A Critical History of Greek Philosophy Part 13

In 347 B.C. Plato died, and his nephew Speusippus was chosen as head of the Academy. Aristotle left Athens with his fellow-student Xenocrates, and together they repaired to the court of Hermeias, King of Atarneus, in Asia Minor. Hermeias, a man of low origin, but of high instincts and advanced education, had himself attended the lectures of Plato, and received the two young philosophers as welcome guests.

Aristotle stayed three years at Atarneus, and, while there, married {251} Pythias, the niece of the King. In later life he was married a second time to one Herpyllis, who bore him a son, Nichomachus. At the end of three years Hermeias fell a victim to the treachery of the Persians, and Aristotle went to Mytilene. Here he remained for several years till he received an invitation from Philip of Macedonia to become the tutor of the young Alexander, afterwards conqueror of the world, then aged thirteen. Aristotle obeyed the summons, and for about five years superintended the education of Alexander. Both Philip and Alexander appear to have paid Aristotle high honour, and there were stories that he was supplied by the Macedonian court, not only with funds for the prosecution of learning, but even with thousands of slaves for the collection of specimens. These stories are probably false and certainly exaggerated. But there is no doubt that, in his scientific and philosophical enquiries, he was backed by the influence of the court, and could even perhaps have looked to that quarter for supplies, had it ever been necessary.

Upon the death of Philip, Alexander succeeded to the kingship. The period of his studies was now over, and he began to make preparations for his subsequent conquests. Aristotle's work being finished, he returned to Athens, which he had not visited since the death of Plato.

He found the Platonic school flourishing under Xenocrates, and Platonism the dominant philosophy of Athens. He thereupon set up his own school at a place called the Lyceum. It was in connection with this that his followers became known, in after years, as the "peripatetics," a name which arose from Aristotle's habit of walking about as he discoursed. The period of {252} his residence in Athens lasted thirteen years, during which time he was occupied in the leadership of his school and in literary labours. This appears to have been the most fruitful period of his life. There is no doubt that all his most important writings were composed at this time. But at the end of this period his fortunes changed.

In B.C. 323 Alexander the Great died suddenly at Babylon in the midst of his triumphs. The Athenian Government was in the hands of a pro-Macedonian party. Upon the death of Alexander this party was overthrown, and a general reaction occurred against everything Macedonian. Alexander had been regarded in Greece much as Napoleon was regarded in Europe a century ago. He had insulted the free Greek cities. He had even sacked the city of Thebes. The whole of Greece lived in perpetual terror of invasion. Now that this fear was removed by his death, there was a general outburst of feeling against Macedonia. An anti-Macedonian party came into power. Now Aristotle had always been regarded as a representative and protege of the Macedonian court, although, as a matter of fact, he had recently fallen out of favour with the autocratic Alexander. A charge of impiety was trumped up against him. To escape prosecution he fled to Chalcis in Euboea, in order that, as he said, "the Athenians might not have another opportunity of sinning against philosophy as they had already done in the person of Socrates." He perhaps intended to return to Athens as soon as the storm had blown over. But in the first year of his residence at Chalcis he was overtaken by a sudden illness, and died at the age of sixty-three, in B.C. 322.

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Aristotle is said to have composed some four hundred books. Our astonishment at this productivity diminishes somewhat when we remember that what is here called a "book" is much the same as what we should call a chapter in a modern treatise. More than three-quarters of these writings have been lost. But, by good fortune, what remains to us is undoubtedly by far the most important part, and we have preserved in it a fairly complete account of the whole Aristotelian system in all its departments. Nearly all the writings, however, have come down to us in a mutilated state. This is especially the case with the "Metaphysics." This treatise is unfinished, and it was probably left unfinished by its author at his death. But apart from this, several of the books of the "Metaphysics" are undoubtedly spurious. Others apparently come in the wrong order. We end one book in the middle of a discussion, and when we begin the next we find ourselves in the middle of an entirely different subject. There are frequent repet.i.tions, and parts of it read as if they were mere lecture notes. There are many interpolations. The same characteristics are to be observed in Aristotle's other writings, though in a less degree. It seems probable that they were not intended, in their present state, for publication.

Final revision and finishing touches are lacking. In spite of these defects, the writings are voluminous and clear enough to enable us to trace out the whole of the main positions of Aristotle's thought.

We saw, in the case of Plato, that, as his literary activity lasted over a period of half a century, during which his philosophy was in constant development, it became important to trace this development in the {254} order of his Dialogues. The same thing is not true in the case of Aristotle. The whole of his writings, or rather those that have come down to us, seem to have been written during his last thirteen years, while he was at Athens, that is to say, after he had pa.s.sed his fiftieth year. His system was then complete, mature, and fully developed. The question of the order in which they were written has no great importance. The result of critical investigations, however, is to show that he probably began with the various works upon logic, composed next the treatises upon physical science, next the ethical and political books, and lastly the "Metaphysics," which he left unfinished.

It must not be forgotten that Aristotle was not only a philosopher in the modern restricted sense of that term. He was a man of universal learning. There is no branch of knowledge which did not receive his attention, and upon which he was not the greatest expert of his time, except perhaps mathematics. So far was he from being only an abstract philosopher, that his natural tastes seem to have lain rather in the field of physical science than of abstract thought. But his design seems to have been to work over the entire field of knowledge, thoroughly to overhaul the sciences already in existence, rejecting what seemed false in the work of his predecessors, and invariably adding to the residue valuable developments and suggestions of his own. Where there was no science already in existence, his plan involved the foundation of new sciences wherever necessary, and he thus became the founder of at least two sciences, Logic and Zoology.

He thus attained to a pre-eminence in all branches {255} of knowledge which would be impossible for a single man in modern times. His works include treatises upon Logic and Metaphysics, upon Ethics, Politics, and Art. He wrote a treatise upon the principles of Rhetoric, another upon Astronomy, under the t.i.tle "On the Heavens," another upon Meteorology. Several of his treatises deal with the biology of animal life, in which he was intensely interested. They include books ent.i.tled "On the Parts of Animals," "On the Movements of Animals," "On the Origin of Animals," as well as his great treatise, "Researches on Animals," which contains an enormous ma.s.s of facts collected from every possible source. It is true that a large proportion of these facts have turned out to be fictions, but this was inevitable in the infancy of science. It has been calculated that Aristotle shows himself acquainted with about five hundred different species of living beings, though they are not, of course, cla.s.sified by him in the modern way. With these books upon animals he founded the science of Zoology, for no one before his day had made any special study of the subject.

It has been said that everyone has either an Aristotelian or a Platonic type of mind. As this implies that Aristotle and Plato are opposites, it is considerably less than a half truth. No genuine understanding of Aristotle can endorse the opinion that his philosophical system was the opposite of Plato's. It would be truer to say that Aristotle was the greatest of all Platonists, since his system is still founded upon the Idea, and is an attempt to found an idealism free from the defects of Plato's system. It is in fact a development of Platonism. What is the cause then of the popular notion that {256} Aristotle was the opposite of Plato? Now the fact is that they _were_ opposites in many important respects. But there was a fundamental agreement between them which lies deeper than the differences. The differences are largely superficial, the agreement is deep-seated. Hence it is the differences that are most obvious, and it was the differences, too, which were most obvious to Aristotle himself. The popular opinion arises largely from the fact that Aristotle never loses an opportunity of attacking the Platonic theory of Ideas. He is continually at pains to emphasize the difference between himself and Plato, but says nothing of the agreement. But no man is a judge of his own deeper relations to his predecessors and contemporaries. It is only in after years, when the hubbub of controversy has settled down into the silence of the past, that the historian can see the true perspective, and can penetrate the relations of each great man to the time in which he lived. Plato was the founder of idealism, and his idealism was in many respects crude and untenable. It was the special mission of Aristotle to clear away these crudities, and so develop Platonism into a tenable philosophy.

And it was natural that he should emphasize the crudities, which he had to fight so hard to overcome, rather than that substratum of truth which Plato had already developed, and which therefore required no special treatment at his hands. It was the differences between himself and his predecessor which were most obvious to him, and it was inevitable that he should adopt a thoroughly polemical att.i.tude towards his master.

But if the agreement was more deep-seated than the differences, and lay in the recognition of the Idea as the {257} absolute foundation of the world, the differences were none the less very striking. In the first place, Aristotle loved facts. What he wanted was always definite scientific knowledge. Plato, on the other hand, had no love of facts and no gift for physical enquiries. And what disgusted Aristotle about the system of Plato was the contempt which it poured upon the world of sense. To depreciate objects of sense, and to proclaim the knowledge of them valueless, was a fundamental characteristic of all Plato's thinking. But the world of sense is the world of facts, and Aristotle was deeply interested in facts. No matter in what branch of knowledge, any fact was received by Aristotle with enthusiasm. To Plato it appeared of no interest what the habits of some obscure animal might be. That alone which should be pursued is the knowledge of the Idea.

And he went so far as to deny that knowledge of the sense-world could properly be described as knowledge at all. But the habits of animals appeared to Aristotle a matter worthy of investigation for its own sake. Francis Bacon in his "Novum Organum" has many contemptuous references to Aristotle. And the gist of them all is that Aristotle had no regard for facts, but theorized a priori out of his head, and that instead of patiently investigating the facts of nature, he decided, upon so-called "rational" grounds, what nature ought to do, and squared the facts with his theories.

It was natural for Bacon to be unjust to him. He, with the other thinkers of his time, was engaged upon an uphill fight against scholasticism, then dominant, which claimed to represent the true teaching of Aristotle. And it was true that the schoolmen theorized a priori, {258} and ignored facts, or, what was worse, appealed to the writings of Aristotle to decide questions of fact which should have been decided by an appeal to nature. And Bacon not unnaturally confounded Aristotle with these modern Aristotelians, and attributed to him the faults that were really theirs. But no man was ever keener on facts than Aristotle as is proved by his treatises upon animals, which contain evidences of astonishing patience and laborious work in the collection of facts. It is true, however, that even in the domain of facts, Aristotle, like all the ancients, was guilty of introducing _a priori_ reasonings when they were quite out of place. Thus he does not scruple to argue that the stars must move in circles because the circle is the perfect figure. And numerous similar instances could be quoted. But it was inevitable that, with science in its swaddling clothes, without the aid of any instruments, or of any body of previously ascertained truths, Aristotle should fall into these snares. He well understood the fundamental necessity of all natural sciences for a laborious investigation of facts, but, when this was impossible, he used the only means in his power, his reason.

Secondly, in spite of Plato's rationalism, he had allowed to myths and poetry a large share in the development of his thoughts, and had even exhibited a distinct tendency towards mysticism. Here again what Aristotle wanted was definite knowledge. It pained him to see poetic metaphors subst.i.tuted for rational explanation. And this accounts for the third main difference between Plato and Aristotle, the marked contrast in their prose styles. Plato was a master-artist in words.

Aristotle cared nothing for the ornaments and beauties of style. {259} He harshly excludes them from his work. What alone he is intent upon is the meaning, the truth that the words express. He is too much in earnest with philosophy to lose himself in a haze of beautiful words, or to be put off with metaphors instead of reasons. His style is even harsh, abrupt, and ugly. But what it loses in beauty it gains in clearness of conception. For every thought or shade of thought which it is desired to express there is an accurate term. If no term in common use will express the thought, Aristotle coins one. Hence he is one of the greatest terminologists that ever lived. He adapted or invented an enormous number of terms. He may be not unjustly regarded as the founder of philosophical language, as the inventor of a vocabulary of technical terms. Many of the terms used to this day to express man's most abstract thoughts, were invented or introduced by Aristotle. It must not be supposed that Aristotle wrote in a rigidly scientific style because he had no aesthetic sense. The very contrary is the case. His treatise on art shows him by far the best critic of the ancient world, and in his appreciation and estimation of the beautiful he far excels Plato. But he saw that art and science have each their own sphere, and that it is fatal to confuse the two.

Nothing is so damaging to art as to be made the mere vehicle of reasoning. Nothing is so damaging to philosophy as to allow itself to be governed by poetry. If we want beauty, we must follow the path of art. But if we desire truth, we must stick close to reason.

Aristotle's system falls most easily into the fivefold division of logic, metaphysics, physics, ethics, and aesthetics.

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2. Logic.

Not much need be said under this head, because whoever knows the common logic of the text-books knows the logic of Aristotle. Of the two branches of reasoning, deductive and inductive, Aristotle clearly recognizes the latter. And many of his observations upon induction are acute and penetrating. But he has not reduced induction to a science.

He has not laid bare the fundamental canons of inductive thought. This was a work not performed until comparatively modern times. His name therefore is more especially a.s.sociated with deductive logic, of which he was the founder. He not only founded the science, but practically completed it. What we now know as "formal logic," what is to this day contained in all text-books, taught in all schools and universities, is, in all its essentials, nothing more than the logic of Aristotle.

His writings upon the subject include the treatment of the well-known laws of thought, the doctrine of the ten categories, the five predicables, the doctrines of terms, of propositions, of syllogisms, and of the reduction of the other figures to the first figure of the syllogism. And these heads might well form the list of contents of a modern work on formal logic. In only two respects has any advance been made upon Aristotle by subsequent logicians. The fourth figure of the syllogism is not recognized by Aristotle; and he dealt only with categorical syllogisms, and does not treat conditional syllogisms. But whether or not the fourth figure of the syllogism has any value is still a matter open to dispute. And though the doctrine of conditional syllogisms is important, it is not essential, because all conditional syllogisms can be reduced to categorical {261} syllogisms. The categorical syllogism is the fundamental type of reasoning, to which every other form of deduction can be reduced. As for the rest of the huge treatises on formal logic which some moderns have produced, the supposed additions are nothing but wearisome, endless, useless, nauseating, academic distinctions and refinements, which are much better forgotten than remembered. Aristotle's logic contains therefore all that is essential to the subject. The only ground on which it can be attacked is its wholly empirical procedure. But that is another story. As a collection, arrangement, and a.n.a.lysis of the facts of reason, it is to all intents and purposes finality achieved at one stroke.

3. Metaphysics.

The treatise now known as the "Metaphysics" of Aristotle did not originally bear that name. Aristotle's name for this subject is "first philosophy," by which he means the knowledge of the first, highest, or most general principles of the universe. All other branches of knowledge are subordinate to this science, not because they are inferior in value, but because they are lower in logical sequence as dealing with principles less universal in their scope. Thus all the special sciences deal with one or another particular sphere of being, but the "first philosophy" has for its subject being as such, "being so far forth as it is being." It studies, not the characteristics of this or that kind of being, but the principles which are equally true of all being. The laws of Zoology apply only to animals, but the principles of the "first philosophy" apply to everything. The name "metaphysics" came into use only half a century B.C., when {262} Andronicus published a complete edition of Aristotle's known works. In this edition the treatise on "first philosophy" was placed after the "physics," and "metaphysics" signifies simply "after physics." The derivation of the word thus appears to be merely accidental and advent.i.tious. Whether it was also in any way intended to signify that the subject is "beyond physics," that is, deals with what transcends physical existence, seems doubtful.

Aristotle's metaphysical theory grows naturally out of his polemic against Plato's theory of Ideas, because his own system was in effect simply an attempt to overcome the defects which he found in Plato. The main heads of this polemic are the following:--

(1) Plato's Ideas do not explain the existence of things. To explain why the world is here is after all the main problem of philosophy, and Plato's theory fails to do this. Even admitting that, say, the Idea of whiteness exists, we cannot see how it produces white objects.

(2) Plato has not explained the relation of Ideas to things. Things, we are told, are "copies" of Ideas, and "partic.i.p.ate" in them. But how are we to understand this "partic.i.p.ation"? In using such phrases, says Aristotle, Plato is giving no real account of the relationship, but is merely "uttering poetic metaphors."

(3) Even if the existence of things is explained by the Ideas, their motion is not. Suppose that the Idea of whiteness produces white things, the Idea of beauty beautiful things, and so on, yet, since the Ideas themselves are immutable and motionless, so will be the world which is their copy. Thus the universe would be {263} absolutely static, like Coleridge's "painted ship upon a painted ocean." But the world, on the contrary, is a world of change, motion, life, becoming.

Plato makes no attempt to explain the unceasing becoming of things.

Even if the Idea of whiteness explains white objects, yet why do these objects arise, develop, decay, and cease to exist? To explain this there must be some principle of motion in the Ideas themselves. But there is not. They are immovable and lifeless.

(4) The world consists of a mult.i.tude of things, and it is the business of philosophy to explain why they exist. By way of explanation Plato merely a.s.sumes the existence of another mult.i.tude of things, the Ideas. But the only effect of this is to double the number of things to be explained. How does it help thus to duplicate everything? And Aristotle likens Plato to a man who, being unable to count with a small number, fancies that, if he doubles the number, he will find it easier to count.

(5) The Ideas are supposed to be non-sensuous, but they are, in fact, sensuous. Plato thought that a non-sensuous principle must be sought in order to explain the world of sense. But not being able to find any such principle, he merely took the objects of sense over again and called them non-sensuous. But there is, in fact, no difference between the horse and the Idea of the horse, between the man and the Idea of the man, except a useless and meaningless "in-itself" or "in-general"

attached to each object of sense to make it appear something different. The Ideas are nothing but hypostatized things of sense, and Aristotle likens them to the anthropomorphic G.o.ds of the popular religion. "As {264} these," he says, "are nothing but deified men, so the Ideas are nothing but eternalized things of nature." Things are said to be copies of Ideas, but in fact the Ideas are only copies of things.

(6) Next comes the argument of the "third man," so called by Aristotle from the ill.u.s.tration by which he explained it. Ideas are a.s.sumed in order to explain what is common to many objects. Wherever there is a common element there must be an Idea. Thus there is a common element in all men, and therefore there is an Idea of man. But there is also an element common to the individual man and to the Idea of man. There must, therefore, be a further Idea, the "third man," to explain this.

And between this further Idea and the individual man there must be yet another Idea to explain what they have in common, and so on _ad infinitum_.

(7) But by far the most important of all Aristotle's objections to the ideal theory, and that which, to all intents and purposes, sums up all the others, is that it a.s.sumes that Ideas are the essences of things, and yet places those essences outside the things themselves. The essence of a thing must be in it, and not outside it. But Plato separated Ideas from things, and placed the Ideas away somewhere in a mysterious world of their own. The Idea, as the universal, can only exist in the particular. Possibly the reality in all horses is the universal horse, but the universal horse is not something that exists by itself and independently of individual horses. Hence Plato was led into the absurdity of talking as if, besides the individual horses we know, there is somewhere another individual called the horse-in-general, or as if besides white objects there is a thing called {265} whiteness. And this is in fact the supreme self-contradiction of the theory of Ideas, that it begins by saying that the universal is real, and the particular unreal, but ends by degrading the universal again into a particular. This is the same thing as saying that Plato's mistake lay in first (rightly) seeing that existence is not reality, but then (wrongly) going on to imagine that the reality is an existence.

Out of this last objection grows Aristotle's own philosophy, the fundamental principle of which is that the universal is indeed the absolute reality, but that it is a universal which exists only in the particular. What is reality? What is substance? This is the first question for the metaphysician. Now substance is what has an independent existence of its own; it is that whose being does not flow into it from any source outside itself. Consequently, substance is what is never a predicate; it is that to which all predicates are applied. Thus in the proposition, "Gold is heavy," gold is the subject, or substance, and "heavy" is its predicate. The heaviness is dependent for its existence on the gold, and it is therefore the latter, and not the former, that is the substance.

Now, keeping this in mind, are universals, as Plato a.s.serts, substances? No; because the universal is merely a common predicate which attaches to many objects of a cla.s.s. Thus the concept of man is merely what is common to all men. It is the same thing as the predicate "humanness." But humanness cannot exist apart from human beings, any more than heaviness apart from the heavy object.

Universals, then, are not substances. But neither are particulars substances. For there is no such thing as that which is absolutely {266} particular and isolated. If humanness does not exist apart from men, neither do men exist apart from humanness. Take away from a man what he has in common with other men, and what he has in common with other objects, and you will find that, having stripped him of all his qualities, there is absolutely nothing left. We say gold is heavy, yellow, malleable, etc. Now the heaviness, the yellowness, and the other qualities, cannot exist apart from the gold. But it is equally true that the gold cannot exist apart from its qualities. Strip off all its qualities in thought, and then ask yourself what the gold itself is apart from its qualities. You will find that your mind is a total blank. In taking away the qualities you have taken away the gold itself. The gold can only be thought through its qualities. It only exists through its qualities. The gold, therefore, just as much depends on the qualities for its existence as the qualities depend upon the gold. Hence neither of them, considered apart from the other, is substance. But the qualities are the universal element in the gold, the gold without the qualities is the absolutely particular and isolated. For, first, the yellowness is a quality which this gold has in common with that gold, and is therefore a universal, and so with all the qualities. Even if a particular piece of gold has a quality possessed by no other gold, it is yet possessed by some other object in the universe, or it would be unknowable. Every quality is consequently a universal. Secondly, the gold without its qualities is the absolutely particular. For, being stripped of all qualities, it is stripped of whatever it has in common with other things; it is stripped of whatever universality it has, and it remains an absolute particular. Hence the {267} universal is not substance, nor is the particular. For neither of them can exist without the other. Substance must be a compound of the two; it must be the universal in the particular. And this means that that alone which is substance is the individual object, for example, the gold with all its qualities attached to it.

It is usually believed that Aristotle contradicted himself in as much as he first states, as above, that the individual object, the compound of universal and particular, is substance, but later on allows a superior reality to the universal, or "form" as he calls it, and in effect teaches, like Plato, that the universal is what alone is absolutely real, that is, that the universal is substance. I do not agree that there is any real inconsistency in Aristotle. Or rather, the inconsistency is one of words and not of thought. It must be remembered that, whenever Aristotle says that the individual, and not the universal, is substance, he is thinking of Plato. What he means to deny is that the universal can exist on its own account, as Plato thought. Nevertheless he agrees with Plato that the universal is the real. When he says that the universal is not substance he means, as against Plato, that it is not existent. What alone exists is the individual thing, the compound of universal and particular. When he says, or implies, that the universal is substance, he means that, though it is not existent, it is real. His words are contradictory, but his meaning is not. He has not expressed himself as clearly as he should; that is all.

The further development of Aristotle's metaphysics depends upon his doctrine of causation. By causation here, however, is meant a very much wider conception {268} than what is understood by that term in modern times. I have in previous lectures attempted to make clear the distinction between causes and reasons. The cause of a thing does not give any reason for it, and therefore does not explain it. The cause is merely the mechanism by which a reason produces its consequence.

Death is caused by accident or disease, but these causes explain nothing as to why death should be in the world at all. Now if we accept this distinction, we may say that Aristotle's conception of causation includes both what we have called causes and reasons.

Whatever is necessary, whether facts or principles, whether causes or reasons, fully to understand the existence of a thing, or the happening of an event, is included in the Aristotelian notion of causation.

Taking causation in this wide sense, Aristotle finds that there are four kinds of causes, the material, the efficient, the formal, and the final cause. These are not alternative causes; it is not meant that, to explain anything, one or other of the four must be present. In every case of the existence or production of a thing all four causes operate simultaneously. Moreover the same four causes are to be found both in human and in cosmic production, in the making of manufactured articles by man and in the production of things by nature. They are more clearly and easily seen, however, in human production, from which sphere, therefore, we select our example. The material cause of a thing is the matter of which it is composed. It is the raw material which becomes the thing. For example, in the making of a bronze statue of Hermes, the bronze is the material cause of the statue. This example might lead one to suppose {269} that Aristotle means by material cause what we call matter, physical substance, such as bra.s.s, iron, or wood. As we shall see later, this is not necessarily the case, though it is so in the present instance. The efficient cause is always defined by Aristotle as the cause of motion. It is the energy or moving force required to bring about change. It must be remembered that by motion Aristotle means not merely change of place but change of any sort. The alteration of a leaf from green to yellow is just as much motion, in his sense, as the falling of a stone. The efficient cause, then, is the cause of all change. In the example taken, what causes the bronze to become a statue, what produces this change, is the sculptor. He is, therefore, the efficient cause of the statue. The formal cause Aristotle defines as the substance and essence of the thing. Now the essence of a thing is given in its definition. But the definition is the explication of the concept. Therefore the formal cause is the concept, or, as Plato would call it, the Idea of the thing. Plato's Ideas thus reappear in Aristotle as formal causes. The final cause is the end, purpose, or aim, towards which the movement is directed. When a statue is being produced, the end of this activity, what the sculptor aims at, is the completed statue itself. And the final cause of a thing in general is the thing itself, the completed being of the object.

We can see at once how much wider this conception of causation is than the modern conception. If we take Mill's definition of a cause as the best expression of modern scientific ideas, we find that he defines a cause as the "invariable and unconditional antecedent of a phenomenon." This cuts out final causes at once. For {270} the final cause is the end, and is not an antecedent in time. It also does not include formal causes. For we do not now think of the concept of a thing as being part of its cause. This leaves us with only material and efficient causes, and these correspond roughly to the modern notions of matter and energy. Even the efficient causes of Aristotle, however, appear on further consideration, to be excluded from the modern idea of causation. For, though the efficient cause is the energy which produces motion, modern science regards it as purely mechanical energy, whereas Aristotle thinks of it, as we shall see, as an ideal force, operating not from the beginning but from the end. But it must not be supposed that, in saying that the modern idea of causation excludes formal and final causes, we mean that Aristotle is wrong in adding them, or that the modern idea is better than Aristotle's. It is not a question of better and worse at all. Modern science does not in any way deny the reality of formal and final causes. It merely considers them to be outside its sphere. It is no business of science whether they exist or not. As knowledge advances, differentiation and division of labour occur. Science takes as its province mechanical causes, and leaves formal and final causes to the philosopher to explicate. Thus, for example, formal causes are not considered by science because they are not, in the modern sense, causes at all. They are what we have called reasons. If we are to explain the existence of an object in the universe it may be necessary to introduce formal causes, concepts, to show why the thing exists, to show in fact its reasons. But science makes no attempt to explain the existence of objects. It takes their {271} existence for granted, and seeks to trace their history and their relations to each other.

Therefore it does not require formal causes. It seeks to work out the mechanical view of the universe, and therefore considers only mechanical causes. But Aristotle's theory, as being philosophy rather than science, includes both the principles of mechanism and teleology.

It was not Aristotle's habit to propound his theories as if they were something absolutely new, sprung for the first time out of his own brain. In attacking any problem, his custom was to begin by enumerating current and past opinions, to criticise them, to reject what was valueless in them, to retain the residue of truth, and to add to it his own suggestions and original ideas. The resultant of this process was his own theory, which he thus represented, not as absolutely new, but as a development of the views of his predecessors.

This course he follows also in the present instance. The first book of the "Metaphysics" is a history of all previous philosophy, from Thales to Plato, undertaken with the object of investigating how far the four causes had been recognized by his predecessors. The material cause, he says, had been recognized from the first. The Ionics believed in this and no other cause. They sought to explain everything by matter, though they differed among themselves as to the nature of the material cause, Thales describing it as water, Anaximenes as air. Later philosophers also gave different accounts of it, Heracleitus thinking it was fire, Empedocles the four elements, Anaxagoras an indefinite number of kinds of matter. But the point is that they all recognized the necessity for a material cause of some sort to explain the universe.

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The earliest thinkers, then, the Ionics, a.s.sumed only this one cause.

But as thought advanced, says Aristotle, and other philosophers came upon the scene, "the thing itself guided them." It was seen that a second cause was necessary to explain the motion and becoming of things. For matter itself does not produce its motion. Wood is not the cause of its becoming a bed, nor is bra.s.s the cause of its becoming a statue. Hence arose the idea of the efficient cause. The Eleatics did not recognize it, for they denied motion, and for them, therefore, no cause of motion could be a.s.sumed. But Parmenides, Aristotle thinks, wavered on this point, somehow allowing vaguely the existence of a second cause, which he denominated the hot and the cold. The reference is, of course, to the second part of the poem of Parmenides. Other philosophers clearly a.s.sumed an efficient cause, for they thought that one element, for example, fire, is more active, that is, more productive of motion, than others. Empedocles certainly attained to the idea of an efficient cause, for he named as moving forces, harmony and discord, love and hate. Anaxagoras also, used Nous as a moving force.

Formal causes had, perhaps, been recognized by the Pythagoreans, for numbers are forms. But they straightway degraded the formal cause to the level of a material cause by declaring that number is the stuff or matter of which things are made. Plato alone clearly saw the necessity for the formal cause, for formal causes are, as we have seen, the same as Plato's Ideas. But Plato's philosophy contains only two of the four causes, namely the material and the formal, for Plato made all things out of matter and the Ideas. Since the Ideas have in them {273} no principle of motion, Plato's system contains no efficient cause. As for final causes, Plato had indeed the vague idea that everything is for the sake of the Good, but he makes no use of this conception and does not develop it. Final causes were introduced into philosophy by Anaxagoras, whose doctrine of the world forming mind was a.s.sumed to explain the design and purpose which the universe exhibits. But as his system developed he forgot about this, and used the Nous merely as a piece of mechanism to explain motion, thus letting it sink into nothing more than an efficient cause.

In the result, Aristotle finds that all four causes have been recognized in greater or lesser degrees by his predecessors, and this, in his opinion, greatly reinforces his own doctrine. But whereas material and efficient causes have been clearly understood, his predecessors had only vaguely foreshadowed and dimly perceived the value of formal and final causes.

The next step in Aristotle's metaphysics is to reduce these four principles to two, which he calls matter and form. This reduction takes place by showing that formal cause, efficient cause, and final cause, all melt into the single conception of form. In the first place, the formal cause and the final cause are the same. For the formal cause is the essence, the concept, the Idea, of the thing. Now the final cause, or the end, is simply the realisation of the Idea of the thing in actuality. What the thing aims at is the definite expression of its form. It thus aims at its form. Its end, final cause, is thus the same as its formal cause. Secondly, the efficient cause is the same as the final cause. For the efficient cause is the cause of becoming. The final cause is the end of {274} the becoming, it is what it becomes. And, in Aristotle's opinion, what causes the becoming is just that it aims at the end. The striving of all things is towards the end, and exists because of the end. The end is thus itself the cause of becoming or motion. That is to say, the final cause is the real efficient cause. We may see this better by an example. The end or final cause of the acorn is the oak. And it is the oak which is the cause of the acorn's growth, which consists essentially in a movement by which the acorn is drawn towards its end, the oak. We may see this even more definitely in the case of human productions, because here the striving towards an end is conscious, whereas in nature it is unconscious or instinctive. The efficient cause of the statue is the sculptor. It is he that moves the bra.s.s.

But what moves the sculptor, and causes him to act upon the bra.s.s, is the idea of the completed statue in his mind. The idea of the end, the final cause, is thus the real ultimate cause of the movement. Only, in the case of human production, the idea of the end is actually present in the sculptor's mind as a motive. In nature there is no mind in which the end is conscious of itself, but nevertheless nature moves towards the end, and the end is the cause of the movement. Thus the three causes named all melt into a single notion, which Aristotle calls the form of the thing. And this leaves only the material cause unreduced to any other. So we are left with the single ant.i.thesis of matter and form.

Now as matter and form are the fundamental categories of Aristotle's philosophy, by means of which he seeks to explain the entire universe, it is essential that we should thoroughly understand their characteristics. {275} First of all, matter and form are inseparable.

We think of them as separate in order to understand them clearly. And this is quite right, because they are opposite principles, and therefore they are separable in thought. But they are never separable in fact. There is no such thing as form without matter, or matter without form. Every existent thing, that is, every individual object, is a compound of matter and form. We may compare them in this respect to the material and the shape of a thing, though we must be careful not to think that form is merely shape. Geometry considers shapes as if they existed by themselves. But, in fact, we know that there are no such things as squares, circles, and triangles. There are only square objects, circular objects, etc. And as there are no shapes without objects, so there are no objects without shapes. We talk of things being "shapeless," but this only means that their shape is irregular or unusual. Some shape an object must have. Yet, though shape and matter are inseparable in fact, they are opposite principles, and are separable in thought. Geometry is quite right to treat shapes as if they existed by themselves, but it is nevertheless dealing with mere abstractions. Just in the same way, matter and form are never apart, and to think of form by itself or matter by itself is a mere abstraction. No such thing exists. In fact, to imagine that forms can exist by themselves was just the mistake of which, as we have seen, Aristotle accuses Plato. For the form is the Idea, and Plato imagined that Ideas exist in a world of their own.