‘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.