LECTURE 14 (199 a 34-b 33)

HE DEMONSTRATES THAT NATURE ACTS FOR AN END FROM THE EVIDENCE FROM WHICH SOME CONCLUDE TO THE OPPOSITE POSITION

             261. After the Philosopher has shown by appropriate arguments that nature acts for the sake of something, he here intends to make this clear by destroying those things through which some embraced the contrary position.

             This section is divided into three parts according to the three things by which some seem to be moved to deny that nature acts for an end. The second part begins where he says, 'But the person . . .' (199 b 14).

The third part begins where he says, 'It is absurd . . .' (199 b 26).

             262. The first thing by which some seem to be moved to deny that nature acts for an end is the following. Sometimes we see things happen otherwise [than is customary], as happens in the case of monsters which are the errors of nature. Whence Empedocles held that at the beginning of the constitution of things certain things were produced which did not have this form and this order which is now commonly found in nature.

             263. He brings forth four arguments to overcome this difficulty.

             First he shows that although art acts for the sake of something, still in things which are made by art error occurs. For sometimes the grammarian does not write correctly, and the doctor prescribes a drink as a medicinal potion incorrectly.

             Hence it is clear that error occurs also in things which are by nature, even though nature acts for the sake of something. Of the things which are made by art for the sake of something, some are made according to art and are made correctly. There are other things, however, in which the artisan fails, not acting according to his art, and in these cases error occurs, even though the art is acting for the sake of something. For if art does not act for a determinate end, then there would be no error no matter how the art was performed. For the operation of the art would be equally related to all things. The very fact, then, that there happens to be error in art is a sign that art acts for the sake of something. The same thing also happens in natural things in which monsters are, as it were, the errors of nature acting for the sake of something insofar as the correct operation of nature is deficient. And this very fact that error occurs in natural things is a sign that nature acts for the sake of some thing.

             The same thing is true of those substances which Empedocles said were produced at the beginning of the world, such as the 'ox-progeny', i.e., half ox and half man. For if such things were not able to arrive at some end and final state of nature so that they would be preserved in existence, this was not because nature did not intend this [a final state], but because they were not capable of being preserved. For they were not generated according to nature, but by the corruption of some natural principle, as it now also happens that some monstrous offspring are generated because of the corruption of seed.

             264. He gives the second argument where he says, 'Further, seed must have . . .' (199 b 8). The argument is as follows.

             Wherever there are determinate principles and a determinate order of proceeding, there must be a determinate end for the sake of which other things come to be. But in the generation of animals there is a determinate order of proceeding. For it is necessary that seed come to be first, and there is no animal which exists immediately from the beginning. And the seed itself is not immediately hardened, but in the beginning it is soft and tends toward perfection in a certain order. Therefore, there is a determinate end in the generation of animals. Therefore, monsters and errors do not occur in animals because nature does not act for the sake of something.

             265. He gives the third argument where he says, 'Again in plants . . .' (199 b 9). The argument is as follows.

             Although nature acts for the sake of something in regard to plants as well as animals, this is less clear. Fewer things can be inferred from the operations of plants.

             If, therefore, monsters and errors occur in animals because nature does not act for the sake of something, this should be even more true of plants. As the 'man headed ox-progeny' occurs in animals, does there also occur in plants an 'olive-headed vine progeny', i.e., half olive and half vine? It seems absurd to say that these things occur. Nevertheless this must be so if in regard to animals it is true that nature does not act for the sake of something. Therefore, in regard to animals it is not true that nature does not act for the sake of something.

             266. He gives the fourth argument where he says, 'Moreover, among the seeds . . .' (199 b 13). The argument is as follows.

             As animals are generated by nature, so also are the seeds of animals. If, therefore, what occurs in the generation of animals happens in any way whatsoever, and not by nature, as it were, acting for a determinate end, then the same would be true of seeds, i.e., that any sort of seed would be produced by any sort of thing. This is obviously false. Hence, the first [supposition] is also false.

             267. Next where he says, 'But the person . . .' (199 b 14), he destroys the second point by which some were moved to hold that nature does not act for the sake of something.

             This seemed true to some because things which happen naturally seem to proceed from the prior principles, which are the agent and the matter, and not from the intention for an end.

             But Aristotle shows the contrary. He says that one who speaks in this manner, i.e., one who says that nature does not act for the sake of something, destroys nature and the things which are according to nature. For those things are said to be according to nature which are moved continuously by some intrinsic principle until they arrive at some end--not to some contingent end, and not from any principle to any end, but from a determinate principle to a determinate end. For progress is always made from the same principle to the same end, unless something impedes it. However, that for the sake of which something is done sometimes happens to occur by fortune, when [that which is done] is not done for the sake of this. For example, if some stranger should come and leave after he has bathed, we say this was by fortune. For he did not bathe himself as if he had come for this purpose, since he did not come for this. Hence his bathing is accidental (for fortune is a per accidens cause, as was said above . But if this should happen always or in most instances to him who comes, it would not be said to be by fortune. But in natural things events occur not per accidens but always, unless something should impede. Hence, it is clear that the determinate end which follows in nature does not follow by chance, but from the intention of nature. And from this it is clear that it is contrary to the meaning [ratio] of nature to say that nature does not act for the sake of something.

             268. Next where he says, 'It is absurd . . .' (199 b 26), he destroys the third point by which some hold the opinion that nature does not act for the sake of something. For it seems to some that nature does not act for the sake of something because nature does not deliberate.

             But the Philosopher says that it is absurd to hold this opinion. For it is obvious that art acts for the sake of something, yet it is also obvious that art does not deliberate. Nor does the artisan deliberate insofar as he has the art, but insofar as he falls short of the certitude of the art. Hence the most certain arts do not deliberate, as the writer does not deliberate how he should form letters. Moreover, those artisans who do deliberate, after they have discovered the certain principles of the art, do not deliberate in the execution. Thus one who plays the harp would seem most inexperienced if he should deliberate in playing any chord. And from this it is clear that an agent does not deliberate, not because he does not act for an end, but because he has the determinate means by which he acts. Hence since nature has the determinate means by which it acts, it does not deliberate. For nature seems to differ from art only because nature is an intrinsic principle and art is an extrinsic principle. For if the art of ship building were intrinsic to wood, a ship would have been made by nature in the same way as it is made by art. And this is most obvious in the art which is in that which is moved, although per accidens, such as in the doctor who cures himself. For nature is very similar to this art.

             Hence, it is clear that nature is nothing but a certain kind of art, i.e., the divine art, impressed upon things, by which these things are moved to a determinate end. It is as if the shipbuilder were able to give to timbers that by which they would move themselves to take the form of a ship.

             Finally, he concludes by saying that it is clear that nature is a cause and that it acts for the sake of some thing.