Commentary Aristotle Physics
Lecture 3. Arguments against Anaxagoras and Empedocles
It is clear then that motion cannot have existed at one time and not at another:
in fact, such a view can hardly be described as anything else than fantastic.
And much the same may be said of the view that such is the ordinance of nature and that this must be regarded as a principle.
And this seems to be the view of Empedocles when he says that the constitution of the world is of necessity such that love and strife alternately predominate and cause motion but rest in the intermediate period of time.
Probably also those who, like Anaxagoras, assert a single principle (of motion) would hold this view to be true.
But that which is produced or directed by nature can never be anything disorderly, for nature is everywhere the cause of order.
Moreover, there is no ratio in the relation of the infinite to the infinite, but order always means ratio.
But, if we say that there is first a state of rest for an infinite time, and then motion is started at some moment, and that the fact that it is this rather than a previous moment is of no importance, and involves no order, then we can no longer say that it is nature’s work.
For if anything is simply of a certain character naturally, either it is so invariably and not sometimes this character and sometimes another (for instance, fire, which travels upwards naturally, does not sometimes do so and sometimes not) or there is a ratio in the variation.
It would be better, therefore, to say with Empedocles and anyone else who may have maintained such a theory as his that the universe is alternately at rest and in motion, for in a system of this kind, we have at once a certain order.
But, even here, the holder of the theory ought not only to assert the fact; he ought to explain the cause of it.
He should not make any mere assumption or lay down any gratuitous axiom, but should employ either inductive or demonstrative reasoning.
The love and strife postulated by Empedocles are not in themselves causes of the fact in question, nor is it of the essence of either that it should be so—the essential function of the former being to unite, of the latter to separate.
If he is to go on to explain this alternate predominance, he should adduce cases where such a state of things exists, as he points to the fact that, among mankind, we have something that unites men, namely love, while, on the other hand, enemies avoid one another.
Thus, from the observed fact that this occurs in certain cases comes the assumption that it occurs also in the universe.
Then, again, some argument is needed to explain why the predominance of each of the two forces lasts for an equal period of time.
But it is a wrong assumption to suppose universally that we have an adequate first principle in virtue of the fact that something always is so or always happens so.
Thus, Democritus reduces the causes that explain nature to the fact that things happened in the past in the same way as they happen now, but he does not think fit to seek for a first principle to explain this “always.”
Therefore, while his theory is right insofar as it is applied to certain individual cases, he is wrong in making it of universal application.
Thus, a triangle always has its angles equal to two right angles, but there is nevertheless an ulterior cause of the eternity of this truth, whereas first principles are eternal and have no ulterior cause.
Let this conclude what we have to say in support of our contention that there never was a time when there was not motion, and never will be a time when there will not be motion.
991. After presenting the reasons showing that motion always existed, the Philosopher here gives arguments against Anaxagoras and Empedocles, who posited the contrary.
About this, he does two things: first, he gives an argument against their position; second, he gives an argument against the argument they presupposed, at “and much the same” (252a5; [992]).
He says first (252a4) that, since it has been shown that motion always exists, it is wrong to say, as Empedocles and Anaxagoras did, that, at some time, motion exists, and at another time, it does not, for to make such a claim is a figment, because it has no basis. Something stated without a reason or the support of divine authority seems, indeed, to be a fiction. However, divine authority is stronger than human reason, much more indeed than the argument of a philosopher is more valuable than the weak argument some child might give. Therefore, what is held by faith, even though it be believed without an argument, is not a figment of the mind, because we believe on the divine authority approved by miracles—works that God alone can produce.
992. Then, at “and much the same” (252a5), he objects against the argument on which they rested.
About this, he does three things: first, he suggests that their argument is unsuitable; second, he shows that it is more unsuitable according to the position of Anaxagoras than according to the position of Empedocles, at “but that which is produced” (252a11; [993]); third, he shows that, even according to Empedocles’ opinion it is unsuitable, at “but, even here, the holder” (252a22; [994]).
He says first (252a5) that it also seems a fiction that anyone, positing that motion at one time exists and at another time does not, should give as his reason that this is so because it is natural for it to be that way and then add that this statement must be accepted as a principle.
Now that is what Empedocles seems to say, namely, that the situation whereby, during one period of time, things maintain friendship and, during another, are ruled by discord that sets things in motion, while they are at rest in the interim, is due to a sort of necessity in things.
That is like saying that the reason that heat warms is that it has to be that way, and the fact that heat warms should then be accepted as a principle.
This is exactly what Empedocles does when he takes as a principle that it is due to an ordinance of nature that things are at one time being moved by friendship, at another time moved by discord, and at another time are at rest.
Perhaps Anaxagoras, too, and others who posit one active principle would speak in a similar vein, namely, that we must accept as a principle that motion began to exist after not existing for an infinite period of time.
993. Then, at “but that which is produced” (252a11), he shows that Anaxagoras used this argument in a more unsuitable way than did Empedocles. For it is clear that, when something is laid down as a principle, it should be accepted as being according to the nature of a thing: that is, that the nature of a thing is such that such a thing belongs to it. Thus, we accept the principle that the whole is greater than its part because it is the very reason and nature of a whole that it exceed the quantity of a part. Hence, when Empedocles says that it is natural that it be that way, he gives us to understand that it should be accepted as a principle. Anaxagoras would have said the same, although he did not express it.
But it is clear that no natural thing or anything that belongs to things naturally can exist without order, because nature is a cause of order. For we see that nature in its works proceeds in an orderly fashion from one thing to another. Therefore, whatever does not possess order is not according to nature and cannot be called a principle.
But two infinites have no order one to the other, because there is no ratio between one infinite and another, while every order is a kind of ratio.
Accordingly, it is evidently not a work of nature that things rest for an infinite time and later begin to be moved for an infinite time without there being, between this time and that, any difference to explain why motion comes to be now rather than before—any more than it is a work of nature not to assign some other order between the two things such that, when one fails, the other begins and motion comes to be, as Anaxagoras posited.
These are not works of nature, because whatever is in nature either is always simply, that is, always the same and not sometimes this way and then that way (as fire always moves upwards), or is not always the same for some reason (as, for example, animals do not always continue growing, but reach a point when they start to decrease—and for this there is a reason).
Accordingly, it does not seem to be according to nature that things be at rest for an infinite time and later begin to be moved, as Anaxagoras assumed.
Hence, it is better to say, as Empedocles said—and those who believed as he—that the whole universe is at rest in one part of time and in motion at another, for in this case, at least there would be order, for there can be a ratio between one finite and another.
It should, however, be considered that the tenet of our faith is not akin to Anaxagoras’ position, for we do not assume before the world any infinite reaches of time that have to be related to a later time. Rather, before the world began, only the simple eternity of God existed, as was said, and that is outside the genus of time.
994. Then, at “but, even here, the holder” (252a22), he shows that the above-mentioned argument does not work for Empedocles’ position either.
First, he explains the proposition;
second, he rejects a false interpretation, at, but it is a wrong (252a32; [995]).
He says first (252a22) that, even the holder of Empedocles’ theory ought not only assert the fact, but should also explain the cause of his statement and not go beyond what is required by the cause he assigns.
Nor should he accept anything as an axiom, that is, as a principle without a reason; rather, whatever is accepted as a principle should be explained either by induction, as is done in the case of natural principles based on sense experience, or by demonstration, as in the case of those principles that are proved by prior principles.
But Empedocles does not do that. Granted that he posits love and strife as causes, yet it is not the property of love or hostility that one should cause motion after the other. For it is not in the account of love to be changed into hostility, or vice versa, though it is in the account of love to gather and in the account of hostility to scatter.
But, if it is further determined that, at one time, the one gathers and, at another time, the other scatters, it must be further made clear by definite instances in which this occurs. For example, that friendship gathers and discord scatters is manifested among men, since men are united by the former but fly from one another by the latter. So Empedocles supposed that this is what happens in the whole universe, because it seems to happen in certain cases. But there needs to be another argument to show that that, according to equal periods, friendship and discord should move successively, since that is not seen to happen among men.
995. Then, at “but it is a wrong” (252a32), he rejects a false assumption. For someone could believe that whatever is eternal has no cause, since whatever we observe as being caused among us is something that begins newly to be. Consequently, it seemed to some that, when a discussion reached something that always existed, there was no need to inquire any further for a cause or a reason. In this vein, Empedocles could say that friendship and discord had always caused motion according to equal times, and therefore no reason for it need be sought. But Aristotle disproves this by saying that it is wrong to suppose that we have an adequate first principle in virtue of the fact that something always is so or always happens so. In this way, Democritus reduced all the causes that explain nature to something existing always: he assigned a principle for things that begin newly to be, but would not look for a principle of what has always been. Now, this is true in some things and not in others. For it is clear that a triangle always has three angles equal to two right angles, but even of this eternal passion there is a cause other than itself. But some things are indeed eternal that do not have a cause, such as principles.
996. Very special attention should be paid to what is here said, because, as is mentioned in Metaphysics 2, the arrangement of things in existence and in truth is the same. Therefore, just as some things are always true and yet have a cause of their truth, so Aristotle understood that there are some eternal beings—namely, the heavenly bodies and separated substances—that nevertheless have a cause of existence. From this, it is evident that, although Aristotle posited a world that was eternal, he did not believe that God is only the cause of the world’s motion, and not of its existence, as some maintained.
Finally, he concludes his main proposition with a summary. And he says that these things have been said to show that there never was a time when there was not motion and that there will never be a time when there will not be motion.