3 Avicenna
3.3 Physics
3.3.2 Motion and positional motion
To understand where particularization comes from, we must start with motion in a brief introduction.
Interestingly enough, in the particularization of the world spatial position has a fundamental role play. As we will see later, the source of multiplicity is matter, but the diversity of the material world cannot derive from prime matter, namely, only from pure potentiality. Avicenna, indeed, turns back to the celestial motions to explain how differentiation, in general, comes to be. In the next few lines, we will briefly consider its implications.
Avicenna follows Aristotle in the definition of motion that it is the first perfection of what is in potency, inasmuch as it is in potency.419 Then Avicenna distinguishes between two meanings of motion. The first is taken as a process that starts from the starting point of motion and ends at the final point; this is an intelligible, continuous process that exists only in imagination.420 On the other hand, the motion that exists actually in the moving thing is an intermediate state
417 Dhanani, 1994, 62–66.
418 Taʽlīqāt, (B) 98–99; (M) 275–276 [467].
419 Samāʽ, 83, 5; Aristotle, Physics, 201a10–11.
420 Samāʽ, 83, 19–84,
103 (ḥāla mutawassiṭa) between the two limits of motion.421 It is not a static state that it would actually exist there for a moment; rather, it just transgresses a distance in a given moment.422 This presupposes Avicenna’s account of dynamic instant.423
According to the well–known Aristotelian teaching, there are three categories in which motion occurs strictly speaking: quality, quantity, and place.424
Avicenna, however, adds the category of position to this set.425 This solution is a response to an old debate on whether the cosmos as a whole is in place or not.426 What most concerns us here is the positional motion that makes motion possible for the sphere. The main problem with this kind of motion that position has no opposite, and in consequence, the motion would be inconceivable in the Aristotelian sense.427 Avicenna simply admits that two distinct positions, although not being real opposites, are not far from being opposites.428 To explain the celestial motion, there is no need for real opposites, however.429
The proximate cause of the heavenly motion is the particular will of the celestial soul. This particular will is represented in the positional motion that each particular will moves the celestial body to a certain position, and then to another position. It practically means rotation that every part moves, but not all the parts as a whole.430 Thus, even though the parts change their position concerning the other parts, the whole is still unmoved with regard to its place. It is like a ball rotating on the finger of the basketball player.
However, every motion starts from one point and ends at another: in this case these points are two distinct points – determined by supposition: they may be either identical, in which case, the circle simply rotates around its axis and returns to the starting point during a certain period of time, or two distinct points. In this latter case, this point serves as the starting point at time A and serves as the end at time B.431
In Avicenna’s view, time is the measure of circular motion concerning priority and posteriority.432 Avicenna has lengthy discussions to show the quiddity of time,433 for us, it
421 Samāʽ, 84, 9–12.
422 Samāʽ, 84, 10–14.
423 On this see McGinnis, 2010, 61–64.
424 Aristotle, Physics, 226a23–25.
425 al-Samāʽ, 103, 11–104, 6.
426 For the history of this debate see McGinnis, 2002.
427 Compare Aristotle, On the Heavens (I.4), 270b27–271a34.
428 Samāʽ, 103, 11–12.
429 Samāʽ, 103, 12.
430 Samāʽ, 105, 5-8.
431 Ilāhiyyāt, 385, 13–386, 5; Samāʽ, 91, 16–92, 1. McGinnis, 2002, 153–154.
432 Najāt, 231; McGinnis, 2006, 71.
433 Samāʽ, 155–160.
104 suffices to say that as being the measure of circular motion, the source of temporal differentiation equally goes back to positional motion, and different positions in the sphere.
What is the ultimate source of particularity in the motion of the spheres?
Avicenna is following the former tradition that the proximate cause of celestial motion is the desire to be similar to the First Principle. Even though this desire is not directed towards motion at the first intention, that is, it is not the motion itself, which would be the main goal, but the similarity to the First. The celestial body receives the infinite force, insofar as celestial soul intellects the First, in such a way that its light shines upon it forever. Since the First has infinite power, the celestial soul becomes as if it had infinite power, but it has not. It is only due to the intellected object, the First. The celestial body is perfect in its substance since there is no potentiality left in its substance, nor its quantity or quality. The only feature which may include potentiality is in its place and position.434
This idea implies that the celestial body, which has matter and in consequence, extension, is perfectly simple. No feature is potential in it, except for its place. As Avicenna explains:
[This is because] the celestial body in its substance has no position or place more proper, than other position or place in its extension. This is because no part of the circle of the sphere or planet is more likely (awlā) to be in a particular position. If one part of the celestial body is in one part of the circle, then its other part is potentially not in the other part. In this sense, there is one aspect where the celestial substance is in potentiality, in respect of its position.435
What we see here is, again, similar to the argument of particularization as it appears in the Kalām-works of the time: there are several possibilities for a given event, and none of the possibilities is more likely than the other. In this case, something, a preponderating or specializing factor is needed: as we saw above, this argument was usually used by Muslim theologians to infer to the existence of God.436 However, Avicenna simply aims to show here that the celestial body does not move by itself in either direction. Its soul will be the reason why it moves in a particular direction. As to the question of why it moves at all, Avicenna refers to the perfection of God and the imperfection of the celestial substance.
The similarity to the First principle is utmost perfection, which lasts forever; but it is not possible for the celestial substance to reach it, that is, it will never be similar to it exactly; thus, it always strives for it: the principle of this desire is what the celestial substance intellects from the First.437
434 Ilāhiyyāt, 389, 10–14; Mabda’, 60–61.
435 Ilāhiyyāt, 389, 15–390, 1; Mabda’, 61.
436 See my article on the Particularization argument, Lánczky, 2016.
437 Ilāhiyyāt, 390, 5.
105 Avicenna uses the term mukhaṣṣiṣ in this context, insisting that two concept-formations and two wills must differ somehow, and it cannot be unless there is a reference to an individual specializing factor (istinād fīhi ilā mukhaṣṣiṣ shakhṣī) to which it may be related.438
The source must be something that involves divisibility and potential multiplicity – and this is imagination, a psychic faculty imprinted in the matter.
At this point, it is worth to make an epistemic outlook: one of Avicenna’s main arguments for the immateriality, and in consequence, the eternity of the human intellects that they are not divisible.439 We have also seen how spatially extended things are placed only in the estimation or in any other psychic faculty that is imprinted in the matter.440 The huge topic of God’s knowledge of particulars also belongs here: universal, intellectual knowledge cannot grasp particulars: spatio-temporal differentiation has no “place” in the intellect.
Searching for the cause of motion in case of the celestial spheres, Avicenna expressis verbis refers to Aristotle De Anima in the al-Mabda’ wa-l-Maʽād:
The Philosopher has already implied a principle of some use in this topic since he said: to that, I mean the theoretical intellect, [belongs] the universal judgment, as for this, I mean the practical intellect [belongs] the particular deeds and particular intellections. This is not only in our will but also in the will from which the motion of the sky is originated.441
Here Avicenna clearly distinguishes between the theoretical and practical intellects, whereas the former makes only universal and the latter particular judgments. He infers this tenet to the celestial souls.442
Avicenna makes clear that the universal will cannot cause motion: the universal will, insofar as universal does not single out any particular motion, because its relation (nisba) to the effect, the motion, is one, even if there are more universal wills one after the other. There is nothing that would preponderate the motion from A to B, more likely that the motion from B to A. As Avicenna puts it, their relation and non-relation to their principle are one; it is not distinguished nor preponderated, and whatever does not necessarily follow from its cause, does not exist.443 That is if an intellectual will wants a motion from A to B, and then from B to C, then A, B, C are of the same species, and there is nothing that singles out (yuʽayyin) any one of them more likely than the other. It should be due to a particular, psychic will.444
438 Ilāhiyyāt, 386, 6–7.
439 Nafs, 187,11–190, 12.
440 See in our section on Logic, Avicenna’s square example.
441 Mabda’, 29.
442 The passage clearly echoes Aristotle, On the Soul, 434a17–21.
443 Ilāhiyyāt, 385, 4–12; Mabda’, 28–29.
444 Ilāhiyyāt, 385, 13–386, 2.
106 Even though the intellectual concept-formation can think on the whole process by a universal will, which corresponds, in this case, to the circular motion, it cannot think on any particular point on the arc. It can only think on the universal “point” that equally applies to all the points of the circle. To designate one particular point – which is a prerequisite of motion – one has to turn to the soul and sense-perception, for the aforementioned epistemic reasons: for Avicenna, the representation of spatial difference requires matter, that is, material psychic faculties.
The problem is similar to the definability of individuals. The dichotomy of the universal-particular will is an epistemic problem, just like the logical identification of individuals. To pick up one individual point, one has to relate it to an already individuated element.445 Here also, Avicenna uses practically the same toolkit: he insists that it must be related to an individual specializing factor (istinād ilā mukhaṣṣiṣ shakhṣī yuqāsu bihā).446
In other words, the motion of the celestial spheres is positional motion. The ultimate source of the diversity of rotations is the imagination of the celestial soul that becomes manifested in the positional motion. That is, the first item of difference is a spatial spot, insofar as one piece of motion starts from one and ends in another. In this context also, it is a spatial position that explains the physical distinction among the different rotations. The fact that there may be multiple positions is due to the celestial matter: here again, the source of multiplicity is matter.
The source of the distinct points in the matter is spatial position.