Lecture 6 — Refutation of Plato's opinion of disordered motion before the world

433 The same difficulty is involved even if it is supposed, as we read in the Timaeus, that before the ordered world was made the elements moved without order. Their movement must have been due either to constraint or to their nature. And if their movement was natural, a moment's consideration shows that there was already an ordered world. For the prime mover must cause motion in virtue of its own natural movement, and the other bodies, moving without constraint, as they came to rest in their proper places, would fall into the order in which they now stand, the heavy bodies moving towards the center and the light bodies away from it. But that is the order of their distribution in our world.

434 There is a further question, too, which might be asked. Is it possible or impossible that bodies in unordered movement should combine in some cases into combinations like those of which bodies of nature's composing are composed, such, I mean, as bones and flesh? Yet this is what Empedocles asserts to have occurred under Love. 'Many a head', says he, 'came to birth without a neck.'

435 The answer to the view that there are infinite bodies moving in an infinite is that, if the cause of movement is single, they must move with a single motion, and therefore not without order; and if, on the other hand, the causes are of infinite variety, their motions too must be infinitely varied. For a finite number of causes would produce a kind of order, since absence of order is not proved by diversity of direction in motions: indeed, in the world we know, not all bodies, but only bodies of the same kind, have a common goal of movement.

436 Again, disorderly movement means in reality unnatural movement, since the order proper to perceptible things is their nature. And there is also absurdity and impossibility in the notion that the disorderly movement is infinitely continued. For the nature of things is the nature which most of them possess for most of the time. Thus their view brings them into the contrary position that disorder is natural, and order or system unnatural. But no natural fact can originate in chance.

437 This is a point which Anaxagoras seems to have thoroughly grasped; for he starts his cosmogony from unmoved things. The others, it is true, make things collect together somehow before they try to produce motion and separation. But there is no sense in starting generation from an original state in which bodies are separated and in movement. Hence Empedocles begins after the process ruled by Love: for he could not have constructed the heaven by building it up out of bodies in separation, making them to combine by the power of Love, since our world has its constituent elements in separation, and therefore presupposes a previous state of unity and combination.

438 These arguments make it plain that every body has its natural movement, which is not constrained or contrary to its nature.

580. After disproving the opinion of Democritus and Leucippus on the motions of natural bodies, the Philosopher here disproves Plato's opinion on the same matter.

First with arguments;

secondly, with the saying of other philosophers, who are seen to have had better perception on this matter, at this is a point which (301a11; [585]).

581. Regarding the first he presents four arguments.

With respect to the first of which he says (300b16) that the same impossibility that happens to Democritus and Leucippus must recur, if anyone posits that before the world was made the elements out of which it is formed were being moved with a disorderly motion, as Plato writes in the Timaeus, recounting that, before the world was made by God, matter fluctuated without order. That the same impossibility recurs when this is posited he proves by adding that the disorderly motion by which the elements were being moved was either violent or according to nature, If violent, we are led back to the first position: hence the same impossibility recurs. But if the motion were according to nature, then we are contradicting our assumption. For it is assumed that the world was not yet existing, whereas, if the elements were being moved according to nature, then it is necessary to say the world was already existing, if one wishes to consider attentively. For since every motion, even according to Plato, is reduced to a first mover as to its cause, then, if the elements were in some way moved, it must be said that the first mover was moving himself according to nature. By first mover is here understood, not the absolutely first mover, which is utterly immobile, as. is proved in Physics VIII and in Metaphysics XII, but the first mover in the genus of natural movers, i.e., one that moves itself and is composed of mover and moved, as was proved in Physics VIII. But if we follow another reading, namely, the first mover must move the (first) moved according to nature, then it refers to the first mover moving absolutely, which is wholly immobile, which moves the first mobile. But no matter how "first mover" is understood, it must move according to nature, for it is not possible that what is beside nature precede what is according to nature, as is clear from the premises. Now, if the first mover moves naturally, necessarily the bodies which follow the motion of the first mover are not being moved by violence nor rest by violence in their appropriate places, but maintain the same order as now prevails, i.e., such that heavy bodies fall to the middle and rest there, but light bodies are borne from the middle and remain above. But this is the situation of the world as it now is; it follows, therefore, that the world would have been before it came into existence. It is not sound, therefore, to posit that the elements, before the world came to be, were being moved according to nature, but according to violence. And thus there follows the same impossibility as for Democritus and Leucippus.

582. The second argument he presents at there is a further question, too (300b25) and in one sense it leads to the same thing as the first, namely, that the world would exist before it came to be. But the first argument came to this conclusion by considering simple bodies; the present argument concludes to it by considering mixed bodies (for the disposition of both arises in the make-up of the world. He says therefore: If the elements, before the world was made, were being moved haphazardly, someone can ask whether the elements so moved were able to be mixed in such mixtures that natural bodies such as flesh and bones and so on, would result. If anyone should declare this not possible, it follows that the elements were not in utterly disorderly motion, since, namely, they could not be moved by any and all motions. For Empedocles, in positing that the elements are moved by friendship, said that such bodies were formed by the motion produced by friendship, in such a way, namely, that by the sole motion of the elements by friendship, for one there was generated flesh, for another, bone, for another a head, for another, hands. He further said that as a result of such a combination of elements through friendship, many heads were produced without a neck. If, therefore, it is maintained that it was impossible for these things to be produced, then the elements were not moved wholly without order. But if it were possible for these to be produced, then the disposition of the world was already completed, not only regarding simple bodies, but mixed bodies as well. It should be noted that the generation of heads without necks is, according to Empedocles, caused by friendship not in terms of a final product of its activity, but as part of the process whereby it gradually reduces the many to one, constituting mixed bodies from the elements.

583. The third argument he sets down at the answer to the view (300b31). It is not directed absolutely against Plato but in combination with the opinions of Democritus and Leucippus, who held that infinite indivisible bodies are being moved in infinite space. He says, therefore, that if those who posit infinite bodies being moved in infinite space accept Plato's position that before the world the elements were in haphazard motion, an impossibility would follow. For either all those infinite bodies would be being moved by one mover (i.e., according to species, e.g., by heaviness or lightness), or by an infinitude of movers. If by one, then they would have to be moved by one kind of local motion, for example, by upward motion or downward. Consequently, they would not be in haphazard motion, since there is already a certain order in the fact that all things are being moved to the same place. But if there were an infinitude of principles, all specifically different, it would follow that the species of motion would also be infinite. But this is impossible, according to things previously set down, in which it was shown that the species of motion are not infinite and indeterminate. Likewise, the same must be said if the principles of the motions are finite and the motions themselves finite—for, if there were finite species of motion, caused by finite principles, there would already be implied in them a certain order. For the disorder of motions does not arise from the fact that not all bodies are being moved to the same place, which is for there to be several species of motion, since even now, when, with the world existing, there is an ordered motion of bodies, not all bodies are being moved to one and the same place, but only those that are of the same genus, as all heavy bodies downward, He adds therefore by this argument that it is necessary to posit infinite motions if before the world was made bodies were being moved haphazardly.

584. He sets down the fourth argument at again, disorderly (301a4), and shows that the position in question contradicts itself. For to exist in disorder is nothing other than to exist beside nature. In sensible things it appears that order is their proper nature, since, namely, through its proper nature each of them is inclined to something definite. But this inclination is the order discerned in sensible things—for things are said to act or to move in a disorderly fashion when this happens contrary to the inclination of a thing's proper nature. From this it also appears that it is unfitting and impossible for a sensible thing to have a disorderly motion that is infinite, i.e., enduring for an infinite time, because, as has been said, a disordered motion is one contrary to nature. Now it appears that it belongs to the nature of each thing that it be found in many members of the same genus and most of the time. For what is found in just a few men is not said to be natural to man—for example, to be ambidextrous; nor what is true of some for just a short time—for example, to have a fever. But the natural is that which is found in the greater number and more frequently. Consequently, the Platonists come to assume two contraries at the same time, namely, that disorderly motion is according to nature, since it existed for an infinite time before the world, and that ordered motion, as well as the world constituted after the ordering of motion, are contrary to nature, since they have existed for a shorter time, even though nothing according to nature is as it happens, i.e., without a definite order.

It should be noted that the arguments of Aristotle go directly against the position of Plato, if the latter's words mean that there was a disorderly motion of the elements prior to the time that the world was made. But Plato's adherents say that this was not what he understood, but that all order in the motion of sensible things comes from the first principle, so that other things, considered in themselves, outside the influence of the first principle, are disordered. And according to this, Aristotle is not here objecting against Plato's sense, but against the words of the Platonists, lest they lead anyone into error.

585. Then, at this is a point which (301a11), he uses the saying of other philosophers to disprove the position in question, because they are seen to have had a better understanding of the matter. Concerning this, it should be noted that Democritus and Leucippus, as well as Plato, seem to have maintained two things in regard to bodies existing before the world: that they are in motion, and that they are segregated. As to the first, therefore, he says that, with regard to the constitution of the world, Anaxagoras seems to have surmised well. For he posited that the world began from bodies not previously moved. And this is more reasonable than to say that the world was made from bodies previously moved, because motion is a certain act of a thing existing in potency, and, consequently, is intermediate between first potency and first act. But in things that are being brought about, the beginning is taken from what is entirely in potency. Therefore it is more reasonable to fashion the beginning of the world from things wholly not in motion than from things moved.

As to the second he says that even those other philosophers who, in positing the beginning of the world, gathered together to some extent, (i.e., by saying that before the world came to be, all things were to some extent assembled into one) attempted to explain how things would then be set in motion and separated, in the founding of the world, as did Anaxagoras and also Empedocles. For it is not reasonable to produce the generation of the world out of things previously distant and in motion. For just as motion is a certain act, so also the distinction, or distance, between things results from their proper forms, according to which things are in act (for insofar as things are in potency they are not distinguished); and since generation strictly comes to be from what is in potency, it is therefore not reasonable to generate the world out of distinct and moved things. For this reason Empedocles, in explaining the first generation of the world, made no mention of friendship whose function is to assemble the scattered. For Empedocles could not explain the constitution of the heaven, i.e., of the world, by friendship, in such a way as to constitute it out of things previously separated, by making a gathering together of the previously scattered. For then it would follow that the world was constituted of things previously scattered, which is against the foregoing. Hence, because he used only strife in constituting the world, and strife's role is to scatter the assembled, the consequence is that the world, according to him, came from something one and gathered together out of many things.

Finally, in summary, he concludes (301a20) that it is plain from the foregoing that there is for each body a certain natural motion by which it is moved neither by violence nor beside its nature.