Chapter VII: The Systematic Philosophy of Aristotle (2)

It will be seen from the foregoing passage how strong a hold the old Greek notion of an encircling limit had on the mind of Aristotle, and how he transformed it back from the high intellectual significance given to it by Plato into its original sense of a mere space-enclosing figure. And it will also be seen how he credits his spheres with a full measure of that moving power which, according to his rather unfair criticism, the Platonic Ideas did not possess. His astronomy also supplied him with that series of graduated transitions between two extremes in which Greek thought so much delighted. The heavenly bodies mediate between God and the earth; partly active and partly passive, they both receive and communicate the moving creative impulse. The four terrestrial elements are moved in the various categories of substance, quantity, quality, and place; the aether moves in place only. God remains ‘without variableness or shadow of a change.’ Finally, by its absolute simplicity and purity, the aether mediates between the coarse matter perceived by our senses and the absolutely immaterial Nous, and is itself supposed to be pervaded by a similar gradation of fineness from top to bottom. Furthermore, the upper fire, which must not be confounded with flame, furnishes a connecting link between the aether and the other elements, being related to them as Form to Matter, or as agent to patient; and, when the elements are decomposed into their constituent qualities, hot and cold occupy a similar position with regard to wet and dry.

IV.

In mastering Aristotle’s cosmology, we have gained the key to his entire method of systematisation. Henceforth, the Stagirite has no secrets from us. Where we were formerly content to show that he erred, we can now show why he erred; by generalising his principles of arrangement, we can exhibit them still more clearly in their conflict with modern thought. The method, then, pursued by Aristotle is to divide his subject into two more or less unequal masses, one of which is supposed to be governed by necessary principles, admitting of certain demonstration; while the other is irregular, and can only be studied according to the rules of probable evidence. The parts of the one are homogeneous and concentrically disposed, the movements of each being controlled by that immediately outside and above it. The parts of the other are heterogeneous and distributed among a number of antithetical pairs, between whose members there is, or ought to be, a general equilibrium preserved, the whole system having a common centre which either oscillates from one extreme to another, or holds the balance between them. The second system is enclosed within the first, and is altogether dependent on it for the impulses determining its processes of metamorphosis and equilibration. Where the internal adjustments of a system to itself or of one system to the other are not consciously made, Aristotle calls them Nature. They are always adapted to secure its everlasting continuance either in an individual or a specific form. Actuality belongs more particularly to the first sphere, and possibility to the second, but both are, to a certain extent, represented in each.

We have already seen how this fundamental division is applied to the universe as a whole. But our philosopher is not content with classifying the phenomena as he finds them; he attempts to demonstrate the necessity of their dual existence; and in so doing is guilty of something very like a vicious circle. For, after proving from the terrestrial movements that there must be an eternal movement to keep them going, he now assumes the revolving aether, and argues that there must be a motionless solid centre for it to revolve round, although a geometrical axis would have served the purpose equally well. By a still more palpable fallacy, he proceeds to show that a body whose tendency is towards the centre, must, in the nature of things, be opposed by another body whose tendency is towards the circumference. In order to fill up the interval created by this opposition, two intermediate bodies are required, and thus we get the four elements—earth, water, air, and fire. These, again, are resolved into the antithetical couples, dry and wet, hot and cold, the possible combinations of which, by twos, give us the four elements once more. Earth is dry and cold, water cold and wet, air wet and hot, fire hot and dry; each adjacent pair having a quality in common, and each element being characterized by the excess of a particular quality; earth is especially dry, water cold, air wet, and fire hot. The common centre of each antithesis is what Aristotle calls the First Matter, the mere abstract unformed possibility of existence. This matter always combines two qualities, and has the power of oscillating from one quality to another, but it cannot, as a rule, simultaneously exchange both for their opposites. Earth may pass into water, exchanging dry for wet, but not so readily into air, which would necessitate a double exchange at the same moment.

Those who will may see in all this an anticipation of chemical substitution and double decomposition. We can assure them that it will be by no means the most absurd parallel discovered between ancient and modern ideas. It is possible, however, to trace a more real connexion between the Aristotelian physics and mediaeval thought. We do not of course mean the scholastic philosophy, for there never was the slightest doubt as to its derivation; we allude to the alchemy and astrology which did duty for positive science during so many centuries, and even overlapped it down to the time of Newton, himself an ardent alchemist. The superstitions of astrology originated independently of the peripatetic system, and probably long before it, but they were likely to be encouraged by it instead of being repressed, as they would have been by a less anthropomorphic philosophy. Aristotle himself, as we have seen, limited the action of the heavens on the sublunary sphere to their heating power; but, by crediting them with an immortal reason and the pursuit of ends unknown to us, he opened a wide field for conjecture as to what those ends were, and how they could be ascertained. That the stars and planets were always thinking and acting, but never about our affairs, was not a notion likely to be permanently accepted. Neither was it easy to believe that their various configurations, movements, and names (the last probably revealed by themselves) were entirely without significance. From such considerations to the casting of horoscopes is not a far remove. The Aristotelian chemistry would still more readily lend itself to the purposes of alchemy. If Nature is one vast process of transmutation, then particular bodies, such as the metals, not only may, but must be convertible into one another. And even those who rejected Aristotle’s logic with scorn still clung to his natural philosophy when it flattered their hopes of gain. Bacon kept the theory of substantial forms. His originality consisted in looking for a method by which any form, or assemblage of forms might be superinduced at pleasure on the underlying matter. The real development of knowledge pursued a far different course. The great discoverers of the sixteenth and seventeenth centuries achieved their success by absolutely reversing the method of Aristotle, by bringing into fruitful contact principles which he had condemned to barren isolation. They carried terrestrial physics into the heavens; they brought down the absoluteness and eternity of celestial law to earth; they showed that Aristotle’s antithetical qualities were merely quantitative distinctions. These they resolved into modes of motion; and they also resolved all motions into one, which was both rectilinear and perpetual. But they and their successors put an end to all dreams of transmutation, when they showed by another synthesis that all matter, at least within the limits of our experience, has the changeless consistency once attributed exclusively to the stellar spheres.

When Aristotle passes from the whole cosmos to the philosophy of life, his method of systematic division is less distinctly illustrated, but still it may be traced. The fundamental separation is between body and soul. The latter has a wider meaning than what we associate with it at present. It covers the psychic functions and the whole life of the organism, which, again, is not what we mean by life. For life with us is both individual and collective; it resides in each speck of protoplasm, and also in the consensus of the whole organism. With Aristotle it is more exclusively a central principle, the final cause of the organism, the power which holds it together, and by which it was originally shaped. Biology begins by determining the idea of the whole, and then considers the means by which it is realised. The psychic functions are arranged according to a system of teleological subordination. The lower precedes the higher in time, but is logically necessitated by it. Thus nutrition, or the vegetative life in general, must be studied in close connexion with sensation and impulse, or animal life; and this, again, with thought or pure reasoning. On the other hand, anatomy and physiology are considered from a purely chemical and mechanical point of view. A vital purpose is, indeed, assigned to every organ, but with no more reference to its specifically vital properties than if it formed part of a steam engine. Here, as always with Aristotle, the idea of moderation determines the point of view whence the inferior or material system is to be studied. Organic tissue is made up of the four elemental principles—hot, cold, wet, and dry—mixed together in proper proportions; and the object of organic function is to maintain them in due equilibrium, an end effected by the regulating power of the soul, which, accordingly, has its seat in the heart or centre of the body. It has been already shown how, in endeavouring to work out this chimerical theory, Aristotle went much further astray from the truth than sundry other Greek physiologists less biassed by the requirements of a symmetrical method.

After the formal and material elements of life have been separately discussed, there comes an account of the process by which they are first brought into connexion, for this is how Aristotle views generation. With him it is the information of matter by psychic force; and his notions about the part which each parent plays in the production of a new being are vitiated throughout by this mistaken assumption. Nevertheless his treatise on the subject is, for its time, one of the most wonderful works ever written, and, as we are told on good authority,[257] is now less antiquated than the corresponding researches of Harvey. The philosopher’s peculiar genius for observation, analysis, and comparison will partly account for his success; but, if we mistake not, there is another and less obvious reason. Here the fatal separation of form and matter was, except at first starting, precluded by the very idea of generation; and the teleological principle of spontaneous efforts to realise a predetermined end was, as it happened, perfectly in accordance with the facts themselves.

And now, looking back on his cosmology, we can see that Aristotle was never so near the truth as when he tried to bridge over the gulf between his two spheres, the one corruptible and the other eternal, by the idea of motion considered as a specific property of all matter, and persisting through all time; as a link between the celestial revolutions and the changes occurring on or near the earth’s surface; and, finally, as the direct cause of heat, the great agent acting in opposition to gravity—which last view may have suggested Bacon’s capital discovery, that heat is itself a mode of motion.

Another method by which Aristotle strove to overcome the antithesis between life as a mechanical arrangement and life as a metaphysical conception, was the newly created study of comparative anatomy. The variations in structure and function which accompany variations in the environment, though statically and not dynamically conceived, bring us very near to the truth that biological phenomena are subject to the same general laws of causation as all other phenomena; and it is this truth which, in the science of life, corresponds to the identification of terrestrial with celestial physics in the science of general mechanics. Vitality is not an individualised principle stationed in the heart and serving only to balance opposite forces against one another; but it is diffused through all the tissues, and bestows on them that extraordinary plasticity which responds to the actions of the environment by spontaneous variations capable of being summed up in any direction, and so creating entirely new organic forms without the intervention of any supernatural agency.

V.

We have now to consider how Aristotle treats psychology, not in connexion with biology, but as a distinct science—a separation not quite consistent with his own definition of soul, but forced on him by the traditions of Greek philosophy and by the nature of things. Here the fundamental antithesis assumes a three-fold form. First the theoretical activity of mind is distinguished from its practical activity; the one being exercised on things which cannot, the other on things which can, be changed. Again, a similar distinction prevails within the special province of each. Where truth is the object, knowledge stands opposed to sense; where good is sought, reason rises superior to passion. The one antithesis had been introduced into philosophy by the early physicists, the other by Socrates. They were confounded in the psychology of Plato, and Aristotle had the merit of separating them once more. Yet even he preserves a certain artificial parallelism between them by using the common name Nous, or reason, to denote the controlling member in each. To make his anthropology still more complex, there is a third antithesis to be taken into account, that between the individual and the community, which also sometimes slides into a partial coincidence with the other two.

Aristotle’s treatise on the soul is mainly devoted to a description of the theoretical faculties—sense, and thought or reason. By sense we become acquainted with the material qualities of things; by thought with their forms or ideas. It has been already mentioned that, according to our philosopher, the organism is a system of contrary forces held in equilibrium by the soul, whose seat he supposes to be in the heart. We now learn that every sensation is a disturbance of this equilibrium. In other words, the sensorium being virtually any and every mode of matter, is raised from possibility to actuality by the presence of some one force, such as heat or cold, in sufficient strength to incline the balance that way. Here we have, quite in Aristotle’s usual style, a description instead of an explanation. The atomic notion of thin films thrown off from the object of sense, and falling on the organs of sight or touch, was but a crude guess; still it has more affinity with the discoveries of a Young or a Helmholtz than scholastic phrases about potentiality and actuality. That sensation implies a disturbance of equilibrium is, indeed, an important truth; only, the equilibrium must be conceived as a balance, not of possible sensations, but of molecular states; that is to say, it must be interpreted according to the atomic theory.

Aristotle is more successful when he proceeds to discuss the imagination. He explains it to be a continuance of the movement originally communicated by the felt object to the organ of sense, kept up in the absence of the object itself;—as near an approach to the truth as could be made in his time. And he is also right in saying that the operations of reason are only made possible by the help of what he calls phantasms—that is, faint reproductions of sensations. In addition to this, he points out the connexion between memory and imagination, and enumerates the laws of association briefly, but with great accuracy. He is, however, altogether unaware of their scope. So far from using them to explain all the mental processes, he does not even see that they account for involuntary reminiscence, and limits them to the voluntary operation by which we recall a missing name or other image to consciousness.

So far, Aristotle regards the soul as a function, or energy, or perfection of the body, from which it can no more be separated than vision from the eye. It is otherwise with the part of mind which he calls Nous, or Reason—the faculty which takes cognisance of abstract ideas or the pure forms of things. This corresponds, in the microcosm, to the eternal Nous of the macrocosm, and, like it, is absolutely immaterial, not depending for its activity on the exercise of any bodily organ. There is, however, a general analogy between sensation and thought considered as processes of cognition. Previous to experience, the Nous is no thought in particular, but merely a possibility of thinking, like a smooth wax tablet waiting to be written on. It is determined to some particular idea by contact with the objective forms of things, and in this determination is raised from power to actuality. The law of moderation, however, does not apply to thought. Excessive stimulation is first injurious and then destructive to the organs of sense, but we cannot have too much of an idea; the more intense it is the better are we able to conceive all the ideas that come under it, just because ideation is an incorporeal process. And there seems to be this further distinction between sensation and thought, that the latter is much more completely identified with its object than the former; it is in the very act of imprinting themselves on the Nous that the forms of things become perfectly detached from matter, and so attain their final realisation. It is only in our consciousness that the eternal ideas of transient phenomena become conscious of themselves. Such, we take it, is the true interpretation of Aristotle’s famous distinction between an active and a passive Nous. The one, he tells us, _makes_ whatever the other is _made_. The active Nous is like light raising colours from possibility to actuality. It is eternal, but we have no remembrance of its past existence, because the passive Nous, without which it can think nothing, is perishable.

It will be seen that we do not consider the two kinds of Nous to differ from each other as a higher and a lower faculty. This, in our opinion, has been the great mistake of the commentators, of those, at least, who do not identify the active Nous with God, or with some agency emanating from God—a hypothesis utterly inconsistent with Aristotle’s theology. They describe it as a faculty, and as concerned with some higher kind of knowledge than what lies within the reach of the passive Nous.[258] But with Aristotle faculty is always a potentiality and a passive recipient, whereas the creative reason is expressly declared to be an actuality, which, in this connexion, can mean nothing but an individual idea. The difficulty is to understand why the objective forms of things should suddenly be spoken of as existing within the mind, and denominated by a term carrying with it such subjective associations as Nous; a difficulty not diminished by the mysterious comparison with light in its relation to colour, an illustration which, in this instance, has only made the darkness visible. We believe that Aristotle was led to express himself as he did by the following considerations. He began by simply conceiving that, just as the senses were raised from potency to actuality through contact with the corresponding qualities in external objects, so also was the reasoning faculty moulded into particular thoughts through contact with the particular things embodying them; thus, for instance, it was led to conceive the general idea of straightness by actual experience of straight lines. It then, perhaps, occurred to him that one and the same object could not produce two such profoundly different impressions as a sensation and a thought; that mind was opposed to external realities by the attribute of self-consciousness; and that a form inherent in matter could not directly impress itself on an immaterial substance. The idea of a creative Nous was, we think, devised in order to escape from these perplexities. The ideal forms of things are carried into the mind, together with the sensations, and in passing through the imagination, become purified from the matter previously associated with them. Thus they may be conceived as part of the mind—in, though not yet of it—and as acting on its highest faculty, the passive Nous. And, by a kind of anticipation, they are called by the name of what they become completely identified with in cognition. As forms of things they are eternal; as thoughts they are self-conscious; while, in both capacities, they are creative, and their creative activity is an essentially immaterial process. Here we have the old confusion between form and function; the old inability to reconcile the claims of the universal and the particular in knowledge and existence. After all, Aristotle is obliged to extract an actuality from the meeting of two possibilities, instead of from the meeting of an actuality and a possibility. Probably the weakness of his own theory did not escape him, for he never subsequently recurs to it.[259]

Aristotle’s work on reproduction is supposed by many to contain a reference to his distinction between the two Reasons, but we are convinced that this is a mistake. What we are told is that at the very first formation of a new being, the vegetative soul, being an exclusively corporeal function, is precontained in the elements furnished by the female; that the sensitive soul is contributed by the male (being, apparently, engendered in the semen by the vital heat of the parent organism); and, finally, that the rational soul, although entirely immaterial, is also carried in with the semen, into which it has first been introduced from without, but where, or when, or how is not more particularly specified.[260] But even were the genetic theory in question perfectly cleared up, it would still throw no light on the distinction between active and passive reason, as the latter alone can be understood by the rational soul to which it refers. For we are expressly informed—what indeed hardly required to be stated—that the embryonic souls exist not in act but in potency.[261] It seems, therefore, that Mr. Edwin Wallace is doubly mistaken when he quotes a sentence from this passage in justification of his statement, that ‘Aristotle would seem almost to identify’ the creative reason ‘with God as the eternal and omnipresent thinker;’[262] first, because it does not refer to the creative Nous at all; and, secondly, because, if it did, the words would not stand the meaning which he puts upon them.[263]

But if even so little as this remains unproved, what are we to think of the astounding assertion, that ‘Aristotle’s theory of a creative reason, fragmentary as that theory is left, is the answer to all materialistic theories of the universe. To Aristotle, as to a subtle Scottish preacher,[264] “the real pre-supposition of all knowledge, or the thought which is the _prius_ of all things, is not the individual’s consciousness of himself as individual, but a thought or self-consciousness which is beyond all individual selves, which is the unity of all individual selves, and their objects, of all thinkers and all objects of thought.”’[265] How can materialism or anything else be possibly refuted by a theory which is so obscurely set forth that no two interpreters are able to agree in their explanation of it? And even were it stated with perfect clearness and fulness, how can any hypothesis be refuted by a mere dogmatic declaration of Aristotle? Are we back in the Middle Ages that his _ipse dixit_ is to decide questions now raised with far ampler means of discussion than he could possess? As to Principal Caird’s metaphysics, we have no wish to dispute their theoretic accuracy, and can only admire the liberality of a Church in which propositions so utterly destructive of traditional orthodoxy are allowed to be preached. But one thing we are certain of, and that is, that whether or not they are consistent with Christian theism, they are utterly inconsistent with Aristotelian principles. Which is the ‘thought or self-consciousness’ referred to, a possibility or an actuality? If the former, it is not a _prius_, nor is it the creative reason. If the latter, it cannot transcend all or any individual selves, for, with Aristotle, individuals are the sole reality, and the supreme being of his system is pre-eminently individual; neither can it unify them, for, according to Aristotle, two things which are two in actuality cannot be one in actuality.[266]

We now turn to Sir A. Grant, who, as was mentioned at the beginning of the last chapter, makes Aristotle a supporter of the late Prof. Ferrier. We will state the learned Principal’s view in his own words:—

‘His utterances on this subject [the existence of an external world] are perhaps chiefly to be found in the third book of his treatise “On the Soul,” beginning with the fourth chapter. On turning to them we see that he never separates existence from knowledge. “A thing in actual existence,” he says, “is identical with the knowledge of that thing.” Again, “The possible existence of a thing is identical with the possibility in us of perceiving or knowing it.” Thus, until a thing is perceived or known, it can only be said to have a potential or possible existence. And from this a doctrine very similar to that of Ferrier might be deduced, that “nothing exists except _plus_ me,”—that is to say, in relation to some mind perceiving it.‘ (_Aristotle_, p. 165.)

After much searching, we have not been able to find the originals of the two passages quoted by Sir A. Grant. We have, however, found others setting forth the doctrine of Natural Realism with a clearness which leaves nothing to be desired. Aristotle tells us that former naturalists were wrong when they said that there could be no black or white without vision, and no taste without tasting; that is, they were right about the actuality, and wrong about the possibility; for, as he explains, our sensations are produced by the action of external bodies on the appropriate organs, the activity being the same while the existence is different. A sonorous body produces a sound in our hearing; the sound perceived and the action of the body are identical, but not their existence; for, he adds, the hearer need not be always listening, nor the sonorous body sounding; and so with all the other senses.[267]

This is not making the _percipi_ of objects their _esse_. Again, in the eighth chapter he tells us that the soul is ‘in a certain way’ (πῶς) all things, since all things are either sensible or cogitable; and then he proceeds to explain what is meant by ‘in a certain way.’ Sense and knowledge are distributed over things in such wise that their possibility is the possibility, and their actuality the actuality, of the things. They must, then, be either the things themselves or their forms. ‘_But the things themselves they are surely not_, for the stone is not in the soul, but its form.’ In the _Metaphysics_, Aristotle expresses himself to the same effect, but even more explicitly. Criticising the Protagorean doctrine, he reduces it to an absurdity by urging that if there were nothing but sensibles, then nothing at all could exist in the absence of animated beings, for without them there would be no sensation. He admits that in the case supposed there would be neither feelings nor felt objects, since these presuppose a sentient subject; but adds, that for the substances (τὰ ὑποκείμενα) which produce the feeling not to exist is impossible; ‘for there is something else besides the feeling which must necessarily exist before it.’[268] And immediately afterwards he clinches the argument by observing that if appearances were the only truth, there would be no independent existences, and everything would be relative, since appearances exist only in relation to some one to whom they appear. Now we need hardly say that this universal relativity was precisely what Ferrier contended for.

Sir A. Grant is on stronger, or rather on more inaccessible ground, when he uses the distinction between the two reasons as involving a sort of idealistic theory, because here Aristotle’s meaning is much less clearly expressed. Yet, if our interpretation be the correct one, if the creative Nous simply means the forms of things acting through the imagination on the possibilities of subjective conception, Aristotle’s view will be exactly the reverse of that contended for by Sir Alexander; thought, instead of moulding, will itself be moulded by external reality. In no case have we a right to set an obscure and disputed passage against Aristotle’s distinct, emphatic, and reiterated declarations, that sensation and ideation are substantially analogous processes, taken together with his equally distinct declaration, that the objects of sensation are independent of our feelings. We think, indeed, that Sir A. Grant will find, on reconsideration, that he is proving too much. For, if the things which reason creates were external to the mind, then Aristotle would go at least as far as those ‘extreme German idealists’ from whom his expositor is anxious to separate him. Finally, we would observe that to set up Aristotle’s distinction between form and matter in opposition to the materialistic theories of the present day, shows a profound misconception of its meaning. Form and matter are nowhere distinguished from one another as subject and object. Form simply means the attributes of a thing, the entire aggregate of its differential characteristics. But that this does not of itself amount to conscious reason we are told by Aristotle himself.[269] On the other hand, the ‘matter’ to which ‘some philosophers’ attribute ‘an independent existence,’ is not his ‘matter’ at all, but just the sum of things _minus_ consciousness. The Stagirite did not, it is true, believe in the possibility of such a universe, but only (as we have shown) because he was not acquainted with the highest laws of motion. Yet, even taking ‘matter’ in his own technical sense, Aristotle would have agreed with Prof. Tyndall, that it contained the promise and the potency of all future life, reason alone excepted. He tells us very clearly that the sensitive soul is a somatic function, something which, although not body, belongs to body; and this we conceive is all that any materialist would now contend for.[270] And having gone so far, there really was nothing to prevent him from going a step farther, had he only been acquainted with the dependence of all intelligence on nervous action. At any rate, the tendency is now to obliterate the distinction where he drew it, and to substitute for it another distinction which he neglected. While all functions of consciousness, from the most elementary sensation to the most complex reasoning, seem to pass into one another by imperceptible gradations, consciousness in general is still separated from objective existence by an impassable chasm; and if there is any hope of reconciling them it lies in the absolute idealism which he so summarily rejected. What we have had occasion repeatedly to point out in other departments of his system, is verified once more in his psychology. The progress of thought has resulted from a reunion of the principles between which he drew a rigid demarcation. We have found that perception can only be understood as a process essentially homogeneous with the highest thought, and neither more nor less immaterial than it is. On the objective side, both may be resolved into sensori-motor actions; on the subjective side, into groups of related feelings. And here, also, we have to note that when Aristotle anticipates modern thought, it is through his one great mediating, synthetic conception. He observes incidentally that our knowledge of size and shape is acquired, not through the special senses, but by motion—an aperçu much in advance of Locke.[271]

If there are any who value Aristotle as a champion of spiritualism, they must take him with his encumbrances. If his philosophy proves that one part of the soul is immaterial, it proves equally that the soul, taking it altogether, is perishable. Not only does he reject Plato’s metempsychosis as inconsistent with physiology, but he declares that affection, memory, and reasoning are functions not of the eternal Nous, but of the whole man, and come to an end with his dissolution. As to the active Nous, he tells us that it cannot think without the assistance of the passive Nous, which is mortal. And there are various passages in the ‘Nicomachean Ethics’ showing that he had faced this negation of a future life, and was perfectly resigned to its consequences.[272] At one period of his life, probably when under the immediate influence of Plato, he had indulged in dreams of immortality; but a profounder acquaintance with natural science sufficed to dissipate them. Perhaps a lingering veneration for his teacher made him purposely use ambiguous language in reference to the eternity of that creative reason which he had so closely associated with self-consciousness. It may remind us of Spinoza’s celebrated proposition, _Sentimus experimurque nos aeternos esse_, words absolutely disconnected with the hope of a continued existence of the individual after death, but apparently intended to enlist some of the sentiment associated with that belief on the side of the writer’s own philosophy.

On the other hand, the spirit of Plato’s religion survived in the teaching of his disciple under a new form. The idea of an eternal personality was, as it were, unified and made objective by being transferred from the human to the divine; and so each philosopher developes an aspect of religious faith which is wanting in the other, thereby illustrating the tendencies, to some extent mutually exclusive; which divide all theology between them. It remains to observe that if even Aristotle’s theism is inconsistent with the Catholic faith, much more must his psychology be its direct negation. _The_ Philosophy of _the_ Philosopher is as fatal to the Church’s doctrine of future rewards and punishments as it is to her doctrine of divine interference with the usual order of nature.

VI.

We now pass to the consideration of Aristotle’s most important achievement—his system of logic. And as, here also, we shall find much to criticise, it is as well to begin by saying that, in our opinion, his contributions to the science are the most valuable ever made, and perhaps have done more to advance it than all other writings on the same subject put together.

The principal business of reason is, as we have seen, to form abstract ideas or concepts of things. But before the time of Aristotle it had already been discovered that concepts, or rather the terms expressing them, were capable of being united in propositions which might be either true or false, and whose truth might be a matter either of certainty or of simple opinion. Now, in modern psychology, down to the most recent times, it has always been assumed that, just as there is an intellectual faculty or operation called abstraction corresponding to the terms of which a proposition is composed, so also there is a faculty or operation called judgment corresponding to the entire proposition. Sometimes, again, the third operation, which consists in linking propositions together to form syllogisms, is assigned to a distinct faculty called reason; sometimes all three are regarded as ascending steps in a single fundamental process. Neither Plato nor Aristotle, however, had thought out the subject so scientifically. To both the framing, or rather the discovery, of concepts was by far the most important business of a philosopher, judgment and reasoning being merely subsidiary to it. Hence, while in one part of their logic they were realists and conceptualists, in other parts they were nominalists. Abstract names and the definitions unfolding their connotation corresponded to actual entities in Nature—the eternal Ideas of the one and the substantial forms of the other—as well as to mental representations about whose existence they were agreed, while ascribing to them a different origin. But they did not in like manner treat propositions as the expression of natural laws without, or of judgments within, the mind; while reasoning they regarded much more as an art of thinking, a method for the discovery of ideas, than as the Systematisation of a process spontaneously performed by every human being without knowing it; and, even as such, their tendency is to connect it with the theory of definition rather than with the theory of synthetic propositions. Some approach to a realistic view is, indeed, made by both. The restless and penetrating thought of Plato had, probably towards the close of his career, led him to enquire into the mutual relations of those Ideas which he had at first been inclined to regard as absolutely distinct. He shows us in the _Sophist_ how the most abstract notions, such as Being, Identity, and so forth, must, to a certain extent, partake of each other’s nature; and when their relationship does not lie on the surface, he seeks to establish it by the interposition of a third idea obviously connected with both. In the later books of the _Republic_ he also points to a scheme for arranging his Ideas according to a fixed hierarchy resembling the concatenation of mathematical proofs, by ascending and descending whose successive gradations the mind is to become familiarised with absolute truth; and we shall presently see how Aristotle, following in the same track, sought for a counterpart to his syllogistic method in the objective order of things. Nevertheless, with him, as well as with his master, science was not what it is with us, a study of laws, a perpetually growing body of truth, but a process of definition and classification, a systematisation of what had already been perceived and thought.

It was from the initiative of Socrates that logic received this direction. By insisting on the supreme importance of definition, he drew away attention from the propositions which add to our knowledge, and concentrated it on those which only fix with precision the meaning of words. Yet, in so doing he was influenced quite as much by the spirit of the older physical philosophy, which he denounced, as by the necessities of the new humanistic culture, which he helped to introduce. His definitions were, in truth, the reproduction, on a very minute scale, of those attempts to formulate the whole universe which busied the earliest Ionian speculation. Following the natural tendency of Greek thought, and the powerful attraction of cosmic philosophy, an effort was speedily made to generalise and connect these partial definitions until they grew into a system of universal classification. It was when, under the influence of a new analysis, this system threatened to fall to pieces, that a rudimentary doctrine of judgment first made its appearance. The structure of a grammatical sentence was used to explain how objective ideas could, in a manner, overlap and adhere to one another. Hence propositions, which, as the expression of general truths, were destined to become the beginning and end of thought, remained at first strictly subordinated to the individual concepts that they linked and reconciled.

With Aristotle propositions assumed a new importance. He looked on them as mediating, not only between concepts, but also between conception and reasoning. Still, neither as a psychologist nor as a logician did he appreciate them at their real value. A very brief consideration is given to judgment in his work on the soul, and we are left in doubt whether it is a function of Nous alone or of Nous combined with some other faculty. Setting aside the treatise on Interpretation, which is probably spurious, and, at any rate, throws no new light on the subject, we may gather from his logical writings half a dozen different suggestions towards a classification of propositions, based partly on their form and partly on their import. In all we find an evident tendency to apply, here also, his grand fundamental distinction between the sphere of uniformity and the sphere of change and opposition. All propositions are either universal or particular; either positive or negative; either necessary or actual or contingent; either reciprocating or not reciprocating; either essential or accidental; either answering to the first question in the categories, or to one of the other nine.[273] But nowhere is any attempt made to combine and systematise these various points of view.

In the theory of reasoning the simple proposition is taken as a starting-point; but instead of deducing the syllogism from the synthesis of two premises, Aristotle reaches the premises through the conclusion. He tells us, indeed, that reasoning is a way of discovering from what we know, something that we did not know before. With him, however, it is really a process not of discovery but of proof. He starts with the conclusion, analyses it into predicate and subject or major and minor, and then, by a further analysis, introduces a middle term connecting the two. Thus, we begin with the proposition, ‘Caius is mortal,’ and prove it by interpolating the notion humanity between its two extremes. From this point of view the premises are merely a temporary scaffolding for bringing the major and minor into connexion with the middle term; and this is also the reason why Aristotle recognises three syllogistic figures only, instead of the four admitted by later logicians. For, the middle may either be contained in one extreme and contain the other, which gives us the first figure; or it may contain both, which gives the second figure; or be contained in both, which gives the third; and this is an exhaustive enumeration of the possible combinations.[274]

We have here, also, the secret of that elaborate machinery devised for the very unnecessary purpose of converting syllogisms of the second and third figure into syllogisms of the first, which is one of the Stagirite’s principal contributions to logic. For it is only in the first figure that the notion by which the extremes are either united or held apart is really a middle term, that is to say, really comes between the others. The distinction between perfect and imperfect syllogisms also serves to illustrate Aristotle’s systematic division between the necessary and the contingent. The method of proof by inclusion corresponds in its unconditioned and independent validity to the concentric arrangement of the supernal spheres; the second and third figures, with their conversions and reductions, to the sublunary sphere in its helpless dependence on the celestial revolutions, and its transformations of the elements into one another.

The rules which Aristotle gives us for the conversion of propositions are no doubt highly instructive, and throw great light on their meaning; but one cannot help observing that such a process as conversion ought, on his own principles, to have been inadmissible. With Plato, the copulation of subject and predicate corresponded to an almost mechanical juxtaposition of two self-existent ideas. It was, therefore, a matter of indifference in what order they were placed. Aristotle, on the other hand, after insisting on the restoration of the concrete object, and reducing general notions to an analysis of its particular aspects, could not but make the predicate subordinate to, and dependent on, the subject—a relation which altogether excludes the logical possibility of making them interchangeable with one another.[275]

The antithetical structure of the whole system is reproduced even in the first syllogistic figure, where there is a similar opposition between the first mood, by which alone universal affirmatives can be obtained, and the remaining three, whose conclusions are either negative or particular, or both. And the complicated rules for testing the validity of those syllogisms in which the premises are distinguished as necessary, actual, and possible, are still more obviously based on Aristotle’s false metaphysical distinctions; so that with the overthrow of those distinctions large portions of the _Analytics_ lose their entire value for modern students.

On the other hand, a theory of reasoning based on the relations of concepts, instead of on the relations of judgments, necessarily leaves out of account the whole doctrine of hypothetical and disjunctive propositions, together with that of the syllogisms based on them; since the elements of which they are composed are themselves propositions. And this inevitable omission is the more remarkable because alternative and, to a less extent, hypothetical arguments form the staple of Aristotle’s own dialectic; while categorical reasoning never occurs in it at all. His constant method is to enumerate all possible views of a subject, and examine them one after the other, rejecting those which are untenable, and resting content with the remainder. In other words, he reaches his positive conclusions through a series of negative premises representing a process of gradual elimination. The _First Analytics_ is itself an admirable instance of his favourite method. Every possible combination of terms is discussed, and the valid moods are sifted out from a much greater number of illegitimate syllogisms. The dialectic of Socrates and Plato followed the same procedure. It was essentially experimental—a method of trial, elimination, and selection. On going back still further, we find that when there is any reasoning at all in Homer, it is conducted after the same fashion. Hector, in his soliloquy before the Scaean Gate, imagines three alternative courses, together exhausting the possibilities of the situation. He may either retreat within the walls, or offer terms of peace to Achilles, or fight. The first two alternatives being rejected, nothing remains but the third. This is the most elaborate example; but on many other occasions Homer’s actors are represented as hesitating between two courses, and finally deciding on one of them.

Disjunction is, in truth, the primordial form of all reasoning, out of which the other forms are successively evolved; and, as such, it is common to man with the lower animals. You are taking a walk in the country with your dog. You come to a stream and jump over it. On measuring the distance with his eye, the animal is afraid to follow you. After waiting a little, he first runs up stream in search of a crossing, and, finding none, returns to look for one in the opposite direction. Failing there also, he comes back once more, and either ventures on the leap or makes his way home by some other route. Now, on considering the matter a little more closely, we shall find that hypothetical reasoning takes its rise from the examination of each separate alternative presented by a disjunctive premise. A plurality of courses being open to us, we consider what will ensue on the acceptance or rejection of each. The dog in our illustration thinks (after a canine fashion) that if he jumps he may fall in; if he does not, he will be left behind. Hector will not take refuge within the walls, because, if he does, Polydamas will triumph over him; nor will he offer terms of peace, because, if he does, Achilles will refuse them. Once more, categorical reasoning is developed out of hypothetical reasoning by the necessity of deducing consequences from a general rule. Hector must have argued from the known characters of Polydamas and Achilles, that in certain circumstances they would act after a certain manner. We may add, that this progress of conscious reasoning is a reproduction of the unconscious logic according to which life itself is evolved. All sorts of combinations are spontaneously produced, which, in consequence of the struggle for existence, cannot all survive. Those adapted to the conditions of life are selected, on trial, at the expense of the rest; and their adaptation or non-adaptation is determined in accordance with categorical laws. Furthermore, the framing of a disjunctive proposition necessitates the systematic distribution of possibilities under mutually exclusive heads, thus involving the logical processes of definition, division, and classification. Dialectic, as Plato understood it, consisted almost entirely in the joint performance of these operations;—a process which Aristotle regards as the immediate but very imperfect precursor of his own syllogistic method.[276] You cannot, he says, prove anything by dividing, for instance, all living things into the two classes, mortal and immortal; unless, indeed, you assume the very point under discussion—to which class a particular species belongs. Yet this is how he constantly reasons himself; and even demonstrative reasoning, as he interprets it, implies the possession of a ready-made classification. For, according to him, it consists exclusively of propositions which predicate some essential attribute of a thing—in other words, some attribute already included in the definition of the subject; and a continuous series of such definitions can only be given by a fixed classification of things.

VII.

We have endeavoured to show that Aristotle’s account of the syllogism is redundant on the one side and defective on the other, both errors being due to a false analysis of the reasoning process itself, combined with a false metaphysical philosophy. The same evil influences tell with much greater effect on his theory of applied reasoning. Here the fundamental division, corresponding to that between heaven and earth in the cosmos, is between demonstration and dialectic or experimental reasoning. The one starts with first principles of unquestionable validity, the other with principles the validity of which is to be tested by their consequences. Stated in its most abstract form, the distinction is sound, and very nearly prefigures the modern division between deduction and induction, the process by which general laws are applied, and the process by which they are established. Aristotle, however, committed two great mistakes; he thought that each method corresponded to an entirely different order of phenomena: and he thought that both were concerned for the most part with definitions. The _Posterior Analytics_, which contains his theory of demonstration, answers to the astronomical portion of his physics; it is the doctrine of eternal and necessary truth. And just as his ontology distinguishes between the Prime Mover himself unmoved and the eternal movement produced by his influence, so also his logic distinguishes between infallible first principles and the truths derived from them, the latter being, in his opinion, of inferior value. Now, according to Aristotle, these first principles are definitions, and it is to this fact that their self-evident certainty is due. At the same time they are not verbal but real definitions—that is to say, the universal forms of things in themselves as made manifest to the eye of reason, or rather, stamped upon it like the impression of a signet-ring on wax. And, by a further refinement, he seems to distinguish between the concept as a whole and the separate marks which make it up, these last being the ultimate elements of all existence, and as much beyond its complex forms as Nous is beyond reasoned truth.

Such a view was essentially unfavourable to the progress of science, assigning, as it did, a higher dignity to meagre and very questionable abstractions than to the far-reaching combinations by which alone we are enabled to unravel the inmost texture of visible phenomena. Instead of using reason to supplement sense, Aristotle turned it into a more subtle and universal kind of sense; and if this disastrous assimilation was to a certain extent imposed upon him by the traditions of Athenian thought, it harmonised admirably with the descriptive and superficial character of his own intelligence. Much was also due to the method of geometry, which in his time had already assumed the form made familiar to us by Euclid’s _Elements_. The employment of axioms side by side with definitions, might, indeed, have drawn his attention to the existence and importance of judgments which, in Kantian terminology, are not analytic but synthetic—that is, which add to the content of a notion instead of simply analysing it. But although he mentions axioms, and states that mathematical theorems are deduced from them, no suspicion of their essential difference from definitions, or of the typical significance which they were destined to assume in the theory of reasoning, seems ever to have crossed his mind; otherwise he could hardly have failed to ask how we come by our knowledge of them, and to what they correspond in Nature. On the whole, it seems likely that he looked on them as an analysis of our ideas, differing only from definition proper by the generality of its application; for he names the law of contradiction as the most important of all axioms, and that from which the others proceed;[277] next to it he places the law of excluded middle, which is also analytical; and his only other example is, that if equals be taken from equals the remainders are equal, a judgment the synthetic character of which is by no means clear, and has occasionally been disputed.[278]