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 attitude 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 substituted 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.
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 associated 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 analysis 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 adventitious. 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.