LECTURE 2 (184 b 15-185 a 19)

THE OPINIONS OF THE ANCIENT PHILOSOPHERS ABOUT THE PRINCIPLES OF NATURE AND OF BEINGS. IT DOES NOT PERTAIN TO NATURAL SCIENCE TO DISPROVE SOME OF THESE OPINIONS

             12. Having completed the preface in which it was shown that natural science ought to begin with the more universal principles, here, according to the order already stated, he begins to pursue those matters which pertain to natural science.

             This discussion is divided into two parts. In the first part he treats the universal principles of natural science. In the second part he treats mobile being in common (which is what he intends to treat in this book). This is taken up in Book III, where he says, 'Nature has been defined . . .' (200 b 12).

             The first part is divided into two parts. First he treats the principles of the subject of this science, that is, the principles of mobile being as such. Secondly he treats the principles of the doctrine. This he does in Book II, where he says, 'Of things that exist . . .' (192 b 8).

             The first part is divided into two parts. First he considers the opinions others have had concerning the common principles of mobile being. Secondly he seeks the truth concerning them, where he says, 'All thinkers, then, agree . . .' (188 a 18).

             Concerning the first part he makes three points. First he sets forth the different opinions of the ancient philosophers concerning the common principles of nature. Secondly, where he says, 'Now to investigate . . .' (184 b 25), he shows that it does not pertain to natural science to pursue some of these opinions. Thirdly, where he says, 'The most pertinent question . . .' (185 a 20), he considers these opinions, showing their falsity.

             Concerning the first part he makes two points. First he sets forth the different opinions of the philosophers concerning the principles of nature. Secondly, where he says, 'A similar inquiry is made . . .' (184 b 23), he shows that this same diversity exists with reference to the opinions of the philosophers concerning beings.

             13. He says, therefore, first of all, that it is necessary that there be one principle of nature or many. And each position has claimed the opinions of the philosophers.

             Some of them, indeed, held that there is one principle, others held that there are many. And of those who held that there is one principle, some held that it was immobile, as did Parmenides and Melissus, whose opinion he will examine below. Some, however, held that it was mobile, as did the natural philosophers.

             Of these, some held that air was the principle of all natural things, as Diogenes; others that it was water, as Thales; others that it was fire, as Heraclitus; and still others some mean between air and water, such as vapour.

             But none of those who held that there was only one principle said that it was earth because of its density. For they held that principles of this sort were mobile, because they said that other things come to be through the rarefication and condensation of certain of these principles.

             Of those who held the principles to be many, some held them to be finite, others held that they were infinite.

             Of those who held that they were finite (although more than one) some held that there were two, i.e., fire and earth, as Parmenides will say below. Others held that there were three, i.e., fire, air and water (for they thought earth to be in some way composed because of its density). Others, however, held that there were four, as Empedocles did, or even some other number, because even Empedocles himself along with the four elements posited two other principles, namely, friendship and strife.

             Those who held that there was an infinite plurality of principles had a diversity of opinions. For Democritus held that indivisible bodies which are called atoms are the principles of all things. And he held that bodies of this sort were all of one genus according to nature, but that they differed according to figure and form, and that they not only differed but even had contrariety among themselves. For he held three contrarieties: one according to figure, which is between the curved and the straight, another according to order, which is the prior and the posterior, and another according to position, namely, before and behind, above and below, to the right and to the left. And so he held that from these bodies existing of one nature different things come to be according to the diversity of the figure, position and order of the atoms. In this opinion, then, he gives us some basis for understanding the opposing opinion, namely that of Anaxagoras who held that the principles were infinite, but not of one genus according to nature. For he held that the principles of nature were the infinite, smallest parts of flesh and bone and other such things, as will be made clear below.

             It must be noted, however, that he did not divide these many principles into mobile and immobile. For none of these who held that the first principles were many held that they were immobile. For since all place contrariety in the principles, and since it is natural for contraries to change, immobility could not stand with a plurality of principles.

             14. Secondly, at the point where he says, 'A similar inquiry is made . . .' (184 b 23), he shows that there is the same diversity of opinions concerning beings.

             He says that in like manner the physicists, when inquiring about those things which are, i.e., about beings, wondered how many there are, i.e., whether there is one or many; and if many, whether finite or infinite.

             And the reason for this is that the ancient physicists did not know any cause but the material cause (although they touched lightly upon the other causes). Rather they held that the natural forms were accidents, as the forms of artificial things are. Since, therefore, the whole substance of artificial things is their matter, so it followed, according to them, that the whole substance of natural things would be their matter.

             Hence those who held one principle only, for example, air, thought that other beings were air according to their substance. And the same is true of the other opinions. Hence Aristotle says that the physicists seek what is in that from which things are, i.e., in inquiring about principles they sought the material causes from which beings are said to be. Whence it is clear that when they inquire about beings, whether they are one or many, their inquiry concerns the material principles which are called elements.

             15. Next where he says, 'Now to investigate . . .' (184 b 25), he shows that it does not pertain to natural science to disprove some of these opinions.

             And concerning this he makes two points. First he shows that it does not pertain to natural science to disprove the opinion of Parmenides and Melissus. Secondly, where he says, 'At the same time the holders of the theory . . .' (185 a 18), he gives a reason why it is useful to the present work to disprove this opinion.

             Concerning the first part he makes two points. First he shows that it does not pertain to natural science to disprove the aforesaid opinion. Secondly, where he says, '. . . or like refuting . . .' (185 a 8), he shows that it does not pertain to natural science to resolve the arguments which are brought forth to prove this opinion.

             He establishes his first point with two arguments, the second of which begins where he says, 'To inquire therefore . . .' (185 a 5).

             He says, therefore, that it does not pertain to natural science to undertake a thorough consideration of the opinion whether being is one and immobile. For it has already been shown that there is no difference, according to the intention of the ancient philosophers, whether we hold one immobile principle or one immobile being.

             And that it should not pertain to natural science to disprove this opinion he shows as follows. It does not pertain to geometry to bring forth reasons against an argument which destroys its principles. Rather, this either pertains to some other particular science (if, indeed, geometry is subalternated to some particular science, such as music is subalternated to arithmetic, to which it pertains to dispute against any position denying the principles of music), or it pertains to a common science such as logic or metaphysics. But the aforesaid position destroys the principles of nature. For if there is only one being, and if this being is immobile, such that from it others cannot come to be, then the very nature of a principle is taken away. For every principle is either a principle of some thing or of some things. Therefore, if we posit a principle, a multiplicity follows, because one is the principle and the other is that of which it is the principle. Whoever, therefore, denies multiplicity removes principles. Therefore natural science ought not to argue against this position.

             16. Next where he says, 'To inquire therefore . . .' (185 a 5), he shows the same point with another argument. It is not required of any science that it bring forth arguments against manifestly false and improbable opinions. For to worry about one who offers positions contrary to the opinions of the wise is stupid, as is said in Topics, I.

             He says, therefore, that to undertake a thorough consideration of the question whether being is one, and hence immobile, is like arguing against any other improbable position. For example, it is like arguing against the position of Heraclitus, who said that all things are always moved and that nothing is true; or against the position of one who would say that the whole of being is one man, which position, indeed, would be altogether improbable. And indeed whoever holds being to be only one immobile thing is forced to hold that the whole of being is some one thing. It is clear, therefore, that it does not belong to natural science to argue against this position.

             17. Next when he says, '. . . or like refuting . . .' (185 a 8), he shows that it does not belong to natural science even to resolve the arguments of the aforementioned philosophers. And this for two reasons, the second of which begins where he says, 'We physicists . . .' (185 a 13).

             First he proves his position by pointing out that it is not incumbent upon any science to resolve sophistic arguments which have an obvious defect of form or matter. He says that to deal with improbable arguments is like solving a contentious or sophistic argument. But each argument of both Melissus and Parmenides is sophistic, for they err in matter, whence he says that they have accepted what is false, i.e., they assume false propositions, and they err in form, whence he says that they are not syllogizing. But the position of Melissus is much worse, i.e., more vain and foolish and does not cause any difficulty. This will be shown below. Moreover, it is not inconsistent that given one inconsistency another should follow. Therefore it can be concluded that it is not required of the philosopher of nature that he resolve the arguments of this man.

             18. He sets forth the second argument for this where he says, 'We physicists . . .' (185 a 13). The argument is as follows. In natural science it is supposed that natural things are moved, either all or some of them. He says this because there is doubt whether some things are moved and how they are moved, for example, about the soul and the centre of the earth, and the pole of heaven, and about natural forms and other such things. But the fact that natural things are moved can be made clear from induction, for it is apparent to the sense that natural things are moved.

             It is as necessary that motion be supposed in natural science as it is necessary that nature be supposed. For motion is placed in the definition of nature, for nature is a principle of motion, as will be said below.

             Having established this point, that motion is supposed in natural science, he proceeds further to prove his position as follows. Not all arguments must be resolved in any science, but only those which conclude to something false from the principles of that science. Any arguments which do not reach their conclusions from the principles of the science, but from the contraries of these principles, are not resolved in that science. He proves this by an example taken from geometry saying that it pertains to geometry to resolve the problem of squaring, i.e., the squaring of a circle by dissecting the circumference, because this method supposes nothing contrary to the principles of the science of geometry. For somebody wished to find a square equal to a circle by dividing the circumference of the circle into many parts and placing straight lines in each part. And so by finding some figure, which was rectilinear, equal to some of the figures which were contained by the dissections of the circumference and the cords (either many or all), he thought he had found a rectilinear figure equal to the whole circle, to which it was easy to find an equal square through the principles of geometry. And thus he thought that he was able to find a square equal to a circle. But he did not argue well enough, for although these dissections used up the whole circumference of the circle, the figures contained by the dissections of the circumference and the straight lines did not encompass the whole circular surface.

             But to resolve the square of Antiphon does not pertain to geometry, because he used principles contrary to those of geometry. For he described in a circle a certain rectilinear figure, for example, a square. And he divided in half the arcs by which the sides of the square were subtended. And from the points of dissection he led straight lines to all the angles of the square. And then there resulted in the circle a figure of eight angles which more closely approached equality with the circle than the square. Then he again divided in half the arcs by which the sides of the octagon were subtended, and thus by leading straight lines from the points of dissection to the angles of this figure there resulted a figure of sixteen angles, which still further approached equality with the circle. Therefore, by always dividing the arcs and leading straight lines to the angles of the figure already existing there will arise a figure very near to equality with the circle. He said, then, that it was impossible to proceed to infinity in the dissection of arcs. Therefore, it was necessary to arrive at some rectilinear figure equal to the circle to which some square could be equal.

             But, because he supposed that an arc is not always divisible in half, which is contrary to the principles of geometry, it does not pertain to geometry to resolve an argument of this sort.

             Therefore, because the arguments of Parmenides and Melissus suppose being to be immobile (as will be shown below), and since this is contrary to the principles supposed in natural science, it follows that it does not pertain to the natural philosopher to resolve arguments of this sort.

             19. Next where he says, 'At the same time . . .' (185 a 18), he states why he will argue against the aforementioned position. He says that because the philosophers mentioned above did speak of natural things, even though they did not create a problem (that is, in the sphere of natural science), it is useful for his present purpose to argue against opinions of this sort. For even though it does not pertain to natural science to argue against such positions, it does pertain to first philosophy.