Commentary Aristotle Physics
Lecture 9
Refutation of Anaxagoras’ opinion about an infinite number of principles
The theory of Anaxagoras that the principles are infinite in multitude was probably due to his acceptance of the common opinion of the physicists that nothing comes into being from non-being.
For this is the reason why they use the phrase “all things were together,” and the coming into being of such and such a kind of thing is reduced to change of quality, while some spoke of combination and separation.
Moreover, the fact that the contraries proceed from each other led them to the conclusion.
The one, they reasoned, must have already existed in the other, for since everything that comes into being must arise either from what is or from what is not, and it is impossible for it to arise from what is not (on this point all the physicists agree), they thought that the truth of the alternative necessarily followed, namely, that things come into being out of existent things—that is, out of things already present but imperceptible to our senses because of the smallness of their bulk.
So they assert that everything has been mixed in everything, because they saw everything arising out of everything.
But things, as they say, appear different from one another and receive different names according to the nature of the particles that are numerically predominant among the innumerable constituents of the mixture.
For nothing, they say, is purely and entirely white or black or sweet, bone or flesh, but the nature of a thing is held to be that of which it contains the most.
Now the infinite as infinite is unknowable, such that what is infinite in multitude or size is unknowable in quantity and what is infinite in variety of kind is unknowable in quality. But the principles in question are infinite both in multitude and in kind. Therefore it is impossible to know things that are composed of them, for it is when we know from what and from how many it is composed that we suppose we know a complex.
Further, if the parts of a whole may be of any size in the direction either of greatness or of smallness (by “parts,” I mean components that are actually present and into which a whole can be divided), it is necessary that the whole thing itself may be of any size. Clearly, therefore, since it is impossible for an animal or plant to be indefinitely big or small, neither can its parts be such, or the whole will be the same. But flesh, bone, and the like are the parts of animals, and the fruits are the parts of plants. Hence it is obvious that neither flesh, bone, nor any such thing can be of indefinite size in the direction either of the greater or of the less.
Again, according to the theory, all such things are already present in one another and do not come into being, but are constituents that are separated out, and a thing receives its designation from that which abounds in it. Further, anything may come out of anything—water by separation from flesh and flesh from water.
Hence, since every finite body is exhausted by the repeated abstraction of a finite body, it seems obviously to follow that everything cannot subsist in everything else.
For let flesh be extracted from water, and again, let more flesh be produced from the remainder by repeating the process of separation; then, even though the quantity separated out will continually decrease, still it will not fall below a certain magnitude.
If, therefore, the process comes to an end, everything will not be in everything else (for there will be no flesh in the remaining water); if, on the other hand, it does not, and further extraction is always possible, there will be an infinite multitude of finite equal particles in a finite quantity—which is impossible.
Another proof may be added: since every body must diminish in size when something is taken from it, and flesh is quantitatively definite in respect both of greatness and smallness, it is clear that no body can be separated out from the minimum quantity of flesh, for the flesh left would be less than the minimum of flesh.
Finally, in each of these infinite bodies, there would be already present infinite flesh and blood and brain—having a distinct existence, however, from one another, and no less real than the infinite bodies, and each infinite. This is contrary to reason.
The statement that complete separation never will take place is correct enough, for passions are indeed inseparable. If, then, colors and states had entered into the mixture, and if separation took place, there would be a “white” or a “healthy” that was nothing but white or healthy, that is, was not the predicate of a subject.
So, the intellect which seeks these impossibilities is absurd, if he truly wishes to separate such things and it is impossible to do so, both in respect of quantity and of quality—of quantity, because there is no minimum magnitude; and of quality, because passions are inseparable.
Nor is Anaxagoras right about the generation of things of the same species. It is true there is a sense in which clay is divided into pieces of clay, but there is another in which it is not. Water and air are and are generated from each other, but not in the way in which bricks come “from” a house and again a house “from” bricks.
And it is better to assume a smaller and finite number of principles, as Empedocles does.
58. Having set forth the opinions of the natural philosophers concerning the principles, he here pursues one of these opinions, namely, that of Anaxagoras. For this opinion seemed to assign a common cause for all the species of motion.
The discussion is divided into two parts.
In the first part, he sets forth Anaxagoras’ argument;
in the second part, he raises objections against it, at “now the infinite” (187b7; [64]).
Concerning the first part, he makes three points.
First, he sets forth those things that Anaxagoras supposed and from which he argued.
Second, at “the one, they reasoned” (187a32; [62]), he sets forth the order of his argument.
Third, at “but things, as they say” (187b2; [63]), he sets forth Anaxagoras’ response to a certain tacit objection.
59. Anaxagoras assumed two things from which he argued. The first of these is a point that is assumed by all of the natural philosophers, namely, that nothing comes to be from nothing. And Aristotle says that, because of this, Anaxagoras seemed to have held the opinion that the principles are infinite. For he accepted as true the common opinion of all philosophers of nature, namely, that what simply is not in no way comes to be. For they assumed this as a principle and then developed their different opinions.
60. Lest they should be forced to hold that something new comes to be that previously was in no way at all, some held that all things from the beginning existed together, either in some one confused state, as Anaxagoras and Empedocles held, or in some material principle, such as water, fire, and air, or some intermediate between these.
And, in accordance with this, they posited two modes of production.
Those who held that all things preexisted together as in one material principle said that coming to be is nothing other than being altered. For they said that all things come to be from that one material principle through its condensation and rarefaction.
Others, however, who held that all things preexisted together in some one confused state and mixture of many, said that the coming to be of things is only a joining together and a separation.
All of these philosophers were deceived because they did not know how to distinguish between potency and act. For being in potency is, as it were, a mean between pure non-being and being in act. Therefore, those things that come to be naturally do not come to be from non-being simply, but from being in potency, and not, indeed, from being in act, as they thought. Hence things that come to be did not necessarily preexist in act, as they said, but only in potency.