separatione…, p. 124, 18-24. Cf. the ascription to Aristotle in ibid. p. 128, 10-11 ; De substantia orbis: Hebrew, chap. 4, 30-33 ; 6, 121-122 ; De substantia orbis Junta, chap. 7, f. 13IK.

78 In libros Physicorum (Guldentops), VIII, 10, t.c. 79, 127-128 (f. 426L) ; De separatione…, p. 124, 18-24 ; p. 128, 16-20 ; Commentum magnum super libro De celo et mundo,

AVERROES’ PRIME MOVER ARGUMENT 31

In the course of answering this question, Averroes makes a number of claims, which it will be helpful to isolate and itemize. Together they amount to his clarification of what Premise (8.1) must mean. Does Aristotle refer to an active potency in the movers or to a passive potency in the celestial body 79 ? Averroes begins with the latter :

(8.2) The passive potency in the heavens to receive motion is finite 80.

For, such a potency, he explains, exists in the celestial body, and so it is finite and divisible just as is the body 81. Each sphere, of course, is moved with a unique velocity and direction, which it receives from its mover.

It would seem to follow that the active potency in the heavens is also finite, which would be an alternative reading of Premise (8.1) :

(8.3) The active potency of the celestial movers to cause motion is finite 82.

Averroes does not affirm this, however, in the Long Commentary. It might be taken to be entailed by his general principle : the greater the mover, the greater the velocity of its motio or motion-causing 83. Yet he infers from this principle only the finitude of the movers’ action or operation :

II, 6, t.c. 38, p. 343, 89-93 ; Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1631, 1-7 ; cf. p. 1635, 8-14 (quotation of Themistius). The Arabic version of De caelo II, 12, 293a10-11, of which Scot’s Latin is here a faithful record, contains the consequence of weariness and fatigue not found in editions of the Greek ; see Aristotle, De caelo et Meteorologica, ed. A. Badawi, Cairo, Maktabat al-NahÈa al-Miêriyah, 1961, p. 276, 2-6.

79 For Averroes’ reference to this distinction, see In libros Physicorum (Guldentops), VIII, 10, t.c. 79, f. 425I, 26-27.

80 In libros Physicorum Aristotelis (Guldentops), VIII, 10, t.c. 79, ff. 426M-427A, 136-148. Guldentops’ edition and apparatus greatly clarify Averroes’ discussion throughout. The argument seems to require finita in l. 136. For Premise (8.2), see also De separatione..., p. 122, 2-124, 8 (without mention of « potency » ; but cf. « virtutes », p. 124, 5) ; « potency finite in action and passion » in De substantia orbis: Hebrew 3.79 ; De substantia orbis Junta, chap. 7, ff. 13I-14A, D ; Commentum magnum super libro De celo et mundo, II, 12, t.c. 71, p. 410, 87-89 and 94-97 ; Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1630, 7-1631, 5 ; cf. p. 1629, 1-8.

81 In libros Physicorum (Guldentops), VIII, 10, t.c. 79, f. 426M-427A, 136-140. 82 See below, n. 134. 83 In libros Physicorum (Guldentops), VIII, 10, t.c. 79, f. 427C, 163 ; cf. Tafsīr mā ba‘d aì-

ìabī‘at, Λ, 7, t.c. 41, p. 1631, 1-7.

DAVID TWETTEN 32

(9) In the case of immaterial movers, no less than in material movers, their motion-causing (motio) must be finite 84.

For, motion-causing that is infinite is impossible, since an infinite velocity would mean instantaneous change, as we have seen 85. In fact, continues Averroes, Premise (9) is the reason that one sphere is moved more quickly than another, despite the fact that each of their movers is not in matter 86. For this reason, Aristotle affirmed – in this sense – that the potency of the heavens is finite [Premise (8.1)], and that if there were more or larger stars, a given sphere’s motion would slow down or come to a stop 87.

The claims of Averroes reported thus far, although they clarify Premise (8.1), only partially address the question with which we began. Aristotle’s arguments in Physics VIII, 10 presuppose that the mover of the heaven must have infinite potency. How is this possible if the passive potency and the active motion-causing in the heavens must be finite ? Averroes seems to offer two different explanations, which I report in Premises (10) and (11) 88. At a glance, they appear to entail a contradiction, though it is not difficult to suggest a resolution. First, Averroes introduces a distinction that is frequently found also in other works :

84 In libros Physicorum (Guldentops), VIII, 10, t.c. 79, f. 427C, 164-165. For the question of the finitude of the movers’ operari or operatio, cf. De separatione..., p. 120, 30-31 ; p. 122, 2, 7-9, 16-25, 34 ; p. 124, 1-3 ; p. 128, 10-16 ; and n. 97 below. The De substantia orbis affirms that the action (and passion: ההפעלות והפעל) of the celestial « bodies » (which term therefore includes their movers) is finite ; De substantia orbis: Hebrew, chap. 3, 75-76 ; also Commentum magnum super libro De celo et mundo, II, 12, t.c. 71, p. 410, 87-89.

85 In libros Physicorum (Guldentops), VIII, 10, t.c. 79, f. 427C, 159-162 ; see above, n. 75. 86 In libros Physicorum (Guldentops), VIII, 10, t.c. 79, f. 427CD, 165-167. Nearly the

identical affirmation is made at De substantia orbis: Hebrew, chap. 3, 76-77. 87 In libros Physicorum (Guldentops), VIII, 10, t.c. 79, f. 427D, 167-170. See also De

substantia orbis: Hebrew, chap. 4, 30-37 ; 6, 121-123 ; De substantia orbis Junta, chap. 7, f. 14E ; cf. Questions in Physics VII, p. 241, 21-24 (¶ 46).

88 Indications are that this is a text-commentary that Averroes improved with subsequent corrections, as was his practice. See especially R. Glasner, « Review of Averroes, Middle Commentary on Aristotle’s De anima. A Critical Edition of the Arabic Text with English Translation, Notes, and Introduction, by Alfred Ivry », Aestimatio, 1 (2004), p. 57–61. Final clarification of Averroes’ argumentation will depend on the critical edition of the Long Commentary on the Physics, which is being prepared by H. Schmieja.

AVERROES’ PRIME MOVER ARGUMENT 33

(10) There are two kinds of infinite motive potency (ة ^��آ�u{) 89 : infinite in velocity (�b��) versus infinite in duration (ء]ey) of action 90.

Elsewhere one reads alternative versions of the same distinction :

(10.1) There are two senses of « infinite potency » : infinite in strength or intensity .91 (ز^[ن) versus infinite in time (`�ة)

What is the point of Premise (10) ? As Averroes goes on to say, a potency infinite in velocity is impossible, unless motion in an instant is possible. He implies that a potency that is infinite in duration of action is possible. Instead of saying so, when he takes up the question directly, he offers the following solution :

(11) « Finite » and « infinite » are said only of bodies, whereas what is not in a body is not called « finite » or « infinite » 92.

He even gives a reason for Premise (11) :

89 I draw the Arabic from Commentary on Aristotle’s Book on the Heaven and the Universe: Sharh { Kitāb ArisìūìālÕs al-Samā’ wa-l-‘ālam (facsimile edition of ms 11821, National Library, Tunis [= Long De cael. Comm. Facsimile]), ed. G. Endress, Frankfurt a. M., Institute for the History of Arabic-Islamic Science, 1994, II, 6, t.c. 39, p. 223, 14, 22. I supply the rest of the Arabic in Premises (10) and (10.1) from Questions in Physics VII, p. 241, 23-242, 1 ; p. 242, 16-243, 1 (¶ 46, 48), where the senses of « infinite » are distinguished in the case of the heavenly bodies.

90 In libros Physicorum (Guldentops), VIII, 10, t.c. 79, f. 427BC, 156-162. See Commentum magnum super libro De celo et mundo, II, 12, t.c. 63, p. 395, 46-396, 54 ; Questions in Physics, IX, ¶ 9. Cf. De separatione…, p. 120, 31-32 : infinite secundum operari versus infinite secundum durationem sui esse.

91 De substantia orbis : Hebrew, chap. 3, 70-71, where the distinction is introduced and usually characterized as one between a potency that is infinite in time, but finite in itself (בנפשו), that is, in velocity (במהירות) and intensity (חוזק ; vigore), versus a potency that is infinite in itself (ibid. chap. 3, 61-63) ; correspondingly, a potency, action, or passion that is finite in itself is contrasted with a potency, action, or passion that is « finite in time » (ibid. chap. 3, 79-90). See also De separatione..., p. 122, 8-18 : potencies « infinite in time » versus « in strength » (fortitudine) ; Commentum magnum super libro De celo et mundo, II, 12, t.c. 71, p. 410, 75-79, 94-101 : potencies finite « in quality » versus in « quantity of time » ; cf. ibid., II, 6, t.c. 38, p. 342, 71-343, 95 ; t.c. 39, p. 344, 31-345, 34 : infinitas intensionis (ةvƒ ; Long De caelo Comm. Facsimile, p. 223, 13). For the background of Averroes’ distinction, especially in Avicenna, see P. Lettinck, Aristotle’s Physics and Its Reception, p. 591-93, 662-63.

92 In libros Physicorum (Guldentops), VIII, 10, t.c. 79, f. 427EF, 178-184 ; De separatione..., p. 120, 29-122, 2.

DAVID TWETTEN 34

(11.1) In movers that are not in bodies, there is no greater or lesser potency, nor any proportion between their active or motive potencies 93.

(11.2) For, greater and less belong only to quantity, and proportion is only between one magnitude and another, and belongs only to things in a magnitude 94.

Premises (10) and (11) are united in the goal of « saving » the everlasting motion of the heavens. If we take Premise (11) literally, however, it affirms that « infinite potency » cannot be said to belong to the celestial mover, even « infinite in duration of action », contrary to Premise (10). Nor can « finite motion-causing » be said to belong, contrary to Premise (9). Perhaps, then, Averroes simply means that « finite » and « infinite », properly speaking, cannot be said of separate potencies 95. Accordingly, « infinite potency », properly speaking, refers to « infinite in velocity », and in this sense it cannot be said to belong to incorporeal movers. Similarly, « finite potency », properly speaking, belongs only to movers in bodies, and in this sense it cannot belong to immaterial, unquantified things, which therefore admit of no proportional comparisons among themselves. Can Averroes mean, then, that improperly speaking, the celestial mover can be said to have a potency that is infinite in the duration of its action, but finite in its velocity and motion-causing 96 ?

The De separatione primi principii gives an account that may also explain what Averroes has in mind in the Long Commentary. According to Averroes there, no separate form is either finite or « infinite in strength » in itself, but each is « equal » without strength, though « infinite in time » ; thus, each subject

93 In libros Physicorum (Guldentops), VIII, 10, t.c. 79, f. 427F, 184-191 ; De separatione..., p. 122, 7-15 and 23-25 ; see also below, n. 97. Elsewhere, however, Averroes orders and distinguishes the celestial movers according to more and less in understanding and desire ; Commentum magnum super libro De celo et mundo, II, 10, t.c. 58, p. 385, 90-96.

94 In libros Physicorum (Guldentops), VIII, 10, t.c. 79, f. 427FG, 186-187, 191-93. See De separatione..., p. 120, 32-122, 2 ; p. 128, 14-15 ; De substantia orbis: Hebrew, chap. 6, 31-33.

95 This point is made explicit at De separatione..., p. 120, 29-32, where Averroes, far from seeing a contradiction, uses Premise (10) precisely to explain Premise (11). Averroes puts an analogous reconciliation in the mouth of the objector: even if a infinite corporeal power would cause motion in an instant, it does not follow that an infinite incorporeal power would have this impossible consequence [since it would be infinite in an entirely different sense] ; In libros Physicorum (Guldentops), VIII, 10, t.c. 79, f. 426I, 111-114.

96 The De substantia orbis speaks of this sense of « infinite » as « finite in itself » ; see above, n. 91. For the affirmation of an agent that is infinite secundum suam naturam, see De substantia orbis Junta, chap. 7, f. 14A, quoted below, at n. 175 ; cf. 14D.

AVERROES’ PRIME MOVER ARGUMENT 35

in the heavens receives an equal passio 97. Although the quantity of each diverse passion received in the subject is proportional in velocity to the motion-causing form 98, the proportionality is entirely the result of the quantifiable, divisible subject, not of the form in itself 99. The celestial subject is not a « condition of the action » of its form, so that no strength or weakness is found in the operation of that form as such (unlike in the case of terrestrial movers) 100. The consequent proportion between mover and moved, a requirement of their contrariety, is constant, admitting no « more or less » 101. For the De separatione, then, finitude in the celestial motive potencies or in the proportionality to their effects is not due to the movers themselves. Nevertheless, Averroes apparently contradicts this doctrine in the later Long Commentary on the De caelo, affirming that the cause of the different proportions between the potencies of the movers and what they move is the diversity of the forms themselves 102. Similarly, in the Long Commentary on the Metaphysics, it becomes important to emphasize the falsehood of the materialist Sabaeans’ view that the finitude of the celestial mover’s activity occurs only on account of the effect on it of the body moved 103.

In any case, Averroes’ set of claims clearly allows us to identify better than before the nature of the prime mover proved in Physics VIII. We may summarize it as follows :

(12) There must be a first mover that has infinite potency in the duration of its action, though its motion-causing is finite in velocity (even if neither « finite » nor « infinite » are properly said of it).

97 De separatione..., p. 122, 7-10. 98 De separatione..., p. 122, 9-12 ; Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1630, 5-1631, 7. 99 De separatione..., p. 122, 2-124, 8 ; p. 128, 10-16. Cf. De substantia orbis : Hebrew,

chap. 3, 52-53: according to Aristotle’s De caelo (in Averroes’ eyes), the potency of celestial bodies are finite in action because their bodies are finite in magnitude ; also, ibid. chap. 2, 61, quoted at n. 146 ; 3, 87-90 ; 6, 96 and 115-116, quoted at n. 152 ; Commentum magnum super libro De celo et mundo, II, 12, t.c. 71, p. 410, 94-98 ; cf. ibid., 71-91 ; and Questions in Physics VII, p. 241, 23-24 (¶ 46). For a different doctrine in the Long Commentaries on the De caelo and Metaphysics, however, see below, at n. 102-103. Nevertheless, for a way to resolve the apparently contradictory solutions, see below, at n. 234.

100 De separatione..., p. 122, 17-18. 101 De separatione..., p. 120, 9-13 ; p. 128, 20-28 ; see Commentum magnum super libro De celo

et mundo, II, 12, t.c. 63, p. 395, 18-44 ; Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1630, 5-1631, 7. 102 Commentum magnum super libro De celo et mundo, II, 6, t.c. 38, p. 343, 98-102 ; cf.

t.c. 39, p. 344, 31-345, 34 ; I, 2, t.c. 5, p. 14, 67-68. But see above, n. 95, 99. 103 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1634, 11-1635, 2 ; cf. 1633, 11-1634, 4.

DAVID TWETTEN 36

Premise (12), thus, gathers together Premises (9) and (10) [and (11)] : Premises (9) and (10) are not contradictory, and they can be taken to describe attributes of one and the same moving cause. Does anything in Averroes’ claims prove that the first mover to which he refers in Chapter 10 is a different entity from the first mover of Chapter 6, namely, from the first part of a first self-moving heavens ? It is « more properly proved than before » that the prime mover is « not a body nor a potency in a body », that it is « outside matter »104; otherwise, not only would it be per accidens moved, but it would also have potency that is finite in every sense. Still, « separateness in being » and non-material constitution were already evident in a non-hylomorphic, non-inherent form, as was proved to exist in Chapter 6.

B. The Location of the First Mover

On the other hand, one other passage in the Long Commentary on Physics VIII, 10 does suggest that Averroes intends « first mover » to refer to the first or highest reality in his cosmos (and therefore perhaps not to a celestial soul). One of the last questions Aristotle addresses in the Physics is the « location » of the prime mover : is it « at the center » (§n m°sƒ) or « at the circumference » (§n kÊklƒ) 105 ? He answers that the mover is nearest where the motion is fastest, and the mover is there (§ke›). Averroes explains that « there » refers to where the mover’s effects are, where its causing motion is equally divided among all of the parts moved by it 106. Furthermore, the « nearness » must be understood to refer to a proximity in being rather than in location; so that the principle of motion is nearest the outermost sphere 107. For, strictly speaking, the celestial mover, insofar as it is not in matter, has no place 108. Nothing in Aristotle’s text, thus, prevents Averroes from taking it to support the view that the prime mover is a non-inherent sphere-soul, that acts at the circumference of the sphere.

But there is more. Averroes offers support for his reading by appealing to what religious norms say : « Hence, all the laws concur in this, that God dwells

104 See above, nn. 69-70. 105 Aristotle, Physics VIII, 10, 267b6-9. 106 Averroes, In libros Physicorum..., VIII, 10, t.c. 84, f. 432E. 107 In libros Physicorum..., VIII, 10, t.c. 84, f. 432GH. Averroes’ comment depends

ultimately on reading tou~ o#lou at 267b8-9. 108 In libros Physicorum..., VIII, 10, t.c. 84, f. 432E.

AVERROES’ PRIME MOVER ARGUMENT 37

in the heavens » 109. In other words, as religion teaches, God is « there », not literally as in a place, but through what he effects. This appears to be the first time that Averroes refers to « God » in the context of the prime mover argument of the Physics. It at least indicates that Averroes has no difficulty in identifying God with the prime mover concluded in Physics VIII. Furthermore, backreferences in the Long Commentary on the De caelo indicate that Averroes regards himself as having spoken in his own name in the Long Commentary on the Physics : « [B]y now the manner in which God is said to be in the heaven has been spoken of at the end of Physics VIII, and will be spoken of more in the Divine Science » 110. Similarly, he comments on Aristotle’s reference to « what is there » outside the heaven, which is not in place :

Should we understand from this [that] the first cause [« is there »], Aristotle ascribes it to « what contains » [that is, to the first orb] because its causing motion [motio] appears primarily there, and for this reason he said at the end of Physics 8, « the mover is therefore there », namely, in the circumference [in convexo] of the sphere ; and it is evident that what is not in matter is not in place 111.

On the other hand, when Averroes subsequently refers to the Physics’ determination of the « place where the mover’s power appears », he identifies this place with the « right » (hand) of the proximate celestial mover, namely, of a soul not inherent in its sphere – a place that is therefore neither intrinsic nor extrinsic to the heaven112. Could Averroes mean that God or the first cause is the proximate mover of the first heaven, which he likens to an imaginary man

109 In libros Physicorum..., VIII, 10, t.c. 84, f. 432F. 110 Commentum magnum super libro De celo et mundo, I, 3, t.c. 22, p. 45, 108-110, where

Averroes also comments on common belief. 111 Commentum magnum super libro De celo et mundo, I, 9 (279a16-19), t.c. 100, p. 188,

36-40, where Averroes finds the same interpretation in Themistius’ account of Alexander. Cf. ibid., 57-68. For « prima causa » and « causa causarum », see ibid., 94-104 ; see also De substantia orbis Junta, chap. 7, f. 14EF.

112 Commentum magnum super libro De celo et mundo, II, 2, t.c. 15, 41-65 ; for celestial animation by a soul that is united to its matter without « cohering to it through the mediation of dimensions », and that is « not divided by the division of its body », see ibid. II, 1, t.c. 3, p. 274, 36-275, 43 ; on ensoulment see also t.c. 4, p. 275, 12-276, 24 ; II, 2, t.c. 13, p. 287, 25-288, 32. For « not divided by the division of the body », cf. Epitome in Physicorum libros, VIII, 10, p. 147, 13 ; De substantia orbis: Hebrew, chap. 1, 159-161 and 181-82 ; De substantia orbis Junta, chap. 7, f. 13HI ; Epistle 1, ¶ 19-20, p. 210, De perfectione animae 2, 151-166, De animae beatitudine 1, 191-200, ed. C. Steel, in Averroes, La béatitude de l’âme.

DAVID TWETTEN 38

circumscribed by the sphere, whose right hand is in the east and who faces down over the earth 113 ?

Without answering this question, we may express as follows one final premise from the Physics :

(13) There must be a first mover that is « where » its effect is, namely, at the circumference of the sphere, just as God is said to be « in the heavens ».

Stage IV: The Distinction between Celestial Soul and Intelligence

As we have seen up to this point, the prime mover argument in the Physics, on Averroes’ reading, concludes to a first unmoved mover that is part of a self-mover, and no characteristics affirmed of the first mover – not even infinite in potency – appear to preclude it from being the proximate mover of the heavens, which must be a celestial soul. Also, Averroes suggests that this first mover is the absolutely first being or « first cause » inasmuch as he makes reference to « God ». Still, these facts create difficulty for our understanding of the prime mover argument, difficulty sufficient to suggest that it must be completed by a final stage not found in the Physics. Why ?

A. The Problem : How Does the Prime Mover Argument Arrive at the First Cause ?

A series of points constitute the problem, which it may be helpful first to list as steps, then to present the evidence for them where it is needed. (1) As we have seen, no argument in Physics VII-VIII appears to require there to be a first mover that is more « separate » than a celestial soul, part of a self-moving whole. (2) Yet, it would seem that for Averroes the first cause or God cannot be a celestial soul. (3) In fact, in a number of texts Averroes apparently affirms two celestial movers for each sphere, a soul and an Intelligence. The clearest and most important affirmation occurs in the Long Commentary on the

113 Commentum magnum super libro De celo et mundo, II, 2 (285b2-3), t.c. 13, p. 288, 39-289, 68 ; t.c. 14, p. 291, 65-292, 77 ; t.c. 15, p. 292, 16-293, 28, according to which lower spheres that move from west to east are imagined to have a man inscribed who stands on the same pole and whose back is to the earth.

AVERROES’ PRIME MOVER ARGUMENT 39

Metaphysics. (4) But no new argument for the existence of an Intelligence or a first cause beyond a celestial soul can be found in Metaphysics. For, contrary to Avicenna, the existence of separate substances can only be proved in natural philosophy. Metaphysics borrows this proof from natural philosophy and discusses the nature and properties of separate substances, such as how they move as formal and final causes. (5) In fact, since according to Averroes it is idle to affirm entities that are outside sense perception or that do not account for experienced effects, separate substances can be affirmed only as causes of motion. How and where, then, does the Commentator see the prime mover argument to arrive at what can only be a first cause, if not in Physics or Metaphysics ?

(1) No argument in Physics VII-VIII appears to require there to be a first mover that is more « separate » than a celestial soul, part of a self-moving whole. This is a conclusion from the first three stages above, given that there must be as first mover an everlasting self-mover. Its unmoved part must not inhere within its body, but must be the source of its everlasting movement.

(2) Yet, it would seem that the first cause or God is not a celestial soul. I can quote no line in Averroes maintaining that it is impossible or false that God is a sphere-soul, and some thinkers did ascribe this thesis to him 114. In the demonstrative works Averroes does not appear to consider the thesis, let alone reject it, as he rejects, for example, polytheism 115, or the claim that the first mover is material and is not something separate 116. Observe, however, that if Averroes maintains the view commonly ascribed to Aristotle that the first mover is exclusively a final cause 117, then God, the first cause, cannot be an efficiently moving celestial soul.

114 See, for example, the attribution by Albertus Magnus, De causis et processu universitatis a prima causa 1.4.7, p. 53, 68-70, in Albertus Magnus, Opera omnia, ed. Institutum Alberti Magni Coloniense, Münster i. West., 1951-, vol. 17, 2. For Elijah, see above, n. 6. The impossibility of this thesis does follow, however, from Averroes’ claims in the Long Commentary on the Metaphysics. See below, Stage IV.B.2-3.

115 Commentum magnum super libro De celo et mundo, II, 1, t.c. 6, p. 279, 52-54. 116 This is the motivation for writing the De separatione... (see p. 96-100). See also

Commentum magnum super libro De celo et mundo, I, 3, t.c. 22, p. 46, 129-142 ; Tafsīr mā ba‘d aì-ìabī‘at, Λ.7, t.c. 41, p. 1633, 11-1635, 4, discussed below at n. 183 ; Questions in Physics, VIII, ¶ 7 ; and the text below, at n. 119.

117 This is suggested, for example, by the statement that according to the Metaphysics, an intelligible form that moves the heavens is not moved except by desire ; Commentum magnum

DAVID TWETTEN 40

(3) In a number of texts Averroes apparently affirms two celestial movers for each sphere, a soul and an Intelligence 118. This follows, for example, from one passage in which he presents the arguments of Physics VIII, 10 as countering the common claim that, given an animated heaven, there is no need for a separate, extrinsic mover :

^a وa£¤g أزل_، أ¡c ال»w[وي ال�ªم هu ال¥ي الw¨��ك ه¥ا أ^� ^a£¤g a لc ]wأ¡ }uم  a و}� 119.^¯[رق ³[رج ^a ^��ك إل± ی�¨[ج ل£® أ¡c ¡¯®، ذو أ¡c أ^�­

But the clearest and most important affirmation occurs in the Long Commentary on the Metaphysics :

[I]t has already been shown that this [everlasting] motion must be put together (�¯fµ^) through two movers: a mover that is finite with respect to causing motion (¶ال¨��ی) – and this is the soul that is in it [the heavenly body]; and a mover that is infinite with respect to causing motion – and this is the power (ةueال) that is not in matter. According as [the heavenly body] is moved by the finite power that is in it, it is moved in time.... Through the difference in the proportion – in the heavenly bodies – namely, between their bodies and their souls (ال·»¤�)there is a difference in [their] quickness and slowness. And, through their agreement in the fact that they are not moved except by a power that is in what is not material, there exists in them the permanence and continuity of their motion 120.

super libro De celo et mundo, II, 12, t.c. 61, p. 391, 45-392, 52. I take up this issue below, at n. 210 and 224.

118 In addition to the texts quoted in the following two notes, see Epistle 1, ¶ 3-4, p. 200, and De perfectione animae ¶ 2, 31-36 ; Tafsīr mā ba‘d aì-ìabī‘at, Λ, 5, t.c. 25, p. 1534, 12-1535, 12 (quotation of Alexander). The distinction is entailed at Tahafot at-Tahafot 14, p. 481, 3-6 ; De substantia orbis: Hebrew, chap. 4, 15-23 and 6, 94-97, 113-118, quoted below, at nn. 149, 152 ; and it is suggested at ibid. 2, 59-68, quoted below, at n. 146 ; Commentum magnum super libro De celo et mundo, II, 1, t.c. 4, p. 275, 19-276, 23 (not supported by Long De caelo Comm. Facsimile, p. 145, 23-24) ; cf. De separatione..., p. 112, 26-114, 10 ; p. 126, 31-128, 10, discussed below, in n. 228.

119 « Because it was shown that this [first thing] moved, namely, the celestial body, is eternal and had a soul, people thought that it did not need a separate, extrinsic mover » : Questions in Physics VII, p. 241, 12-13 (¶ 45).

120 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7 (1073a9-11), t.c. 41, p. 1630, 2-5 and 8-11 ; cf. 1631, 14-15. Averroes had previously affirmed that the heavens are ensouled in the context of discussing the absolutely first mover, which moves only as an object of desire ; ibid. Λ, 7 (1272a26-27), t.c. 36, p. 1593, 12-14.

AVERROES’ PRIME MOVER ARGUMENT 41

(4) But no new argument for the existence of an Intelligence or a first cause beyond a celestial soul can be found in Metaphysics. Averroes argues, contrary to Avicenna, that the existence of separate substance can only be proved in natural philosophy 121, through motion 122. No science can prove its own subject matter 123. Hence, Metaphysics cannot prove the existence of God 124, to the extent that its subject, being insofar as it is being or separate being, is identified with the first separate being, God 125. Instead, it borrows the proof of this being from natural philosophy 126, and it asks whether immaterial being is one or many 127, and investigates immaterial being as the principle of substance as substance 128. Metaphysics, not Natural Philosophy, discusses the nature of these principles and their properties 129, such as how they are movers 130, especially as formal and final causes 131.

(5) In fact, since it is idle to affirm entities that are outside sense perception or that do not account for experienced effects, separate substances can be affirmed only as causes of motion 132. How and where, then, does Averroes see

121 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 1 (1069a30-33), t.c. 5, p. 1422, 5-9 ; In libros Physicorum..., I, 9 (192a35-b2), t.c. 83, f. 47F-I (where he adds, echoing Aristotle: without such proof, there would only be natural science and mathematics) ; II, 2 (194b14-15), t.c. 26, f. 59BC ; VIII, 1 (251a8-9), t.c. 3, f. 340EF ; De separatione..., p. 96, 10-13. See also H. A. Wolfson, « Averroes’ Lost Treatise on the Prime Mover », in H. A. Wolfson, Studies in the History of Philosophy, vol. I, p. 402-429, at 409-16 ; H. A. Davidson, Proofs for Eternity, Creation and the Existence of God in Medieval Islamic and Jewish Philosophy, Oxford, Oxford University Press, 1987, p. 311-18.

122 Averroes, Tafsīr mā ba‘d aì-ìabī‘at, Λ, 1, t.c. 5, p. 1423, 8-14 ; De separatione..., p. 96, 13-17.

123 In libros Physicorum..., I, 9, t.c. 83, f. 47G. 124 Averroes, Treatise on the Prime Mover, p. 409, in H. A. Wolfson, « Averroes’ Lost

Treatise on the Prime Mover ». 125 Averroes, In libros Physicorum Aristotelis..., I, 9, t. 83, f. 47G. 126 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 1, t.c. 5, p. 1424, 11-1425, 1 ; In libros Physicorum...,

VIII, 1, t.c. 3, f. 340EF ; Compendio de Metafísica I, ¶ 9, 1-2 ; De separatione..., p. 96, 22-24 ; Treatise on the Prime Mover, p. 409.

127 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 1, t.c. 5, p. 1424, 13-15. 128 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 1, t.c. 5, p. 1424, 11-13 ; p. 1425, 10-1426, 4. 129 In libros Physicorum..., II, 2, t.c. 26, f. 59BC. 130 Compendio de Metafísica I, ¶ 9, 1. 131 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 1, t.c. 5, p. 1425, 4-5 and 12-13 ; t.c. 6, p. 1433, 9-14 ;

p. 1433, 18-1434, 4 ; p. 1435, 6-1436, 2 ; S. Harvey, « Averroes’ Prooemium to His Long Commentary on Physics », p. 65, 19-21.

132 Averroes, Tafsīr mā ba‘d aì-ìabī‘at, Λ, 8, t.c. 44, p. 1648, 4-8.

DAVID TWETTEN 42

the prime mover argument to arrive at what can only be a first cause and not a celestial soul, if not in Physics or Metaphysics ? Or, is there another way to explain how the Physics’ argument surpasses as celestial soul ?

B. The Argument for the Necessity of Two Distinct Celestial Movers

As we have seen in A3 above, Averroes affirms two movers of the sphere, one that accounts for finite velocity, another that accounts for its infinite motion. The grounds for this distinction would apply to each of the spheres, so that it appears that Averroes affirms a duality of movers for each. Further, he refers to this conclusion as already having been shown. But where ?

The question can also be asked of Aristotle : where does he argue that there must be a separate final cause that moves the first efficient cause as an end? In other words, where does he show that what immediately moves the heavens as an efficient cause cannot be the absolutely first cause, which moves as an object of love ? One plausible approach, suggested in Aristotle and the commentary tradition, is to argue that a celestial soul cannot be the first mover, but must be itself moved insofar as it causes motion through desire. One can find passages in Averroes that could form the basis for such an argument, and that are even suggestive of its existence 133. Still, one would have to explain why there could not be a separate efficient cause that moves without desire or that moves only for its own sake. Averroes, of course, could find an explanation in Premise (3) : extrinsic efficient causes are moved movers.

1. The Discussion of the Treatises Entitled De substantia orbis

Fortunately, however, we do not have to construct an Averroean argument, since we do find argumentation establishing the duality of movers in the treatises gathered under the title De substantia orbis. The structure of the argument is presented in « Chapter » 3, beginning with a premise that was not stated, as we noted, in the Long Commentary on the Physics :

133 See, for example, De substantia orbis: Hebrew, chap. 4, 15-17, quoted below, at n. 149 ; Commentum magnum super libro De celo et mundo, II, 12, t.c. 61, p. 391, 38-392, 52 ; cf. Tahafot at-Tahafot 14, p. 481, 3-6.

AVERROES’ PRIME MOVER ARGUMENT 43

(8.3) The active potency of the celestial movers to cause motion is finite 134.

For the sake of clarity, we may add that it is finite in strength and velocity, as follows, based on Premises (10) and (10.1) :

(8.3.1) There must be celestial movers whose active potency to cause motion is in itself finite, that is, in strength and velocity 135.

Averroes offers several grounds for Premise (8.3). First, he takes it to follow from his reading of De caelo II, 12, expressed in Premise (8.1) : for Aristotle, the potency of the heavens is finite 136. Second, Premise (8.3) follows from an analysis of the cause of the motions of the various celestial spheres. The assumption is that each motion has its own mover 137. But this mover must be related or proportioned to a particular sphere that has a determinate size and number of stars 138, time-period of rotation 139, velocity 140, and direction peculiar to itself (so that each outer sphere within a

134 The De substantia orbis affirms Premise (8.3) regarding « virtutes active finite moventes » (כחות פועלות) : De substantia orbis Alonso, chap. 3, p. 230, 11-12 ; De substantia orbis: Hebrew, chap. 3, 59-60 ; cf. 52-53. See also ibid. 3, 79 ; 6, 71-72 (cf. l. 55-70) and 122 ; De substantia orbis Junta, chap. 7, f. 13I-14A, D ; Commentum magnum super libro De celo et mundo, II, 6, t.c. 38, p. 342, 67-343, 102 ; t.c. 39, p. 345, 45-50 ; II, 12, t.c. 71, p. 410, 87-89 and 94-97 ; Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1630, 2-1631, 7 ; p. 1632, 18-19. Cf. De substantia orbis: Hebrew, chap. 4, 17-19, quoted at n. 149 ; De separatione..., p. 124, 18-24 ; p. 128, 10-28. Premise (8.3) also follows from the universal Premise (8), understood of active powers, as in Premise (8.0) ; see below, n. 184.

135 Averroes states the universal premise from which this follows ; see below, n. 184. Cf. Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1630, 2-1631, 7, partially quoted at n. 120. For « finite in itself » in the De substantia orbis, see above, n. 91. Notice that the same argument would go through – as long as it is completed by Premise (7.1) – even if we understood this premise after the manner of the Long Commentary on the Physics, which may be expressed through Premise (8.3.2) : There must be celestial movers whose active potency to cause motion is neither finite nor infinite. See above, at n. 92-97.

136 De substantia orbis: Hebrew, chap. 3, 52-53 ; Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1631, 1-2. See above, n. 77.

137 For the assumption defended, see below, at n. 220. 138 Commentum magnum super libro De celo et mundo, II, 6, t.c. 38, p. 342, 70-74 ; p. 343,

89-93. 139 De substantia orbis: Hebrew, chap. 3, 63-65, 76 ; Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7,

t.c. 41, p. 1630, 4-5, quoted above, at n. 120. 140 De substantia orbis: Hebrew, chap. 3, 54-60, 76 ; Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7,

t.c. 41, p. 1630, 8-10 ; p. 1631, 1-7 ; Commentum magnum super libro De celo et mundo, II, 6, t.c. 38, p. 342, 68-343, 92.

DAVID TWETTEN 44

nest of planetary spheres is ordered to the motion of the star on the innermost sphere). Since a cause infinite in strength would cause motion in an instant, each moving cause must have its own finite strength and velocity 141.

On the other hand, recall that at the core of Aristotle’s Argument from Infinite Potency in Physics VIII, 10 is Premise (7) :

(7) Only an [active] infinite potency can cause [continuous, circular] motion for an infinite time.

Hence, in the midst of affirming, in both the De substantia orbis 3 and in Long Commentary on Metaphysics Λ, a finite active potency, according to Premise (8.3.1), Averroes affirms also an infinite active potency :

(7.1) There must be celestial movers whose active potency to cause motion is infinite in duration or time 142.

Within these immediate contexts, Averroes appears simply to assume that an active potency that is finite in strength and velocity cannot account for a motion that is infinite in duration. This assumption cries out for justification 143. We might almost think that the whole point of the analysis in the Long Commentary on Physics VIII, 10 is to allow for a motion-causing or moving power that is both infinite in duration and finite in strength. Nevertheless, two passages in the De substantia orbis suggest the following reason :

(14) Everything that is finite in its activity must be finite in the duration of its activity 144, unless infinite duration is imparted to it by another.

141 De substantia orbis: Hebrew, chap. 3, 57-60 ; Commentum magnum super libro De celo et mundo, II, 6, t.c. 38, p. 343, 86-89 ; t.c. 39, p. 344, 31-345, 37.

142 De substantia orbis : Hebrew, chap. 3, 66-67, 71-72 ; Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1630, 10-11 (quoted above, at n. 120) ; p. 1638, 2-8 (following Themistius, p. 1635, 4-1637, 9).

143 Aristotle’s Argument from Infinite Potency is vulnerable at this point. What prevents a power that is finite in strength from causing a motion that is infinite in duration ? Such a power need not be lacking magnitude, parts, and division, need not be a separate and immaterial mover, but may be a body or a power in a body. This is precisely the objection and the conclusion of Crescas ; see W. Harvey, Physics and Metaphysics in Hasdai Crescas, Amsterdam, J. C. Gieben, 1998, p. 51-52, 69-72. Nevertheless, we shall see that Averroes has an elaborate answer to this question.

144 De substantia orbis: Hebrew, chap. 2, 63-64, italicized in the quotation at n. 146 ; see also ibid., chap. 6, 115-116, italicized in the quotation at n. 152.

AVERROES’ PRIME MOVER ARGUMENT 45

Accordingly, De substantia orbis 3 speaks of the celestial body as receiving an action that is finite in itself, but infinite in time 145. And, what imparts infinity of duration is not the same as the source of its finite action of circular motion. For evidence, consider a passage from « Chapter » 2, read against the background above :

[T]his celestial body needs not only a power moving it in place but also a power imparting to it (largiente, יקנהו), in itself and in its substance, eternal permanence. For, even if it [the body] is simple, having no potency in itself for corruption, nevertheless it is necessarily of finite action, since it is finite, having dimensions determined by the surface containing it. And, it is necessary in the case of every such thing, though the intellect might have supposed it to be something existing per se and lacking another imparting to it permanence and eternity, that there belong to it a finitude of its permanence just as a finitude of its action. And for this reason, it is necessary that there be an intellect as a power imparting to it eternal permanence just as it imparts to it eternal motion. And, not only this, but it is necessary that there be a power that imparts to it a motion proper to its action, which is eternity among the other motions, namely, circular locomotion, and a shape proper to /152/ this motion, namely, spherical, and a measure proper to each of these bodies, and a fitness in order and quantity among each other 146.

In this passage, the Intelligence is said to be the power that imparts the everlasting character of celestial motion. The distinction between Intelligence as the source of infinity and the appetitive power as finite is expressed in a passage from « Chapter » 4 :

And when [Aristotle] considered these powers [in the celestial body], it was declared that there belongs to it, from among the powers of the soul, only the appetitive power itself. And when he considered the celestial appetitive powers (virtutibus ; התשוקייות he saw that they are moved toward an appetible that ,(כחות is more noble than they. And when he considered the celestial appetitive powers, he found them to be among the finite 147 powers. And when he considered the

145 De substantia orbis: Hebrew, chap. 3, 87 ; cf. 77-78. 146 De substantia orbis Alonso, chap. 2, p. 151, 1-152, 3 (De substantia orbis: Hebrew,

chap. 2, 59-68). Since an English translation of the Hebrew already exists except for « Chapter » 7, I translate the Latin, which is an independent witness of the original Arabic (except for « Chapters » 6-7).

147 Alonso reads « infinite » instead of finite ; see De substantia orbis: Hebrew, chap. 4, 17-18 ; De substantia orbis Junta, chap. 4, f. 10F.

DAVID TWETTEN 46

continuation of eternal motion, it was declared that the cause of the continuation in their motion 148 is not that by which they are moved, but what imparts to them continuation is that appetible. And, because continuation only comes from an unmoved mover, it follows that that mover is neither a body nor a power in a body, and that it is an abstract intelligence. For, it was declared in the book On the Soul that everything that is of such a kind is an abstract intelligence. And that celestial body /248/ understands this intelligence 149.

Here for the first time we see, then, Averroes indicating the distinction between a proximate celestial power (referred to here once by « celestial body ») that causes motion through desire for the sake of a separate Intelligence as its appetible good. Again, the former is held to be a finite power (in strength), the latter is the source of infinite motion (in time) 150. And, only the latter is identified with the absolutely unmoved mover of Physics VIII, 10, whereas desire is a moved mover. Averroes echoes these claims also in « Chapter » 6 :

[I]f there is a celestial body, /K/ it is impossible but that there be in it an appetitive power by which it is moved toward a mover that is an end; and that it be, with appetitive power, intelligent (intelligens, כילמש ), and that this appetitive power, with its being in (esse in, היוחו בגשם) a finite body, be finite151, even if it is simple, as we have said.... And, since the motion [of the celestial body] is continuous, /13A/ and [the body] is in itself finite, moved through a form that is in it, which is an appetitive soul; and [since] the celestial body was animated, and everything animated is moved toward what is loved through a desire existing in it; and [since] every body was of finite power; thus it is manifest that if the power of desire were in this body, as such it would be of only finite motion-causing (motio, הנועה). And, it is manifest that it would acquire continuation of motion through the mover toward which [its] motion has an end. And hence it was declared... that [this] is an

148 Again, I follow the reading of the Junta and Hebrew editions. 149 De substantia orbis Alonso, chap. 4, p. 247, 1-248, 1 (De substantia orbis: Hebrew,

chap. 4, 15-23). For the doctrine of the De anima, see below, n. 209. 150 A. Hyman, in notes to this passage, acknowledges that the appetitive mover causes a

motion of finite intensity, whereas Intelligence explains infinite duration ; yet, although this passage and Long Commentary on Metaphysics Λ, 7, p. 1630 suggest that the two movers are separately existing principles, other passages (affirming agent-end identity) show that they are different aspects of the same celestial form (A. Hyman, Averroes’ De substantia orbis, p. 113-115, n. 18-19).

151 The majority of the Hebrew mss, with A. Hyman, read « infinite ».

AVERROES’ PRIME MOVER ARGUMENT 47

intellect abstracted from matter, and that the heavens are moved /B/ only according as they understand it 152.

This quotation, especially when considered together with the previous one, even suggests a reason for Premise (14) :

(14.1) The active, appetitive potency that causes celestial motion, since it is in the celestial body, must be, as such, finite in both its activity and in the duration of its activity 153.

2. The Discussion of the Long Commentary on Metaphysics Λ

The structure of the argument for the distinction between celestial soul and Intelligence, we have seen, is fleshed out most fully in De substantia orbis 3, through the equivalent of Premises (7.1) and (8.3.1). At the same time, the ground needed for the argument, expressed in Premise (14), is at best only indicated in two passages from « Chapters » 2 and 6 of the De substantia orbis. By contrast, the Long Commentary on the Metaphysics, although it only alludes to the argument’s structure, fills out in some detail further grounds that Averroes has for distinguishing two celestial causes. The grounds may be summarized in the following premise :

(14.2) The moving power in the celestial bodies has the possibility of causing motion or of not causing motion.

Averroes introduces this premise in the midst of a lengthy digression on the last paragraph of Lambda 7 (Text 41), where Aristotle presents a résumé of the Argument from Infinite Potency in Physics VIII, 10. In the course of rejecting

152 Averroes, De substantia orbis Junta, chap. 6, f. 12I-K, M and 13A-B (De substantia orbis: Hebrew, chap. 6, 94-97 and 113-118, which reads, in the last line, « are moved toward it only... »).

153 There will be many parallels in Averroes for the claim that a power in a body must be finite, since this is central to the Argument from Infinite Potency of Physics VIII, 10, as is reiterated by Aristotle at the end of Metaphysics Λ, 7 ; see Premises (8) and (8.0), at n. 76, 184. As for the doctrine that the source of infinity cannot be, as such, in a body, see, for example, Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1630, 2-5, quoted above, at n. 120. Compare especially Themistius’ claim that powers in bodies that are infinite (in duration) are not infinite insofar as they are themselves corporeal ; ibid. p. 1635, 6-7, at n. 155 below ; or Averroes’ claim that only movers that are in no way in bodies or material can account for why infinite powers in bodies do not exercise their capacity not to move ; ibid. p. 1637, 14-1638, 6, discussed below, at n. 159-161 ; p. 1633, 5-9, at n. 166. I return to this theme below, at n. 170, 186, 200, and 231.

DAVID TWETTEN 48

Philoponus’ view that a heaven that is finitely powerful must therefore lack infinite duration, and so must have been created, Averroes quotes a long passage from Themistius’ Commentary on the Metaphysics as a help in distinguishing kinds of potency 154. Themistius speaks of an infinite « power that is in » the celestial body, which is neither « natural in it » nor there from the fact that it is a body 155. He distinguishes the « first cause » from this power which depends on it, and/or from « the soul in [the celestial bodies] that is from that power that is not corporeal » (1635, 7-8). He affirms that the source of infinite, everlasting motion (which he identifies, at least ultimately, with the first cause) lacks potency, is eternally in act, and is not in a body 156. There is, Themistius admits, something in potency in the celestial bodies, since they change place; and therefore they have finite powers (1635, 11-14). How, then, can what is in potency for a finite motion admit of perpetual change ? Any act, he answers, that follows upon a prior potency does not have the possibility (aºwی) of perduring forever, but must have an end 157. But an act that is separate per se has the possibility of perduing infinitely in time everlasting (1636, 6-7). Therefore, the moving power (آ���wة الueال) that is in the celestial bodies is infinite, since their use of this power is in no way potential (ةueل]y), even though they also possess a finite motion, and a potency with regard to place 158.

Accordingly, Averroes takes the opportunity to clarify in what way the heavens have a potency or power that does not jeopardize the eternity of their motion. The moving powers (آ���wة الueال) that are in bodies, he explains, are of two kinds : either powers in corruptible bodies (namely, the sublunar powers)

154 See also Themistius, Paraphrase de la Métaphysique d’Aristote (livre Lambda), traduit de l’hébreu et de l’arabe, introduction, notes et indices par R. Brague, Paris, Vrin, 1999, p. 96-97 ; A. Martin, Averroès. Grand commentaire de la Métaphysique d’Aristote (TafsÕr mā Ba‘d aì-ìabÕ‘at). Livre lam-lambda, traduit de l’arabe et annoté, Paris, Les Belles Lettres, 1984, p. 254-55. R. Sorabji explains that Averroes mistakenly ascribes Philoponus’ view to Alexander ; R. Sorabji, Matter, Space, and Motion : Theories in Antiquity and Their Sequel, Ithaca, N.Y., Cornell University Press, 1988, p. 264-69 ; see also S. Harvey, « The Impact of Philoponus’ Commentary on the Physics on Averroes’ Three Commentaries on the Physics », in P. Adamson, H. Baltussen, M.W.F. Stone (eds.), Philosophy, Science and Exegesis in Greek, Arabic and Latin Commentaries, London, Institute of Classical Studies, 2004, p. 89-105.

155 Averroes, Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1635, 6-7 ; cf. p. 1636, 10-11. 156 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1635, 8-9 ; p. 1636, 3-5. 157 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1636, 1-2 and 7-10. 158 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1636, 10-13. For a similar point ascribed to

Themistius, see De separatione..., p. 112, 17-20.

AVERROES’ PRIME MOVER ARGUMENT 49

that do not have the possibility (aºwل£® ی) of causing motion perpetually because they change (]ه�£»g) in themselves and their subject changes ; « or, moving powers in eternal bodies that have the possibility (]¼ی¯ aºwی) of causing motion perpetually and of not causing motion perpetually » 159. Notice that these latter (celestial) powers, unlike the former, do have the possibility of causing everlasting motion, since, he implies, they neither change in themselves nor through their subject. But they also have the possibility of not causing everlasting motion. If there is everlasting motion, Averroes continues, then that toward which they are moved, that is, the first mover, is not changed in any way whatsoever and is not at all a body 160. Finally, he adds, paraphrasing a remark of Themistius that referred to the celestial soul : « [I]f there is an eternal [thing] moved, it must be moved by a power in it from a mover that is not changed in any way whatsoever and that is [therefore]... immaterial » 161.

Averroes’ affirmation of a power to cause everlasting or infinite motion that has the possibility of not causing motion is a surprising development in Book Lambda 162. For, according to the central conclusion of Chapter 6, only a cause that is in no way in potency, in its substance or operation, can account for everlasting motion (1071b12-22). At first face, Aristotle’s conclusion would seem to exclude from the heavens a mover that has the possibility of not causing motion. Nevertheless, Averroes’ affirmation is not a solitary slip of the pen within the Long Commentary on the Metaphysics. It is confirmed by a number of parallel and supporting claims, which I reduce to three in number and discuss serially.

Let’s begin with a similar claim that Averroes introduces there regarding the celestial body :

(14.2.1) The only possibility (ن]º^إ) in the heavens, given that they are indestructible in substance, is for them to come to rest [that is, by not being moved] 163.

159 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1637, 11-15. 160 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1638, 2-4. 161 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1638, 4-6 ; cf. p. 1635, 6-8. 162 For recognition of this doctrine, and of the consequent need for an external, separate

cause other than the intrinsic, immanent celestial soul so as to account for everlasting motion, see B. Kogan, Averroes and the Metaphysics…, p. 186-87 ; 200-01 ; cf. above, at n. 4.

163 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1631, 12-13.

DAVID TWETTEN 50

Averroes directly adds a qualification: this possibility of coming to rest, of course, « does not exist » – in fact, « its impossibility has already been shown » – precisely because there exists a mover in which, again, there is no potency, whether per se or per accidens, and so it is not in matter 164.

Averroes, immediately after introducing Premise (14.2), alludes to a supporting claim for it other than what arises from the discussion of Themistius : this (distinction about the different kinds of potencies) is very particularly evident, he says, in the fact that the celestial body is necessarily ensouled 165. Averroes leaves for us to fill in his reference. But he had previously drawn out an implication of ensoulment for the question of celestial potency :

Also, if (1) the celestial body has already been shown to be moved by itself, and (2) everything which is moved by itself has the possibility (aºw^) of coming to rest by itself – and I mean by « [everything] which is moved by itself » everything moved by will and desire (قu`إرادة و) – yet (3) it has already been shown to be impossible that there be rest in the celestial body; then (4) the perpetuity of its motion is on account of a mover in which there is no potency (ةu{) for change in any way whatsoever, whether per se or per accidens. And so, the mover for the celestial body is necessarily an immaterial power 166.

What causes motion through desire, as such, has the possibility of stopping itself. And so, since motion is everlasting, what causes motion through desire, even if it has no potency for change, must be caused by an absolutely immaterial moving power. Let us formulate this as a second ground for Premise (14.2) :

(14.2.2) The celestial body, just insofar as it is moved by itself and so causes motion through desire, has the possibility of bringing itself to rest.

164 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1631, 13-15 ; cf. p. 1629, 14-15 ; p. 1633, 7-8, quoted at n. 166. For the fact that the non-eternity of motion is impossible, see Physics VIII, 1 ; see also Questions in Physics, IX, ¶ 6. For the conclusion to a mover that lacks potency and matter, see Aristotle, Metaph. Λ, 6, 1071b18-21. The notion of the possible (and the impossible) here, however, is Avicennian, as will appear in the next section. See also J. Puig Montada, « Potencia y posibilidad en Averroes », in Actas del I Congreso Nacional de Filosofía Medieval, ed. J. Lomba Fuentes, Saragossa, Ibercaja, 1992, p. 431-37.

165 Averroes, Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1638, 9-10. 166 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1633, 5-9 ; cf. also p. 1637, 11-1638, 6, at

n. 159-161.

AVERROES’ PRIME MOVER ARGUMENT 51

Averroes, it is worth adding, does not use the fact that any self-mover has the possibility of acting otherwise as evidence that the heavens are not ensouled. Instead, he appeals to the ensoulment of the heavens and to the consequent possibility for alternative action to show the necessity of a moving power in which there is no possibility and which is in no way in the celestial body.

A third ground for Premise (14.2) provides the ground also for the previous two grounds, and, in fact, gives important insight into Averroes’ grounds for Premise (14) : Everything that is finite in its activity must be finite in the duration of its activity, unless infinite duration is imparted to it by another. Hence, I list it as :

(14.3) If the [moving] power in the celestial body is finite [as according to Premise (8.3)], there is the possibility ( ^º[نا ) that the heavens come to rest 167.

This premise, in its immediate context, appears to be used merely as part of a hypothetical argument. It occurs close to the outset of Averroes’ response to Philoponus in Comment 41, and it contains his first reference to « possibility » in this response. Averroes immediately adds, as elsewhere, that it has already been shown that the celestial body does not come to rest 168. Nevertheless, Averroes subsequently also maintains the premise’s conditional in an absolute sense, as Premise (8.3) ; and he subsequently affirms, as we have seen in Premises (14.2.1) and (14.2.2), the possibility of the heavens’ coming to rest.

There is other evidence for Premise (14.3), and it helps us understand what it affirms. Averroes’ next reference to possibility appears to be a premise that grounds Premise (14.3) :

(14.3.0) In the celestial body there is no possibility (ن]º^إ) in its substance, and there is no possibility in its subject except to receive motion and to cause motion alone 169.

This premise indicates the two possibilities to which Premise (14.3) is open: to receive and to cause motion. These could be further cashed out in two premises :

167 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1629, 13. 168 See above, n. 164. 169 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1630, 7-8. Contrast this premise with

Averroes’ denial that the heavens have a potency to be moved or not moved, since otherwise their action and passion must be finite in time ; Commentum magnum super libro De celo et mundo, II, 12, t.c. 71, p. 410, 83-91, considered also below, at n. 222.

DAVID TWETTEN 52

(14.3.1) The celestial body has the possibility to receive motion or not receive it, and so to be brought to a rest.

Averroes does not express this, but it is the equivalent of Premise (14.2.1), assuming that the latter states something different from Premise (14.2.2). Averroes does affirm the second premise, however :

(14.3.2) The celestial body has the possibility to cause motion or not cause it, and so to bring itself to a rest.

Or, rather, Averroes maintains a universal premise that entails this :

(14.4) In every body, the action of its power, as finite, has the possibility (aºw^) of ending 170.

This premise, of course, entails, in effect, Premises (14.2), (14.2.2), and (14.3.2). But what is the significance of Premise (14.3) and the numerous statements in Comment 41 regarding the possibilities of the heavens ? Recall that the entire grounds for Averroes’ argument for two celestial causes rested on an under-justified Premise (14) of the De substantia orbis : Everything that is finite in its activity must be finite in the duration of its activity, unless infinite duration is imparted to it by another. Premise (14.3) makes a link between this Premise (14), which it will entail, and Premise (8.3) : The active potency of the celestial movers to cause motion is finite. Consequently, according to Premise (14.3), the heavens must have the possibility of ceasing to be moved. For this reason, as well as because they are moved through desire, the Long Commentary on the Metaphysics holds that they must have a first mover that is other than the celestial soul and that is in no way a power in a body. Only thus will everlasting motion be not merely possible but necessary.

Thus, as Averroes reads Metaphysics Λ, the arrival in Chapter 6 at a mover that lacks all potency and matter is also the arrival at a separate substance that moves the celestial soul as an object of desire. We may express this as a distinct premise :

(15) In order to account for everlasting motion, there must be a celestial moving power that is, unlike the celestial soul, in no way in potency and in no way in the body, but that is entirely immaterial 171.

170 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1633, 18-19, quoted below, at n. 186.

AVERROES’ PRIME MOVER ARGUMENT 53

Nevertheless, as we saw in Section A4, Averroes believes that this arrival is not new to the science of metaphysics, but already belongs to the science of nature. It was implicit in Physics VIII, 10 and was made explicit in the physicist’s subsequent examination of celestial causality.

3. The Avicennian Character of the Averroean Cosmos

To this point in our examination of Averroes’ dualism on celestial causality we have seen a remarkable amount of unanimity between the Long Commentary on the Metaphysics and the treatises entitled De substantia orbis, written perhaps some fifteen to twenty years previously 172. One may object, however, that this dualism sounds too much like Avicenna’s cosmos and the Arab emanation scheme, which Averroes clearly rejected sometime after his original composition of the Epitomē Metaphysics 173.

On the other hand, I suggest, Avicenna provides the background for the development of Averroes’ own thought, a background that remains essential in order to understand the Commentator. Averroes would have assumed this background in his readers’ minds, and it goes unacknowledged. Yet, it helps explain why Averroes appears to leave his thought somewhat incomplete or unsystematic at what appears to be a critical moment : Stage IV.

The doctrine on the necessary being as cause of all possible beings provides a case in point. Everyone knows that Averroes rejects Avicenna’s doctrine. Still, amidst the very treatises in which he rejects it, as in the Long Commentary on the Metaphysics and in the treatises De substantia orbis, he also adapts it to explicate his own position. In fact, his adaptation provides the key to his middle position between the dialectic of Philoponus and a complete dismissal of the Avicennian discourse. Averroes’ adaptation affirms :

171 See also above, n. 153. 172 « Chapter » 6 is dated 1178 ; De substantia orbis : Hebrew, chap. 6, 150. In evaluating

any work of Averroes with a comparatively early dating, of course, one must keep in mind his habit of revising his writings.

173 For Ch. Genequand, « Metaphysics », p. 794, for example, Averroes rejects Avicenna’s plurality of final causes just as much as emanation. See also above, n. 7. For Averroes’ critique of emanationism, see especially H. A. Davidson, Proofs for Eternity, Creation and the Existence of God, p. 318-35 ; B. Kogan, « Averroës and the Theory of Emanation », Mediaeval Studies, 43 (1981), p. 384-404.

DAVID TWETTEN 54

(16) The proximate celestial movers, considered in themselves, have the possibility of causing or not causing motion, but are rendered necessarily causing motion through the causality of movers whose causality is necessary through themselves.

In other words, Averroes accepts the logic of the possible and the necessary, not in the case of the coming to exist of the substance of things, as for Avicenna, but in the case their being moved 174. In this sense, Averroes finds the Avicennian logic compatible with his Aristotelian cosmos and interchangeable with his own « logic » of the finite and the infinite. Consider first a passage from De substantia orbis 7 :

We say that among corporeal receptive and active powers, some are necessarily finite according to their own natures – which are in the potency of prime matter – and it is not possible for them to be infinite, that is, to be of the nature of the necessary, whether through their own nature or through something other than themselves.... /A/ And, there are certain [others] that are finite according to their nature, but that have been rendered infinite, and that have been transferred from the nature of the possible into the nature of the necessary. For, there is an agent that is infinite and necessary according to its own nature. And those are potencies that are not in bodies 175.

As a subsequent passage states, Averroes is speaking of the celestial souls, whose active power is in itself only finite and possible, but is made infinite and necessary through another, namely, through the causality of the separate Intelligence :

[T]he souls of the celestial bodies are nothing but powers comprehending spiritual forms denuded from matter. And when [our] intellect has examined these powers and denuded them from the spiritual forms, it finds them to be of the nature of the possible. But when it has examined them according to the fact that it is impossible

174 For an « Aristotelian » version of the dialectic of the « possible » and the « necessary », cf. Averroes, Tahafot at-Tahafot 8, p. 393, 6-396, 1. For recognition of the Avicennian character of the « possible in itself, necessary through another » applied by Averroes to motion, see C. Steel, « Averroes’s Interpretation of the Final Section of the Physics », p. xiii-xiv ; Ch. Genequand, Ibn Rushd’s Metaphysics, p. 45-46. H. A. Davidson admits that Averroes’ text contains this Avicennian theme, especially as applied to motion, but he takes it to contradict main lines of Averroes’ own doctrine and criticism of Avicenna ; H. A. Davidson, Proofs for Eternity, Creation and the Existence of God, p. 325-31 ; 335. See also H. A. Wolfson, « Averroes’ Lost Treatise on the Prime Mover », p. 417-21.

175 Averroes, De substantia orbis Junta, chap. 7, f. 13M-14A.

AVERROES’ PRIME MOVER ARGUMENT 55

that they be denuded from spiritual forms, it will find them /H/ to be of the nature of the « necessary with respect to another than themselves » 176.

This passage adds a clarification : our intellect can understand the celestial souls without considering the higher forms that they contemplate and which render them necessary through another. The character of « possible in themselves » that is predicated of celestial souls, then, results from the operation of our intellect 177. And so, given the ways in which our intellect considers things, explains Averroes, Avicenna was correct about the two senses of the necessary : the necessary through itself versus through another (14F). In fact, his distinction, rightly understood, is precisely what is needed to answer the Philoponan dialectic according to which the possible must come to be in time and must be able to be destroyed (14KL). Philoponus overlooks that there are two kinds of finite powers, and that for one of them, what is possible « receives » necessity from another. As Averroes puts it, « [T]he necessary is not removed [just] because it is possible that the eternal be necessary, as Aristotle said in Physics VIII » (14L).

Similarly, Long Commentary on Metaphysics Λ, immediately after explaining in Comment 41 that the coming to rest of the heavens, though possible in itself, is in fact impossible given its cause, takes up the Avicennian « possible in itself, necessary through another » 178. Averroes expressly states that this formula applies, not to the case of a substance’s possible existence, contrary to Avicenna, but only to the case of the heaven’s being moved179. For, motion can be possible in itself and necessary through another, since being belongs to it from another, namely, from the mover; whereas substance, unlike motion, has its own permanence 180. Averroes concludes :

Every potency causing motion that is in a body is necessarily moved per accidens, and everything moved per accidens that is a mover per se is « possible » (aºw^) with respect to coming to rest from itself, [and is] moved from without it. If there

176 De substantia orbis Junta, chap. 7, f. 14GH. 177 In a similar way Averroes attributes to an act of the mind the distinction between

essence and existence in what is necessary in itself and in what is necessary through another ; Tahafot at-Tahafot 3, p. 196, 14-199, 10.

178 See above, at n. 164. 179 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1632, 1-3 ; cf. p. 1633, 2-4 ; cf. Tahafot at-

Tahafot 8, p. 394, 11-14. 180 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1632, 7-12 ; cf. p. 1630, 6-8 ; p. 1631, 8-12 ;

p. 1632, 19-1633, 4.

DAVID TWETTEN 56

is a potency in a body in which there is no possibility ( £aº^ ) of ceasing to cause motion at any moment whatsoever, it [the potency] is necessarily moved by a mover in which there is no potency at all, whether per se or per accidens. And this is the condition of the celestial body 181.

This is a difficult text to interpret independent of its background and context. Either Averroes is rejecting the doctrine that he had established elsewhere that the celestial soul is not per accidens moved with its body, or, as I argue, he is contrasting terrestrial souls, which are per accidens moved by others, with the celestial soul (in the last two lines). The celestial soul has no possibility to cease causing motion, as we have just seen in De substantia orbis 7, precisely insofar as it is rendered necessary through another, namely, through the separate Intelligence that is necessary through itself, and that is in no way in potency or in a body. Nevertheless, this absence of possibility does not belong to the proximate celestial moving power or soul in and of itself. For, Comment 41 now goes on to maintain what we have already summarized as Premise (14.2.2) : The celestial body, just insofar as it is moved by itself and so causes motion through desire, has the possibility of bringing itself to rest 182. Therefore, Comment 41 repeats, the perpetuity of its motion is caused by a mover that lacks all potency and that is necessarily an immaterial power.

As if we needed more evidence that « possible in itself, necessary through another » applies to Averroes’ proximate celestial mover, he proceeds at length to draw a corollary regarding the « Sabaeans » and those generally who reject this view. Up to this point, Averroes’ target in Comment 41 has been Philoponus’ and Avicenna’s false dialectic. Now, as in the De separatione he opposes the « physicalists » (and astrologists or star-worshipers ?) who hold that the celestial motion is absolutely necessary without any « other, more noble » cause than the celestial body itself as such, or that it is necessary that the moving power in the celestial body be eternal with respect to causing motion 183. According to Averroes, these thinkers go to the other extreme in rejecting Philoponus’ logic. They reject any finite powers (or possibility) in

181 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1632, 12-17. Compare the language in the surrounding passages, quoted above, at n. 159, 163-164, and 166. Again, Averroes’ saying that the celestial mover is moved does not commit him to saying that it is was first in potency, then in actuality, and so that it was changed or drawn from potency into act. Cf. above, at n. 157-158.

182 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1633, 5-9, quoted above, at n. 166. 183 See Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1633, 11-1635, 4, especially p. 1633, 17-

1634, 3 ; p. 1635, 2-3.

AVERROES’ PRIME MOVER ARGUMENT 57

the celestial body, otherwise the heavens must be composites of matter and form, and therefore generable and corruptible (1634, 11-1635, 3). In contrast, Averroes, again, defends finite powers in bodies, which are possible in themselves and only necessary through another. Merely from the fact that the celestial body is eternal in substance, it does not necessarily follow, he insists, that there is eternal locomotion (1633, 13-14) – but only from the fact, we may add, that they are caused by a substance separate from the heavens that is necessary in itself.

In retrospect, Comment 41 of the Long Commentary on the Metaphysics is a remarkable ten-page commentary on a version of a premise that we have seen before :

(8.0) Every power in a body is finite 184.

Philoponus affirms this premise and derives from it that the heavens are generable and corruptible. The « Sabaeans » avoid this consequence by denying the premise altogether, affirming that the heaven and/or its motion-causing power is infinitely powerful in itself. Averroes agrees that their moving power is infinite, and he introduces Themistius in evidence. But were their power infinite in itself, there would be no need for a separate cause, contrary to (the Science on the Heavens and) Metaphysics. The first cause would be the celestial body or its soul – a claim that Averroes deems false, as we now see. For him, the celestial soul has the possibility of being infinite, which Philoponus, « Alexander », and Avicenna preclude insofar as they make the soul the hylomorphic form of celestial matter. Themistius suggests a response by affirming a moving power that is not of the nature of its body ; he leaves unresolved, however, how it can be an infinite power of the heavens, which have a finite potency to be moved in place. In fact, he even suggests that only through the act of what is separate per se can celestial motion have the possibility of lasting forever. Averroes resolves this problem with Premise (8.0) and with the help of Avicenna. The heavens have an active power that is

184 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1629, 16 ; p. 1632, 18 ; p. 1634, 7-8 (every power in matter is finite) ; cf. De separatione..., p. 104, 16-17 ; p. 122, 15-16. This is a rewording of Premise (8), for which, and its sources, see above, n. 76. For the proposition that every body is finite in strength and/or velocity with respect to causing motion, see Questions in Physics VII, p. 241, 21-242, 2 ; p. 242, 15-243, 2 (¶ 46, 48). By contrast, in ibid., q. IX, ¶ 7, the proposition that every power in a body is finite (with respect to duration) in causing motion is used to show that celestial mover is not in matter.

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finite in strength, causing a body of a determinate size to be moved with a determinate velocity in a determinate direction. This power belongs to the celestial « soul » which is the proximate unmoved mover of the celestial body. At the same time, the celestial soul, insofar as it is not a form actualizing matter, has the possibility of being infinitely powerful with respect to duration, unlike terrestrial souls, and it is in fact necessarily infinitely powerful because of the separate Intelligence. As Themistius explained, this causation involves no prior and posterior in time, no going from potency to act. The celestial movers were never actually of finite duration of power; their possibility not to cause motion never « existed » and in fact has been shown to be impossible in light of their cause. Yet, « possibility » belongs to them considered in themselves, abstracted from their cause, as is explained in De substantia orbis 7.

Now we may see the force of Averroes’ striking conclusion: « This is the meaning of Aristotle’s statement 185 that every power in a body is finite : that is, its action has the possibility (aºw^) of ending » 186. Averroes here, in effect, identifies the deepest ground for Premise (14) : Everything that is finite in its activity must be finite in the duration of its activity, unless infinite duration is imparted to it by another. This premise now follows from Premise (8.3), which affirms the finitude of the celestial movers’ active potency to cause motion (since a cause infinite in strength would cause instantaneous motion). In Averroes’ eyes, Aristotle, by applying Premise (8.0) to the heavens, can arrive at Premise (14.3) : If the [moving] power in the celestial body is finite, there is the possibility that the heavens come to rest. For, Premise (8.0), that every power in a body is finite, means that a body’s action has the possibility of ending. Because every power in the celestial body must be finite, in other words, its moving power must have the possibility of not causing motion. Again, for Averroes, insofar as this power is neither material nor the form of matter, it can nevertheless be rendered incapable of not causing motion, through the influence of a higher power ; it can be rendered necessary through another. Thus, far from denying that every power in a body is finite – as the « Sabaeans » do, and as even Themistius appears to do – Averroes identifies this premise as crucial to the account of celestial causality.

185 See the previous note. 186 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1632, 18-19 ; this is the basis of Premise

(14.4) above.

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In the De substantia orbis and the Long Commentary on the Metaphysics, we may add, Averroes consciously develops his doctrine of the possible and the necessary along Avicennian lines. In his Questions in Physics IX, presumably earlier than the Long Commentary 187, Averroes objects that whoever distinguishes between caused and uncaused eternal things, especially in the case of finite powers in bodies, would be affirming an Avicennian « possible in itself, necessary through another » 188. In this treatise, however, Averroes affirms what the Long Commentary opposes: the heavens, both as to their substance (¶ 4-5) and as to their motion (¶ 6), are necessary through themselves. It is impossible that there not be motion, continues Averroes, otherwise we must affirm that it would be possible that the heavens come to a stop. And so, celestial motion requires a cause, not because it is « possible », but because every motion must have a mover 189. Consequently, the De substantia orbis and the Long Metaphysics Commentary represent a stage in Averroes’ thought posterior to Questions in Physics IX.

We have focused until now on the Avicennian theme of the « possible in itself, necessary through another », which is developed both in the De substantia orbis and in the Long Commentary on the Metaphysics. It makes sense of our findings to remember that Averroes develops his account of celestial causality against the background of Avicenna – after all, Averroes had originally accepted an emanation scheme that resembled Avicenna’s. And so, there remain points of agreement. Avicenna also affirms an Intelligence and a celestial soul for each star (although only one Intelligence

187 Again, the treatises grouped under this title were probably composed independently and not envisioned as a whole. The Arabic manuscript to Questions in Physics VII, indicates that it was completed in Seville, 1175-76, and so it was perhaps a sketch for a subsequent large work ; see Goldstein’s Introduction, Averroes, Questions in Physics…, p. xi, xiv.

188 Questions in Physics, IX, ¶ 4-5. In libros Physicorum (Guldentops), VIII, 10, t.c. 79, 129-133 associates Avicenna’s doctrine with the errors of Philoponus and Alexander.

189 Perhaps the demand of distinguishing the causality of the celestial soul from that of the Intelligence has led to Averroes’ doctrinal shift. But it would seem that the grounds for the shift is his distinction between possibility and potency. According to his alternative view, as we have seen, the « possible » is only a conceptually distinct way of understanding the « necessary through another », and entails no change from potency to act. And so, these two notions are not contradictions in terms and are not simultaneously instantiated in real existence. For an alternative interpretation, see H. A. Davidson, Proofs for Eternity, Creation and the Existence of God, p. 320 ; p. 326 ; p. 328-31 ; p. 335. On conceptual and real distinction, see Averroes, Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 39, p. 1623, 5-8.

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for each star, whereas there are over fifty ensouled spheres 190). For him, souls rather than Intelligences are necessary as proximate causes of the particular motions in particular celestial bodies 191. By contrast, the universal Intelligences, which are the ends and objects of these souls’ desire 192, account for the everlasting character of the heavens’ motion 193. Avicenna even affirms that the celestial soul is of finite power, but it is made infinite through understanding the intelligible that is of infinite power. The following quotation, given the elipses, could almost have been written by Averroes :

It is by now clear that the mover of the celestial substance causes motion from a power that is infinite. The power that belongs to its corporeal soul is finite. But inasmuch as it understands the First,... its power comes to be infinite. Infinite power does not belong to it, but to the intelligible... 194

To be sure, Averroes finds much to disagree with in Avicenna’s theory, in addition to emanation, according to the principle « from one comes only one », from a First that is not a mover (although Averroes retains the uniquely simple First) 195. In particular, the affirmation that the celestial souls are material forms inherent in the spheres as their perfections 196, and that they are consequently moved along with their spheres 197, is for Averroes irreconcilable with Aristotle’s Physics, as we have seen. Since the celestial soul cannot be a material form, it also cannot have imagination of particulars or an aestimative power 198. Averroes borrows from Avicenna a dualist theory to explain why there are two celestial movers, but he transforms it into a theory of transcendent duality.

190 Avicenna, Al-Ilāhiyyāt 9, 3, p. 401, 9-17. 191 Ibid. 9, 2, p. 383, 14-384, 13 ; p. 386, 14-387, 3 ; p. 390, 7-13 192 Ibid. 9, 3, p. 398, 1-400, 18. 193 Ibid. 9, 2, p. 384, 7-8 ; p. 389, 4-8 ; p. 393, 10-11. 194 Ibid. 9.2, p. 389, 10-13 ; cf. also p. 391, 13-392, 7. 195 See especially ibid. 9.4 ; for Averroes, see below, at n. 225. 196 Ibid. 9.2, p. 386, 14-387, 5 ; 9.4, p. 406, 12-13. 197 Ibid. 9.2, p. 387, 4-8. 198 Ibid. 9.2, p. 384, 14-385, 6 ; p. 391, 1-5. See especially Averroes, Compendio de

Metafísica 4, 6-8 ; Commentum magnum super libro De celo et mundo, II, 6, t.c. 37, p. 339, 70-340, 83.

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C. Three Objections

Objection 1. It will be useful to address directly three very legitimate objections against this way of interpreting the final stage of Averroes’ prime mover argument, objections that arise from Averroes’ text itself. First, it seems inconsistent for the final stage of the prime mover argument now to conclude to a separate intelligence that is not in a body or in matter, as according to Premise (15), as if to arrive at a mover beyond a celestial soul, which is in the body or in matter. At Stage II, we already saw Averroes, in commenting on Physics VIII, 6, conclude to a mover that is « separate in being » and that does not have matter in its constitution, although it is necessarily part of a self-moving whole. In other words, the prime mover argument in the Physics arrives at a celestial soul as prime mover which is not in the body. It seems redundant or fallacious for the argument to require another arrival at a non-bodily mover.

In response, one must take into account the suppleness of Averroes’ language, as he attempts to be faithful to Aristotle’s letter and at the same time to respond to problems of the Greek and Islamic philosophical traditions, using its idiom. In fact, Averroes explicitly affirms in the De substantia orbis, just as we have by now seen is the teaching of the Long Commentary on Metaphysics 199, that the celestial soul is « in the body » of the heavens. This affirmation is in keeping, of course, with customary language regarding any soul :

[Aristotle] found that this [heavenly body] is moved by a power that is neither heavy nor light.... And it was necessary that this power... be in a simple body (sit in ; יהיה בגרם), and that it not have a subject or contrary, and that it necessarily not be mixed with matter, but [that it] be the soul of an eternal body. Thus, it is not abstract from its body. And, as well, it is separate from it inasmuch as that body does not need it, because it is permanent per se.... Thus, this soul is in it. For, everything moved through itself is moved through a power existing in it 200.

199 See above, at n. 120 ; 159-161 ; 169 ; 181 ; 183-184 ; 186. Of course, sometimes in the same context Averroes must mean another sense of « in », as in the potency « in » the sphere to place ; Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1629, 10. Similarly, he denies that a power is « in » the heavens as inherent within a subject ; ibid. l. 14-15. Furthermore, there is a sense in which even God is « in » the heavens: as in his effects ; see above, Stage III.B.

200 De substantia orbis Alonso, chap. 4, p. 244, 2-245, 2 (De substantia orbis : Hebrew, chap. 4, 7-14) ; cf. the continuation of this passage, quoted above, at n. 149. See also ibid. chap. 1, 180-184 (cf. 169-172) ; 6, 94-97 and 113-116, quoted above, at n. 152. Avicenna also contrasts

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Thus, the celestial soul exists in the heavens in the sense that it is part of a whole by which the whole is self-moved. Averroes affirms this even while clarifying that the celestial soul is separate from the body (and so is not per accidens moved with the body). Nevertheless, he can also say, even in another « chapter » of the same work, that the soul or the proximate mover of the heavens is not in the body or matter 201. We may ascribe to Averroes a contradiction or a confusion. Yet, in the two affirmations, set forth at different places in his discussion, he makes a different philosophical point, and we can distinguish two senses of « in » in the two propositions. The soul is not « in » the heavens as in terrestrial bodies, as an inherent form of matter, although it is « in » them as a motion-causing part of the whole 202. An important recent study has underscored the integral relation of celestial mover and sphere : the mover is the very essence of the heavenly body ; and for this reason, the spheres, just as their immaterial movers, are one neither in genus nor species, but only by analogy 203. Accordingly, in another instance of flexible language, Averroes, as we have seen, frequently speaks of the heavens themselves or the celestial bodies as possessing attributes such as desire and knowledge, by which, as is often noted, he means the soul-body composite 204.

Objection 2. The strongest objection to the present reading of Stage IV of the prime mover argument lies in the passages that lead most interpreters to

celestial soul and Intelligence insofar as the former is corporeal and material, although this soul is, for him, of course, immanent in matter ; see, in addition to n. 196 above, Avicenna, Al-Ilāhiyyāt 9, 2, p. 387, 1-5.

201 Averroes, De substantia orbis Alonso, chap. 2, p. 130, 1-2 (De substantia orbis: Hebrew, chap. 2, 20 ; but see ibid. p. 78, n. 14). See also In libros Physicorum (Guldentops), VIII, 10, t.c. 79, f. 427CD, 165-167, at n. 86 above ; cf. ibid., f. 427EF, 182-184 and 190, above, at nn. 92-93. Probably the latter two passages should be understood to refer to the separate Intelligence.

202 Similarly Averroes speaks of the celestial soul as both separate and not separate ; De substantia orbis: Hebrew, chap. 4, 10-12, quoted in n. 200 ; 6, 79-83.

203 M. Di Giovanni, « Averroes on the Species of Celestial Bodies », especially p. 440 ; 457 ; 459.

204 See De substantia orbis: Hebrew, chap. 1, 169-170, 174-176 ; 6, 117-118, quoted above, at n. 152 ; Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 36, p. 1597, 10-1598, 2 ; t.c. 37, p. 1606, 13-15 ; t.c. 41, p. 1633, 5-9, quoted above, at n. 166 ; ibid. Λ, 8, t.c. 44, p. 1649, 10-11, quoted below, at n. 221 ; Commentum magnum super libro De celo et mundo, II, 12, t.c. 61, p. 391, 50-392, 52 ; Averroes, Commentarium magnum in Aristotelis De anima libros, recensuit F. Stuart Crawford, Cambridge (Mass.), The Mediaeval Academy of America, 1953, III, 4, t.c. 14, p. 428, 14-16 ; III, 11, t.c. 57, p. 530, 45-50 ; Compendio de Metafísica 4, ¶ 9 ; Tahafot at-Tahafot 3, p. 184, 10-185, 1 ; p. 192, 8-15. Cf. Avicenna, Al-Ilāhiyyāt 9, 2, p. 390, 7-13.

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conclude to the « transcendent identity » of celestial soul and Intelligence. In a number of works, Averroes appears to maintain this identity in affirming that agent and final cause in separate movers are one 205, using his well-known image of the baths 206. The most important of these affirmations, of course, is found in Comment 36 of Averroes’ Long Commentary on Metaphysics Λ. Should more weight be given to Averroes’ unambiguous assertions there than to the assertions of Comment 41 ?

A complete treatment of Averroes’ doctrine on « agent-end identity » is out of the question here, and it is beyond our scope to take up the issue of the mode of causality of the prime mover. But it is at least ironic that the two most important sets of passages setting forth « agent-end identity » are found in the two most important works establishing the distinction between celestial soul and Intelligence: the Long Commentary on Metaphysics Λ and the De substantia orbis. It is possible to discover an interpretation of « agent-end identity », I argue, that is consistent with Comment 41 and with the « transcendent duality » theory – and that even complements it.

Let us begin with Comment 36 of the Long Commentary. Aristotle affirms in Metaphysics Λ, 7 that the desirable and intelligible move in the same way as does the unmoved mover, and he goes on to clarify what he means by the desirable and intelligible. Averroes initiates his discussion by speaking of the principles that are « in » the celestial bodies 207. In these, he says, the desirable is the same as the intelligible, since the heavens have no sensation (1593.8-10). Averroes appears, then, to have in mind the celestial souls, which lack sensation ; for, no one imagines that Intelligences have sensation. Averroes continues: this doctrine makes evident another (to which he apparently refers subsequently in Comment 41) : the celestial bodies are ensouled, and among the powers of the soul, they have only intellect and the appetitive power, that is, what moves them in place 208. Averroes also speaks of the « intelligible mover » (1593, 10) and of the doctrine of Physics VIII that « the mover of these celestial

205 Averroes, De substantia orbis : Hebrew, chap. 1, 162-179 ; 2, 40-46 (cf. 2, 71-73) ; 6, 127-131 ; Tafsīr mā ba‘d aì-ìabī‘at, Λ, 10, t.c. 55, p. 1723, 11-1724, 8 ; Tahafot at-Tahafot 3, p. 232, 4-13 ; cf. Compendio de Metafísica 3, 74-75.

206 In addition to Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 36, see De separatione..., p. 112, 21-26 ; cf. 114, 34-116, 19.

207 Averroes, Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7 (1272a26-28), t.c. 36, p. 1593, 3-4. 208 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 36, p. 1593, 12-14. See ibid. t.c. 41, p. 1630, 2-4,

quoted above, at n. 120.

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bodies » is immaterial and a separate form, which is, therefore, an intellect, according to the De anima (1593, 14-1594, 2). This mover, he says, is a mover insofar as it is an agent of the motion and an end of the motion 209. These are not separated and multiplied except in us, as in the case of the form of the baths outside our soul – which is motive as end, not agent – and the desire in the soul that moves, as an agent, us toward the baths outside the soul (1594, 4-14).

By « this mover », then, does Averroes mean the Intelligence ? The immediate answer is, I believe, yes. And, he adds :

[I]n the movers of the celestial bodies, [the form] is not motive unless in both ways [that is, as agent and end], without there being multiplication. Insofar as these intelligibles are their [the heavens’] forms, they are /1595/ motive after the manner of the agent, and insofar as these are their ends, they [the heavens] are moved by them through desire (1594, 16-1595, 2).

Here by « movers of the celestial bodies », Averroes seems to mean the Intelligence, since it is identical to the intelligible form, to which he refers. But he must also mean that the intelligible form in the celestial soul is identical as agent and as end. Consequently, the form there is different from the form of the baths in our soul. Were the form of the baths not material, he argues (and so were the end attained simply by being known and loved), there would be no separation in us between agent and end (1594, 14-15). But the intelligible forms in the celestial soul are immaterial, and therefore they are at once both agent and end.

Again, then, is Averroes denying a separation between agent and end in the Intelligence, or in the celestial soul, or in both ? The answer must be : in both, if there is a distinction between the two (this is neither affirmed nor denied here), since neither of the two is material 210. Averroes’ point is not to identify

209 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 36, p. 1594, 3-4. For the argument of the De anima, see, in addition to n. 149 above, Commentarium magnum in De anima I, 1, t.c. 2, 28-30 ; III, 4, t.c. 5, 27-45 ; 665-83.

210 The reader may be surprised to discover Averroes affirming that Intelligences are both agent and final causes. For Averroes, every separate intellect, including the human agent intellect, is an end and an agent (at least in an improper sense) ; Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 38, p. 1612, 8-1613, 4 ; cf. Λ, 3, t.c. 18, p. 1502, 12-1503, 1. Thus, the first cause is a mover and an end ; ibid. Λ, 1, t.c. 6, p. 1435, 15-1436, 2 ; Λ, 8, t.c. 44, p. 1648, 4-6. And this affirmation is consistent with, or even explicative of, the claim that the prime mover moves only as an object of desire (ibid. Λ, 7, t.c. 36, p. 1592, 7-10 ; Tahafot at-Tahafot 14, p. 481, 3-6 ; cf. also Commentum

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Intelligence and celestial soul (nor to distinguish one from the other). He distinguishes the immaterial motive forms in the heavens from material forms here, such as of the baths. In the former, the form that causes motion as agent is one with the form that causes motion as end. It may be true that the form that is in the celestial soul is precisely the form of the Intelligence, which moves the heavens as both agent and end 211. This may be true, in other words, without denying that Intelligence and celestial soul are two distinct sources of motion. The text makes another important distinction that almost goes unnoticed, however : between the soul or its intellect and the form that is in it 212. On any reading of Comment 36, this distinction must be present, including according to the « transcendent identity » theory. For, lower intellects must turn out to contain a plurality of motive forms : one that causes diurnal motion, others that cause the motions specific to each planet. Averroes goes on to exploit this distinction, as we shall see in a moment. It allows him to distinguish the first, absolutely simple Intelligence from all other cosmic intellects. Only the first Intelligence is absolutely simple and lacking in multiplicity ; all other cosmic intellects know and love it (in addition to themselves), and so contain a plurality of intelligible forms 213. But first let us ask, what is the point of Averroes’ doctrine on « agent-end identity » ?

magnum super libro De celo et mundo, II, 12, t.c. 61, p. 391, 45-392, 52, and n. 117 above) ; or, as Alexander puts it, only from the side of perfection (Tafsīr mā ba‘d aì-ìabī‘at, Λ, 5, t.c. 24, p. 1529, 13-14). In fact, the affirmation follows from « agent-end identity », and therefore should hold even for the « transcendent identity » theorist ; cf. below, at n. 219. For the affirmation, cf. also, in addition to nn. 205 and 209 above, Compendio de Metafísica 3, 74-75 ; Epistle 1, ¶ 3-4, p. 200, and De perfectione animae ¶ 2, 32-36 ; Tahafot at-Tahafot 3, p. 232, 4-13. For the distinction between what is contributed as agent by an Intelligence versus by a celestial soul, see below, at the end of the response to the third objection.

211 There must be a sense in which this statement is true. Another text appears to maintain, however, that the first Intelligence is understood differently by each celestial mover, which causes diurnal motion by contemplating it ; Tafsīr mā ba‘d aì-ìabī‘at, Λ, 8, t.c. 44, p. 1649, 8-11. Cf. Ch. Genequand, Ibn Rushd’s Metaphysics, p. 42 ; Averroes, Tahafot at-Tahafot 3, p. 231, 1-9. At least we may say that the form in the celestial soul is of the Intelligence insofar as it is intelligible to the soul.

212 For this distinction, see also Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 37, p. 1604, 3-1605, 2 ; p. 1606, 13-15 ; Λ, 8, t.c. 44, p. 1649, 8-1652, 4, partially quoted below, at n. 221.

213 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 10, t.c. 51, p. 1706, 1-10. See also R. C. Taylor, « Averroes’ Philosophical Conception of Separate Intellect and God », in J. Puig Montada and A. Hasnaoui (eds.), La pensée philosophique et scientifique d'Averroès dans son temps (Proceedings of December 9-11, 1998, Cordoba Colloquium of the SIHSPAI), Paris, forthcoming.

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Averroes’ focus in Comment 36 is exclusively on explicating Aristotle’s text and on denying a multiplicity of agent and final « movers », or, better, « motive forms » 214. Nevertheless, in the earlier parallel texts, from which he borrows material for Comment 36, Averroes explains in detail what someone who rejects « agent-end identity » must hold. According to the De separatione – perhaps the oldest of the parallels – one imagines the baths in order to move oneself to something external ; once one actually arrives, one’s motion ceases 215. Were someone to affirm that the end of the heavens is similarly material as well as external to the forms « in matters » by which they are moved, argues De substantia orbis 1, these forms would be subsisting in their subjects, and so would be divisible and moved with them, so that celestial motion would be finite 216. In fact, it is characteristic of forms that subsist in subjects that they attain their perfection through other forms for the sake of which they move themselves (1, 163-164). In this sense, terrestrial animals are composed of two movers, soul and the external object of desire that moves them (2, 45-46). By contrast, in a body in which the mover does not subsist, there is no basis for the form by which they are moved and the form toward which they are moved to differ, unless it be in their disposition (1, 174-176); intellect and intelligible « in the celestial body » are one and the same (1, 178-179). Consequently, celestial motion can be eternal, never coming to an end 217. In short, then, the parallel texts disclose the fundamental point of « agent-end identity » : to preserve everlasting celestial motion. And, De substantia orbis 2 especially emphasizes that the identity belongs to the form or soul with which the celestial living whole is composed as by mover and what it moves 218.

Even if one accepts that for Comment 36, agent and final forms in the celestial soul are one, can one not still affirm that the celestial soul is an Intelligence, and that there is only one separate final cause to which each soul/Intelligence is directed ? First, this interpretation conflicts with « agent-end identity », by affirming that there is one « final cause only » that is not an agent and is not identical with the agents through which it causes 219. Second, apart from overlooking the teaching of Comment 41, one will have to reckon with

214 We find the latter language in De substantia orbis : Hebrew, chap. 1, 168-176. 215 De separatione..., p. 112, 21-24. 216 De substantia orbis : Hebrew, chap. 1, 166-167, 171-178. 217 De separatione..., p. 112, 24-26 ; De substantia orbis : Hebrew, chap. 6, 127-131. 218 De substantia orbis : Hebrew, chap. 2, 41-46. 219 See above, at nn. 8-9.

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Comment 44, which summarizes Averroes’ cosmology as well as any passage in his corpus. Averroes expands on the Aristotelian principle that one everlasting motion requires one mover, so that a planetary sphere moved with multiple motions must have multiple movers 220. We may express this as a premise :

(17) For each everlasting motion there must be one everlasting unmoved mover ; otherwise there will not be one, continuous motion.

Accordingly, Averroes writes :

[A]s for the perfection of every one of the [spheres], this is in the conceptualization of its cause, which is peculiar to it, and in the conceptualization of the first (u¿gر)cause.... It is necessary that there be for them one intelligible form apart from the form with which every one of the spheres is in accord – I mean the form peculiar to it. There is a form as end in addition to the form in accord with which each one of the remaining spheres is moved. We say that there is no form as common and universal end except the common act (ÀÁÂ) that belongs to every one of them, and this is the status that belongs to the form that moves the first heaven with respect to its daily motion 221.

Each sphere, or in other words, each (subordinate) sphere-soul, has at least two forms that it conceptualizes : the « intelligible form » of its own peculiar cause – that is, a form distinct from and the cause of the « sphere » or sphere-soul itself – and the form that is the common end (and agent) of all of the spheres. Again, here we cannot enter into the details of the mode of causality and the number of movers. Nevertheless, it is at least clear that Comment 44 entails :

(18) There must be two final causes for all but the outermost of the celestial souls: the Intelligence that is the object of desire peculiar to each of the seven planet-bearing spheres, and the First Intelligence, the common object of desire that causes the diurnal motion of all.

One may now see how Comment 36 not only need not contradict Comment 41, but also complements and furthers its doctrine. If « agent-end identity », as I argue, applies both to Intelligences and to celestial souls, we may draw some inferences for Stage IV. The celestial soul, which is of itself finite in duration and

220 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 8 (1073a22-34), t.c. 43, p. 1644, 8-1645, 7. 221 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 8, t.c. 44, p. 1649, 10-11 ; p. 1650, 8-14.

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has the possibility of not causing motion, conceptualizes the form of its peculiar Intelligence, and so its act of moving its sphere with that sphere’s peculiar motion is rendered necessary and perpetual ; or, better, the intelligible form imparted to the soul and conceptualized by it is necessarily motive of the celestial body and causes everlasting motion. Because the motive forms as agent and end are the same, there is no attainment of an external end, so that motion comes to an end once desire achieves its goal. In the celestial soul, agent-desire and intelligible end are one. « Agent-end identity », then, accounts for why the motive form in the proximate cause can move forever. It is not the case that the celestial soul receives, as if by being reduced from potency to act, some cognized external end so that its motive power changes from finite to infinite. Rather, an everlasting form that is in the soul, though distinct from it, is both an object conceptualized and loved and an agent of the peculiar everlasting motion caused by the soul. Without the celestial soul, there would be no peculiar motion. And, without the Intelligence as agent and end conceptualized and loved in the intellect of the celestial soul, everlasting motion could not be effected.

Objection 3. A final objection against this reading of Stage IV concerns its consistency with Stage I. According to Premise (15), the prime mover must be a separate Intelligence, in no way found « in » the celestial body, if everlasting motion is to be accounted for. But according to Premises (2.1) and (3), any per se series of movers must end in a first self-moved mover, since every external mover must be a moved mover. Thus, does not the argument contradict one of its founding premises in concluding to a first motion-causing Intelligence that is external to the first self-mover, an immaterial cause separate from and beyond the first celestial soul ? A parallel objection could be expressed as follows: how can one stage arrive at a celestial soul as a first unmoved mover, whereas according to a subsequent stage, it becomes crucial to see the soul as a moved mover ?

These objections give us an occasion to attend to some characteristics of the mode of causality of the prime mover or first Intelligence, even though full treatment of the issue is out of place here. Some of these characteristics were already discussed in responding to the previous objection. First, the Intelligence is not, as according to the second question above, an additional prime mover that draws something from potency into act, beyond the celestial soul. On Averroes’s reading of Aristotle’s Physics, in the order of going from potency to act, « the buck stops » at the celestial soul. Aristotle scholars traditionally express the point in saying that Aristotle’s prime mover is a final cause only ; that is, there is a first effect of the prime mover as final cause, which effect is also the first efficient

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moving cause, perhaps a celestial soul. This formulation would not do justice to Averroes’ thought, as we shall see in a moment. Yet, he agrees with and insists on the fact that the celestial soul is not moved by the Intelligence or prime mover as if the latter is a prior efficient cause, drawing it from potency to act 222. Similarly, the prime mover is not an emanator, as for Avicenna, as if all other things lack existence of themselves, but are brought into existence by the efficient causality of the per se necessary being. Another famous passage of Comment 44 expressly rejects both of these senses of agent or efficient causality 223. « There is no potency there », concludes Averroes, « and therefore there is no agent » (1652, 10). In (}uة)other words, there is no potency in the realm of separate principles, and therefore there is no agent drawing anything in them from potency to act. The Intelligence has been called a « mover » of the celestial soul as a final cause 224. But the Intelligence is not an efficient mover, properly speaking, of the celestial soul. « From one proceeds only one » is an Avicennian principle that Averroes accepts only in the case of efficient causes proper, agents of change from potency into act 225. Hence, one first Intelligence, as understood by many intellects, can be the cause of many effects, and we need not affirm a One or a Necessary Being beyond the prime mover.

Still, as we have seen in Premises (14) and (16), the heavens and their proximate efficient moving soul and power of desire must be understood to be « possible in themselves » with respect to everlasting motion ; their active and passive potency is, in itself, finite in strength and therefore also in duration. The Intelligence conceptualized by them allows them to move forever. As understood by them, it is the motive form of the heavens and the agent cause that « imparts to them » their everlasting motion 226. As such, the Intelligence is not a cause external to the celestial soul, but it is the very form through which the soul acts and moves and desires. It is the agent-form through which the

222 Averroes denies that the heavens, as lacking a material form, have a potency to be moved or not moved ; Commentum magnum super libro De celo et mundo, II, 12, t.c. 71, p. 410, 83-91. See also above at n. 157-158, as well as n. 224 below.

223 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 8, t.c. 44, p. 1652, 5-16. Cf. above, n. 157. 224 See above, at n. 149 ; 152 ; 160 ; cf. also n. 117 ; 181. 225 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 8, t.c. 44, p. 1648, 4-1659, 7. See H. A. Wolfson, « Averroes’

Lost Treatise on the Prime Mover », p. 421-28 ; H. A. Davidson, Alfarabi, Avicenna, and Averroes on Intellect, p. 227-229. For ‘agent’ used equivocally of an immaterial agent, to which the principle « from one comes only one » therefore does not apply, see Averroes, Tahafot at-Tahafot 3, p. 230, 9-16.

226 See above, at nn. 142 ; 146 ; 149 ; 175. For the identification of agent and mover in the first cause of the world, see Tahafot at-Tahafot 3, p. 172, 3-13 ; disc. 4, p. 264, 4-13.

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celestial soul causes its peculiar everlasting motion, and without which it cannot cause such motion. In this way immaterial Intelligence is one with the immaterial celestial soul, even if it is distinct from the soul taken in itself (which is « possible » and « receptive » of it) : intellect and intelligible are one. Given « agent-end identity », the Intelligence as agent and end is not a form other than the celestial soul’s conceptualization of the end and agent-desire. The Intelligence is only a final cause of the heavens by being conceptualized and desired by the motive intellect of the celestial soul. And, the Intelligence is thereby the very agent in the celestial soul’s immediate and everlasting moving of the spheres.

But, we may ask, if it is not possible to distinguish the efficient causality of the celestial soul from that of the Intelligence, is not one or the other redundant ? The answer is that we can distinguish in the soul what it contributes as an agent in itself from what it contributes as an agent through its Intelligence. There is no distinction (unless it be in disposition ?) between the agency of the Intelligence in causing everlasting celestial motion and the soul’s agency through the Intelligence. But the soul in itself contributes an agency that the Intelligence cannot. The soul is the efficient cause of the peculiar motion of finite speed, with a particular direction, in a determinate body (of which the soul is the essence). It does draw something from potency into act – not in the sense that there was a time before which there was no change and after which there was change – but because each part of each sphere is always in potency to being in another place, and the sphere’s potency is always being actualized by its celestial soul. The Intelligence does not, as Intelligence, draw this potency into act 227. But as conceived by the celestial soul, the Intelligence is the agent-form of the sphere’s being rotated forever 228. In this sense, its agency is different from the agency of the celestial soul, without either’s being redundant. The Intelligence moves an everlasting heavens only as an object of desire (which in

227 As Averroes puts it, were there no potency, there would be no agent (but were there no agent, nothing would be in act ; hence, all forms exist in a higher way in the prime mover, as artifacts in the artisan’s soul) ; Tafsīr mā ba‘d aì-ìabī‘at, Λ, 3, t.c. 18, p. 1505, 1-5. It follows that the Intelligence is properly the agent, not of the celestial soul, but of the motion of the heavens precisely as everlasting.

228 The same balance of extrinsic agent cause versus proximate, intrinsic cause appears in a difficult but important passage in which Averroes compares the separate power that is in the moved heaven and that is a source of everlasting motion to a sailor in a ship and to the human agent intellect, whereas the non-separate principle in the moved heaven (the source of circular motion, lacking contraries) resembles the human intellectus in habitu or the form of the human ; De separatione..., p. 126, 22-128, 10. Averroes responds to the question, how will a power that exists separate from the heavens rule them such that they are necessarily moved with a circular motion ? ibid. p. 124, 12-14.

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immaterial things moves as both agent and end), whereas the celestial soul through its object of desire moves the everlasting heaven by immediately changing it from potency into act in the category of place. Insofar as we must distinguish Intelligence and celestial soul, then, we can reject the view, as Averroes does in one place, that because the celestial body is eternal and has a soul, it has no need for a separate, extrinsic mover 229. « Separate, extrinsic mover » does not mean that it is yet another cause changing the first moved body from potentially to actually being in another position in its revolution, but it means that it is distinct from, necessary for, and acting within the operation of the first intrinsic mover 230.

D. The Solution : Astrophysical Clarification Subsequent to the Physics

Averroes holds that Natural Science, not Metaphysics, proves the existence of God. Yet, it is difficult to see how this conclusion is found in Aristotle’s Physics, as Averroes reads it. Nevertheless, the balance of evidence indicates, I maintain, that Averroes does think Physics VIII, 10 arrives at God, the first being in his cosmos. This fact emerges, first, from a retrospective examination of Averroes’ language. When Averroes writes that Chapter 10 proves more properly than before that the prime mover is not a body, when he concludes that it is « not a body or a power of a body », that it is outside matter and subsisting per se, his words have a technical precision which is not immediately apparent231. With them he refers to a cause of motion that is not the celestial soul – which soul in a loose sense is « in a body » – but to the Intelligence that is « external » to the soul, even though it acts « in it » as its intelligible form. For, the celestial soul, upon further physical analysis, turns out to be in itself finite in the duration of its power, and in itself « possible » with

229 Questions in Physics VII, p. 241, 12-13, quoted above, at n. 119. See also Commentum magnum super libro De celo et mundo, I, 3, t.c. 22, p. 46, 129-142, for the need in a proof of God’s existence to affirm an « extrinsic principle that is neither bodily nor a power in a body ». In ibid. I, 9, t.c. 100, p. 189, 62-65, Averroes identifies Aristotle’s reference there to « life » as an instance of his ambiguous references throughout either to the orb or to « the first cause » : that is, either to « life that is in the orb » or to « life that is outside the orb ».

230 Cf. Tafsīr mā ba‘d aì-ìabī‘at, Λ, 5, t.c. 24, p. 1529, 6-10, according to which the prime mover, although external to all proximate movers, is only such insofar as its form is in a way all forms. For other reflections on the relation of celestial intellects, see H. A. Davidson, « Averroes on the Active Intellect as a Cause of Existence », Viator, 18 (1987), p. 191-225, at 198-200 ; R. C. Taylor, « Averroes on Psychology and the Principles of Metaphysics », Journal of the History of Philosophy, 36 (1998), p. 507-523.

231 See above, at n. 69-70 ; 108 ; 111 ; 120 ; 149 ; 152-153 ; 161 ; 166 ; 175.

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respect to causing or not causing motion. The Physics’ Argument from Infinite Potency requires the existence of a separate Intelligence as a first cause of circular motion that is infinite in duration.

Accordingly, Averroes already in Physics VIII, 10 speaks of God as having been shown to be « in the heavens » as where his effects are, and repeated cross-references to Physics 8 treat the prime mover proved there as the ultimate first cause. The remark in Long Commentary on Metaphysics Λ, 7 is typical : « It has already been shown at the end of the eighth [book] of the Physics that it [the eternal substance here shown to move as something loved] is not moved and is separate from matter » 232. Nowhere does Averroes present the Physics’ prime mover, at least that of Chapter 10, as a subordinate cause, surpassed in subsequent argumentation. For Averroes, then, the Argument from Infinite Potency – not the argument of Chapter 6 for a first mover that is moved neither per se nor per accidens – concludes to the existence of the first cause or God.

At the same time, the Long Commentary on Physics VIII, 10 does not make clear how Averroes can be justified in regarding the prime mover there as the first cause in his cosmos, and not possibly a celestial soul. Only further reasoning not found in the Physics clarifies why Averroes’ cosmos requires two celestial causes in order to account for everlasting motion, why a celestial soul, or whatever is the proximate mover of the spheres, cannot suffice, and therefore how Physics VIII, 10 already implicitly surpasses such a mover. I have laid out that reasoning as the heart of Stage IV, having discovered it principally in two of Averroes’ treatises, the De substantia orbis and the Long Commentary on Metaphysics Λ, 7. But we should not suppose that the Prime Mover Argument is extended as if another science concludes to the first cause, or that it is completed by two separate arguments, one of which is in Metaphysics, as if Metaphysics arrives finally at the existence of the first cause. For Averroes, the Science of the Heavens, a part of Natural Philosophy clarifies what is meant by the Physics’ arrival at a first mover that is infinitely powerful such that it can cause everlasting motion. Averroes’ treatises grouped under the title De substantia orbis are meant to solve such special problems left from the Physics and De caelo, to fill a gap in Aristotle’s works, perhaps explained in lost writings 233. The treatises offer no reasoning to the existence of an infinite

232 Tafsīr mā ba‘d aì-ìabī‘at, Λ, 7, t.c. 41, p. 1626, 9-10. 233 De substantia orbis : Hebrew, chap. 1, 195-199, where Averroes suggests that he intends

the first treatise to replace Avicenna's treatise of a similar name. The De motu animalium was not translated into Arabic.

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power beyond that already found in Physics VIII, 10. Instead, they argue that the proximate mover of the heavens must be finite in strength, and therefore, as such, finite in the duration of its power. The further discussion of Metaphysics, arguing that the heavens and their proximate mover have the possibility of not causing motion, depends on the discussion of De substantia orbis. A cause entirely separate from the body of the sphere, concludes Averroes, must « impart » infinity of duration and necessity of causing motion to the proximate mover. Metaphysics goes on to show how the prime mover, whose existence was proved in Physics VIII, 10, is also the form and final cause of the cosmos, in addition to being agent cause, by being the intelligible form in the intellect of the celestial soul through which it moves. Thus, Metaphysics shows also in what way the prime mover is the cause of all things, even of immaterial principles.

In short, Stage IV is a clarification of the conclusion of Stage III rather than an extension of the argument, as if arriving at the existence of a mover not known in Physics. We may say that for Averroes, Physics arrives at the existence of God, the prime mover. How its reasoning achieves this goal is unclear without appeal to the supplemental reasoning of Astrophysics, a part of Natural Philosophy. At the same time, we should admit that Averroes did not concern himself with the question, how does Physics arrive at what cannot be a mere sphere soul ? He did not identify this as a question. The Long Commentary on the Physics is very faithful to the letter of Aristotle, which is itself underdetermined regarding the question 234. When the Commentator departs from the text, he is preoccupied with the philosophizing theologians and the theologizing philosophers. He is especially concerned with Avicenna’s affirmation of a God beyond the prime mover, from whom all things eternally emanate as existents possible in themselves. In a parallel error, materialist Avicennians affirm a necessary being that is not a substance separate from matter235. Averroes blames Philoponus and Alexander as the origin of Avicenna’s false turn (whereas Themistius emerges, at least on these issues, unscathed) : they inferred that a finite power must have finite existence. Nevertheless, Averroes does

234 The line of reasoning of the Long Commentary on the Physics and the De separatione… to the effect that what is not in a body is neither finite nor infinite in power, as according to Premise (11), may seem to obscure or even contradict Averroes’ doctrine on the celestial soul as finite in the De substantia orbis and Long Commentary on the Metaphysics. See also above, at n. 95 ; 99. This premise may stem from an early stage of Averroes’ thought. Nevertheless, there now appears a way to interpret Premise (11) so as to harmonize it with the rest: perhaps by what is « not in a body » in the premise, Averroes means to exclude the celestial soul, as elsewhere ; whereas his mention of finite « immaterial movers » in Premise (9) includes the soul.

235 See above, at n. 116.

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have an answer to our question, which can be discerned in Stage IV: Physics VIII, 10 concludes to a prime mover that cannot be « in the body » as is a celestial soul (even though Avicenna is wrong about the way the soul is « in » the heavens). The texts force us to this conclusion. The Argument from Infinite Potency, in Averroes’ eyes, concludes to a cause of everlasting motion that cannot be a celestial soul. It is presumptuous to say, of course, that such a creative mind as Averroes would have solved the problem in the way that the available texts suggest, were he to have written a special treatise dedicated to the theme. But it does not follow that we should not reconstruct his answer based on what is available to us so as to understand the Commentator’s thought.

Conclusion

Aristotle’s texts on the prime mover leave his reader with conundrums. Books VII and VIII of the Physics apparently arrive at a first unmoved mover in the order of the efficient causality of motion. At the outset of Physics VII, 2, Aristotle even expressly admits that the argument rejecting an infinite series of moved movers does not succeed when the movers are considered to be moved only by final causes. Metaphysics Λ, 7 affirms unequivocally, however, that an unmoved mover moves as an object of desire and as a final cause. At the same time, nowhere in the course of his Prime Mover Argument does Aristotle explicitly introduce soul or a power of desire into the revolving spheres.

Averroes himself never thematizes these interpretive dilemmas as problems. If anything, he only appears to exacerbate them by affirming that the existence of the ultimate prime mover can be known only in Physics, not in Metaphysics. Nevertheless, when one lays out his account of the Prime Mover Argument as a whole, across his many works, one discovers a remarkably coherent, faithful, and creative reworking of the pieces of Aristotle’s puzzle, albeit in a monotheist context. It should not surprise us that the greatest names of Averroes scholarship have disagreed on how to piece together Averroes’ own cosmology. Very often the disagreements arise by focusing on one work to the exclusion of others. Consider the linguistic and textual difficulties involved in reading the Long Commentary on the Physics and the De substantia orbis, with their forest of arguments, together with the Long Commentary on the Metaphysics – which never quite discloses what we hope to find, unless it be with the image of the baths – all the while not neglecting the Tahāfut at-Tahāfut. The reader, aware of the number of remaining commentaries that lie unedited in manuscript form, knows how idle are any claims

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to a definitive exposition. One can only hope that a sketch of the whole will allow for a renewed interest in returning to the parts. That there must be a whole, however, seems more certain in the case of Averroes than in the case of Aristotle. He does intend his commentaries to be definitive expositions of the sciences, as if all that one needs is presented therein. The scientific character may even suggest why it is important for him to revise his original text in light of new discoveries in subsequent treatises. It may also explain why, despite some starts and stops, a unity to the whole emerges.

On Averroes’ account, the affirmation of celestial ensoulment is inescapable in the Prime Mover Argument given a foundational premise in Physics VII and VIII, defended both systematically and textually : Every external mover must be a moved mover. As a result, the denial of a per se infinite series of moved movers leads to the affirmation of a first mover moved by itself – by its soul. This affirmation provides the key piece around which the rest of the puzzle unfolds. Ensoulment, moreover, is not subsequently excluded with the arrival in Physics VIII, 6 at a prime mover that is neither per se nor even per accidens moved. Thanks to Averroes’ invention of an immaterial, non-hylomorphic soul, not subsistent in the sphere, the intrinsic origin of perpetual rotation is guaranteed. Only in the final stage of the argument proper is the celestial soul surpassed as a candidate for « ultimate mover » : in Physics VIII, 10’s Argument from Infinite Potency. As other treatises make clear, a soul « in » a body must be of finite power in strength, and therefore in duration, and so must have the possibility not to cause motion. Therefore, the prime mover that causes infinite duration in Physics VIII, 10 must be a separate Intelligence, in no way « in » the body of the heavens, as is the soul. This prime mover is, in turn, shown in the Metaphysics to move as form and end, conceptualized and desired by the celestial soul as the form through which it effects everlasting motion 236.

236 Special thanks go to Deirdre Dempsey for consultation on rabbinic Hebrew, to Kirstin Carlson and Stuart Ditsler for research assistance, and to my colleague Richard Taylor, sine quo nihil.