A critical history of Greek philosophy

by W. T. Stace

Let us apply these principles to the theory of Ideas. The absolute reality, the world of Ideas, is many, since [{198}] there are many Ideas, but it is one, because the Ideas are not isolated units, but members of a single organized system. There is, in fact, a hierarchy of Ideas. Just as the one Idea presides over many individual things of which it is the common element, so one higher Idea presides over many lower Ideas, and is the common element in them. And over this higher Idea, together with many others, a still higher Idea will rule. For example, the Ideas of whiteness, redness, blueness, are all subsumed under the one Idea of colour. The Ideas of sweetness and bitterness come under the one Idea of taste. But the Ideas of colour and taste themselves stand under the still higher Idea of quality. In this way, the Ideas form, as it were, a pyramid, and to this pyramid there must be an apex. There must be one highest Idea, which is supreme over all the others. This Idea will be the one final and absolutely real Being which is the ultimate ground, of itself, of the other Ideas, and of the entire universe. This Idea is, Plato tells us, the Idea of the Good. We have seen that the world of Ideas is many, and we now see that it is one. For it is one single system culminating in one supreme Idea, which is the highest expression of its unity. Moreover, each separate Idea is, in the same way, a many in one. It is one in regard to itself. That is to say, if we ignore its relations to other Ideas, it is, in itself, single. But as it has also many relations to other Ideas, it is, in this way, a multiplicity.

Every Idea is likewise a Being which contains not-being. For each Idea combines with some Ideas and not with others. Thus the Idea of corporeal body combines both with the Idea of rest and that of motion. [{199}] But the Ideas of rest and motion will not combine with each other. The Idea of rest, therefore, is Being in regard to itself, not-being in regard to the Idea of motion, for the being of rest is the not-being of motion. All Ideas are Being in regard to themselves, and not-being in regard to all those other Ideas with which they do not combine.

In this way there arises a science of Ideas which is called dialectic. This word is sometimes used as identical with the phrase, "theory of Ideas." But it is also used, in a narrower sense, to mean the science which has to do with the knowledge of which Ideas will combine and which not. Dialectic is the correct joining and disjoining of Ideas. It is the knowledge of the relations of all the Ideas to each other.

The attainment of this knowledge is, in Plato's opinion, the chief problem of philosophy. To know all the Ideas, each in itself and in its relations to other Ideas, is the supreme task. This involves two steps. The first is the formation of concepts. Its object is to know each Idea separately, and its procedure is by inductive reason to find the common element in which the many individual objects participate. The second step consists in the knowledge of the inter-relation of Ideas, and involves the two processes of classification and division. Classification and division both have for their object to arrange the lower Ideas under the proper higher Ideas, but they do this in opposite ways. One may begin with the lower Ideas, such as redness, whiteness, etc., and range them under their higher Idea, that of colour. This is classification. Or one may begin with the higher Idea, colour, and divide it into the lower Ideas, red, white, [{200}] etc. Classification proceeds from below upwards. Division proceeds from above downwards. Most of the examples of division which Plato gives are divisions by dichotomy. We may either divide colour straight away into red, blue, white, etc.; or we may divide each class into two sub-classes. Thus colour will be divided into red and not-red, not-red into white and not-white, not-white into blue and not-blue, and so on. This latter process is division by dichotomy, and Plato prefers it because, though it is tedious, it is very exhaustive and systematic.

Plato's actual performance of the supreme task of dialectic, the classification and arrangement of all Ideas, is not great. He has made no attempt to complete it. All he has done is to give us numerous examples. And this is, in reality, all that can be expected, for the number of Ideas is obviously infinite, and therefore the task of arranging them cannot be completed. There is, however, one important defect in the dialectic, which Plato ought certainly to have remedied. The supreme Idea, he tells us, is the Good. This, as being the ultimate reality, is the ground of all other Ideas. Plato ought therefore to have derived all other Ideas from it, but this he has not done. He merely asserts, in a more or less dogmatic way, that the Idea of the Good is the highest, but does nothing to connect it with the other Ideas. It is easy to see, however, why he made this assertion. It is, in fact, a necessary logical outcome of his system. For every Idea is perfection in its kind. All the Ideas have perfection in common. And just as the one beauty is the Idea which presides over all beautiful things, so the one perfection must be the supreme Idea which presides [{201}] over all the perfect Ideas. The supreme Idea, therefore, must be perfection itself, that is to say, the Idea of the Good. On the other hand it might, with equal force, be argued that since all the Ideas are substances, therefore the highest Idea is the Idea of substance. All that can be said is that Plato has left these matters in obscurity, and has merely asserted that the highest Idea is the Good.

Consideration of the Idea of the Good leads us naturally to enquire how far Plato's system is teleological in character. A little consideration will show that it is out and out teleological. We can see this both by studying the many lower Ideas, and the one supreme Idea. Each Idea is perfection of its kind. And each Idea is the ground of the existence of the individual objects which come under it. Thus the explanation of white objects is the perfect whiteness, of beautiful objects the perfect beauty. Or we may take as our example the Idea of the State which Plato describes in the "Republic." The ordinary view is that Plato was describing a State which was the invention of his own fancy, and is therefore to be regarded as entirely unreal. This is completely to misunderstand Plato. So far was he from thinking the ideal State unreal, that he regarded it, on the contrary, as the only real State. All existent States, such as the Athenian or the Spartan, are unreal in so far as they differ from the ideal State. And moreover, this one reality, the ideal State, is the ground of the existence of all actual States. They owe their existence to its reality. Their existence can only be explained by it. Now since the ideal State is not yet reached in fact, but is the perfect State towards which all actual States tend, it is clear that we have here [{202}] a teleological principle. The real explanation of the State is not to be found in its beginnings in history, in an original contract, or in biological necessities, but in its end, the final or perfect State. Or, if we prefer to put it so; the true beginning is the end. The end must be in the beginning, potentially and ideally, otherwise it could never begin: It is the same with all other things. Man is explained by the ideal man, the perfect man; white things by the perfect whiteness, and so on. Everything is explained by its end, and not by its beginning. Things are not explained by mechanical causes, but by reasons.

And the teleology of Plato culminates in the Idea of the Good. That Idea is the final explanation of all other Ideas, and of the entire universe. And to place the final ground of all things in perfection itself means that the universe arises out of that perfect end towards which all things move.

Another matter which requires elucidation here is the place which the conception of God holds in Plato's system. He frequently uses the word God both in the singular and the plural, and seems to slip with remarkable ease from the monotheistic to the polytheistic manner of speaking. In addition to the many gods, we have frequent reference to the one supreme Creator, controller, and ruler of the world, who is further conceived as a Being providentially watching over the lives of men. But in what relation does this supreme God stand to the Ideas, and especially to the Idea of the Good? If God is separate from the highest Idea, then, as Zeller points out, [Footnote 13] only three relations are possible, all of which are [{203}] equally objectionable. Firstly, God may be the cause or ground of the Idea of the Good. But this destroys the substantiality of the Idea, and indeed, destroys Plato's whole system. The very essence of his philosophy is that the Idea is the ultimate reality, which is self-existent, and owes its being to nothing else. But this theory makes it a mere creature of God, dependent on Him for its existence. Secondly, God may owe His being to the Idea. The Idea may be the ground of God's existence as it is the ground of all else in the universe. But this theory does violence to the idea of God, turning Him into a mere derivative existence, and, in fact, into an appearance. Thirdly, God and the Idea may be co-ordinate in the system as equally primordial independent ultimate realities. But this means that Plato has given two mutually inconsistent accounts of the ultimate reality, or, if not, that his system is a hopeless dualism. As none of these theories can be maintained, it must be supposed that God is identical with the Idea of the Good, and we find certain expressions in the "Philebus" which seem clearly to assert this. But in that case God is not a personal God at all, since the Idea is not a person. The word God, if used in this way, is merely a figurative term for the Idea. And this is the most probable theory, if we reflect that there is in fact no room for a personal God in a system which places all reality in the Idea, and that to introduce such a conception threatens to break up the whole system. Plato probably found it useful to take the popular conceptions about the personality of God or the gods and use them, in mythical fashion, to express his Ideas. Those parts of Plato which speak of God, and the governance of God, [{204}] are to be interpreted on the same principles as the other Platonic myths.

[Footnote 13: Plato and the Older Academy, chap. vi.]

Before closing our discussion of dialectic, it may be well to consider what place it occupies in the life of man, and what importance is attached to it. Here Plato's answer is emphatic. Dialectic is the crown of knowledge, and knowledge is the crown of life. All other spiritual activities have value only in so far as they lead up to the knowledge of the Idea. All other subjects of intellectual study are merely preparatory to the study of philosophy. The special sciences have no value in themselves, but they have value inasmuch as their definitions and classifications form a preparation for the knowledge of Ideas. Mathematics is important because it is a stepping-stone from the world of sense to the Ideas. Its objects, namely, numbers and geometrical figures, resemble the Ideas in so far as they are immutable, and they resemble sense-objects in so far as they are in space or time. In the educational curriculum of Plato, philosophy comes last. Not everyone may study it. And none may study it till he has been through all the preparatory stages of education, which form a rigorous discipline of the mind before it finally enters upon dialectic. Thus all knowledge ends in dialectic, and that life has not attained its end which falls short of philosophy.