A Critical History of Greek Philosophy, W. T. Stace [best books to read for students txt] 📗

id="id_209">{209} features of matter, as we know it, are due to the operation of the Ideas. Hence matter as it is in itself, before the image of the Ideas is stamped upon it, must be absolutely without quality, featureless, formless. But to be absolutely without any quality is to be simply nothing at all. This matter is, therefore, as Plato says, absolute not-being. Zeller conjectures, probably rightly, that what Plato meant was simply empty space. [Footnote 14] Empty space is an existent not-being, and it is totally indeterminate and formless. It accords with this view that Plato adopted the Pythagorean tenet that the differential qualities of material substances are due to their smallest particles being regular geometrical figures limited out of the unlimited, that is, out of space. Thus earth is composed of cubes. That is to say, empty space when bound into cubes (the limiting of the unlimited) becomes earth. The smallest particles of fire are tetrahedra, of air octahedra, of water icosahedra.

[Footnote 14: Plato and the Older Academy, chap. vii. ]

We have, then, on the one hand, the world of Ideas, on the other, matter, an absolutely formless, chaotic, mass. By impressing the images of the Ideas upon this mass, "things" arise, that is to say, the specific objects of sense. They thus participate both in Being and in not-being. But how is this mixing of Being and not-being brought about? How do the Ideas come to have their images stamped upon matter? It is at this point that we enter upon the region of myth. Up to this point Plato is certainly to be taken literally. He of course believed in the reality of the world of Ideas, and he no doubt also believed in his principle of matter. And he thought that the objects of sense are to be {210} explained as copies of the Ideas impressed upon matter. But now, with the problem how this copying is brought about, Plato leaves the method of scientific explanation behind. If the Ideas are the absolute ground of all things, then the copying process must be done by the Ideas themselves. They must themselves be made the principles for the production of things. But this is, for Plato, impossible. For production involves change. If the Ideas produce things out of themselves, the Ideas must in the process undergo change. But Plato has declared them to be absolutely unchangeable, and to be thus immutable is to be sterile. Hence the Ideas have within themselves no principle for the production of things, and the scientific explanation of things by this means becomes impossible. Hence there is nothing for it but to have recourse to myth. Plato can only imagine that things are produced by a world-former, or designer, who, like a human artist, fashions the plastic matter into images of the Ideas.

God, the Creator, the world-designer, finds beside him, on the one hand, the Ideas, on the other, formless matter. First, he creates the World-Soul. This is incorporeal, but occupies space. He spreads it out like a huge net in empty space. He bisects it, and bends the two halves into an inner and an outer circle, these circles being destined to become the spheres of the planets and the stars respectively. He takes matter and binds it into the four elements, and these elements he builds into the empty framework of the World-Soul. When this is done, the creation of the universe is complete. The rest of the "Timaeus" is occupied with the details of Plato's ideas of astronomy and physical {211} science. These are mostly worthless and tedious, and we need not pursue them here. But we may mention that Plato, of course, regarded the earth as the centre of the world. The stars, which are divine beings, revolve around it. They necessarily move in circles, because the circle is the perfect figure. The stars, being divine, are governed solely by reason, and their movement must therefore be circular, because a circular motion is the motion of reason.

The above account of the origin of the world is merely myth, and Plato knows that it is myth. What he apparently did believe in, however, was the existence of the World-Soul, and a few words upon this subject are necessary. The soul, in Plato's system, is the mediator between the world of Ideas and the world of sense. Like the former, it is incorporeal and immortal. Like the latter, it occupies space. Plato thought that there must be a soul in the world to account for the rational behaviour of things, and to explain motion. The reason which governs and directs the world dwells in the World-Soul. And the World-Soul is the cause of motion in the outer universe, just as the human soul is the cause of the motions of the human body. The cosmos is a living being.

(b) The Doctrine of the Human Soul.

The human soul is similar in kind to the World-Soul. It is the cause of the body's movements, and in it the human reason dwells. It has affinities both with the world of Ideas and the world of sense. It is divided into two parts, of which one part is again subdivided into two. The highest part is reason, which is {212} that part of the soul which apprehends the Ideas. It is simple and indivisible. Now all destruction of things means the sundering of their parts. But the rational part of the soul, being simple, has no parts. Therefore it is indestructible and immortal. The irrational part of the soul is mortal, and is subdivided into a noble and an ignoble half. To the noble half belong courage, love of honour, and in general the nobler emotions. To the ignoble portion belong the sensuous appetites. The noble half has a certain affinity with reason, in that it has an instinct for what is noble and great. Nevertheless, this is mere instinct, and is not rational. The seat of reason is the head, of the noble half of the lower soul, the breast, of the ignoble half, the lower part of the body. Man alone possesses the three parts of the soul. Animals possess the two lower parts, plants only the appetitive soul. What distinguishes man from the lower orders of creation is thus that he alone possesses reason.

Plato connects the doctrine of the immortality of the rational soul with the theory of Ideas by means of the doctrines of recollection and transmigration. According to the former doctrine, all knowledge is recollection of what was experienced by the soul in its disembodied state before birth. It must carefully be noted, however, that the word knowledge is here used in the special and restricted sense of Plato. Not everything that we should call knowledge is recollection. The sensuous element in my perception that this paper is white is not recollection, since, as being merely sensuous, it is not, in Plato's opinion, to be called knowledge. Here, as elsewhere, he confines the term {213} to rational knowledge, that is to say, knowledge of the Ideas, though it is doubtful whether he is wholly consistent with himself in the matter, especially in regard to mathematical knowledge. It must also be noted that this doctrine has nothing in common with the Oriental doctrine of the memory of our past lives upon the earth. An example of this is found in the Buddhist Jàtakas, where the Buddha relates from memory many things that happened to him in the body in his previous births. Plato's doctrine is quite different. It refers only to recollection of the experiences of the soul in its disembodied state in the world of Ideas.

The reasons assigned by Plato for believing in this doctrine may be reduced to two. Firstly, knowledge of the Ideas cannot be derived from the senses, because the Idea is never pure in its sensuous manifestation, but always mixed. The one beauty, for example, is only found in experience mixed with the ugly. The second reason is more striking. And, if the doctrine of recollection is itself fantastic, this, the chief reason upon which Plato bases it, is interesting and important. He pointed out that mathematical knowledge seems to be innate in the mind. It is neither imparted to us by instruction, nor is it gained from experience. Plato, in fact, came within an ace of discovering what, in modern times, is called the distinction between necessary and contingent knowledge, a distinction which was made by Kant the basis of most far-reaching developments in philosophy. The character of necessity attaches to rational knowledge, but not to sensuous. To explain this distinction, we may take as our example of rational knowledge such a proposition as that two {214} and two make four. This does not mean merely that, as a matter of fact, every two objects and every other two objects, with which we have tried the experiment, make four. It is not merely a fact, it is a necessity. It is not merely that two and two do make four, but that they must make four. It is inconceivable that they should not. We have not got to go and see whether, in each new case, they do so. We know beforehand that they will, because they must. It is quite otherwise with such a proposition as, "gold is yellow." There is no necessity about it. It is merely a fact. For all anybody can see to the contrary it might just as well be blue. There is nothing inconceivable about its being blue, as there is about two and two making five. Of course, that gold is yellow is no doubt a mechanical necessity, that is, it is determined by causes, and in that sense could not be otherwise. But it is not a logical necessity. It is not a logical contradiction to imagine blue gold, as it would be to imagine two and two making five. Any other proposition in mathematics possesses the same necessity. That the angles at the base of an isosceles triangle are equal is a necessary proposition. It could not be otherwise without contradiction. Its opposite is unthinkable. But that Socrates is standing is not a necessary truth. He might just as well be sitting.

Since a mathematical proposition is necessarily true, its truth is known without verification by experience. Having proved the proposition about the isosceles triangle, we do not go about measuring the angles of triangular objects to make sure there is no exception. We know it without any experience at all. And if we {215} were sufficiently clever, we might even evolve mathematical knowledge out of the resources of our own minds, without its being told us by any teacher. That Caesar was stabbed by Brutus is a fact which no amount of cleverness could ever reveal to me. This information I can only get by being told it. But that the base angles of an isosceles triangle are equal I could discover by merely thinking about it. The proposition about Brutus is not a necessary proposition. It might be otherwise. And therefore I must be told whether it is true or not. But the proposition about the isosceles triangle is necessary, and therefore I can see that it must be true without being told.

Now Plato did not clearly make this distinction between necessary and non-necessary knowledge. But what he did perceive was that mathematical knowledge can be known without either experience or instruction. Kant afterwards gave a less fantastic explanation of these facts. But Plato concluded that such knowledge must be already present in the mind at birth. It must be recollected from a previous existence. It might be answered that, though this kind of knowledge is not gained from the experience of the senses, it may be gained from teaching. It may be imparted by another mind. We have to teach children mathematics, which we should not have to do if it were already in