Lectures on the Philosophy of the Human Mind (Vol. 1 of 3)

The percipient mind, in no one of its affections, can be said to be the mass of matter which it perceives, unless the separate existence, either of matter or of mind, be abandoned by us, the existence of which, Dr Reid would have been the last of philosophers to yield. He acknowledges that our perceptions are consequent on the presence of external bodies, not from any necessary connexion subsisting between them, but merely from the arrangement which the Deity, in his wisdom, has chosen to make of their mutual phenomena; which is surely to say, that the Deity has rendered the presence of the external object the occasion of that affection of the mind, which is termed perception; or, if it be not to say this, it is to say nothing. Whatever state of mind perception may be; whether a primary result of a peculiar power, or a mere secondary reference of association that follows the particular sensation, of which the reference is made, it is itself, in either view of it, but a state of the mind; and to be the external occasion or antecedent of this state of mind, since it is to produce, directly or indirectly, all which constitutes perception, is surely, therefore, to be perceived, or there must be something in the mere word perceived, different from the physical reality which it expresses.

The confusion of Dr Reid's notions on this subject, seems to have arisen from a cause, which has been the chief source of the general confusion that prevails in intellectual science; and, indeed, it was principally with the view of exhibiting this confusion, and its source, to you strongly, that I have dwelt so long on a criticism, which, to those among you who are not acquainted with the extensive and important applications that have been made of this doctrine, may, perhaps, have appeared of very little interest. Dr Reid, it is evident, was not sufficiently in the habit of considering the phenomena of the mind, – its perceptions, as well as its remembrances, judgments, passions, and all its other affections, whatever these may be, – in the light in which I have represented them to you, merely as the mind affected, in a certain manner, according to certain regular laws of succession, but as something more mysterious than the subject of this sequence of feelings; for, but for this notion of something more mysterious, the object of perception, and the external occasion of that state of mind which we term perception, must have conveyed precisely the same notion. To have a clear view of the phenomena of the mind, as mere affections or states of it, existing successively, and in a certain series, which we are able, therefore, to predict, in consequence of our knowledge of the past, is, I conceive, to have made the most important acquisition which the intellectual inquirer can make. To say, merely, that it is to have learned to distinguish that which may be known, from that which never can be known, and which it therefore would be an idle waste of labour to attempt to discover, – would be to say far too little. It is to see the mind, in a great measure, as it is in nature, divested of every thing foreign, passing instantly from thought to thought, from sensation to sensation, in almost endless variety of states, and differing as completely from that cumbrous representation of it, which philosophers are fond of representing to us, as the planets revolving freely in the immense space of our solar system, differ from those mimic orbs, which, without any principle of motion in themselves, are, as it were, dragged along, in the complex mechanism of our orreries.

In objecting, however, to Dr Reid's notion of perception, I am far from wishing to erase the word from our metaphysical vocabulary. On the contrary, I conceive it to be a very convenient one, if the meaning attached to it be sufficiently explained, by an analysis of the complex state of mind, which it denotes, and the use of it confined rigidly to cases in which it has this meaning. Sensation may exist, without any reference to an external cause, in the same manner as we may look at a picture, without thinking of the painter; or read a poem, without thinking of the poet, – or it may exist with reference to an external cause; and it is convenient, therefore, to confine the term sensation to the former of these cases, and perception to the latter. But, then, it must be understood, that the perception is nothing but the suggestion of ideas associated with the simple sensation, as it originally took place, – or is only another name for the original simple sensation itself, in the cases, if any there be, in which sensation involves immediately in itself, the belief of some existence external to the sentient mind, – or is only a mere inference, like all our other inferences, if it arise, in the manner in which I have endeavoured to explain to you, how the notions of extension and resistance in an external cause of our feelings, might arise, and be afterwards suggested in association with other feelings that had frequently accompanied it.

To give a brief summary, however, of the argument which I have urged; – in that state of acquired knowledge, long after the first elementary feelings of infancy, in which modified state alone, the phenomena of the mind can become to us objects of reflective analysis, certain feelings are referred by us to an external material cause. The feelings themselves, as primarily excited, are termed sensations, and, when followed by the reference to an external cause, receive the name of perceptions, which marks nothing more in addition to the primary sensations, than this very reference. But what is the reference itself, in consequence of which the new name is given? It is the suggestion of some extended resisting object, the presence of which had before been found to be attended with that particular sensation, which is now again referred to it. If we had had no sense but that of smell; no sense but that of taste; no sense but that of sound; no sense but that of sight; we could not have known the existence of extended resisting substances, and, therefore, could not have referred the pleasant or painful sensations of those classes to such external causes, more than we refer directly to an external cause, any painful or pleasing emotion, or other internal affection of the mind. In all but one class of our sensations, then, it is evident that what Dr Reid calls perception, as the operation of a peculiar mental faculty, is nothing more than a suggestion of memory or association, which differs in no respect from other suggestions arising from other coexistences or successions of feelings, equally uniform or frequent. It is only in a single class of sensations, therefore, – that which Dr Reid ascribes to touch, – that perception, which he regards as a peculiar faculty, extending to all our sensations, can be said to have any primary operation, even though we should agree with him in supposing, that our belief of extended resistance is not reducible by analysis, to any more general principles. If, however, my analysis of the complex notion of matter be just, perception, in its relation to our original sensations of touch, as much as in relation to the immediate feelings which we derive from smell, taste, sight, and hearing, is only one of the many operations of the suggesting or associating principle. But, even on his own principles, I repeat, it must be confined to the single class of feeling, which he considers as tactual, and is not an original principle, coextensive with all the original varieties of sensation. Even in the single class, to which it is thus, on his own principles, to be confined, it is not so much what he would term a faculty, as an intuitive belief, by which we are led irresistibly, on the existence of certain sensations, to ascribe these to causes that are external and corporeal; or, if we give the name of faculty to this peculiar form of intuition, we should give it equally to all our intuitions, and rank among our faculties, the belief of the continued order of Nature, or the belief of our own identity, as much as our belief of external things, if our senses themselves are unable to give us any information of them.

LECTURE XXVIII

ON DR REID'S SUPPOSED PROOF OF A MATERIAL WORLD – ON VISION – AND ANALYSIS OF THE FEELINGS ASCRIBED TO IT

In my Lecture of yesterday, Gentlemen, we were engaged in considering the grounds of Dr Reid's claim to the honour of detecting and exposing the fallacy of the hypothesis of ideas as images, or things, in the mind, distinct from the mind itself, – a claim which, though made by one who has many other indubitable titles to our respect and gratitude, we found, in this particular instance, to be inadmissible.

It appeared, on an examination of the original works of the eminent philosophers who preceded him for more than a century, and even of the common elementary treatises of the schools, that, though after the Peripatetic hypothesis of species had been universally or generally abandoned, the language of that hypothesis continued to subsist metaphorically, – as it continues with equal force at this moment, – it was only metaphorically that it did thus continue; and that when Dr Reid, therefore, conceived, – in proving ideas not to be self-existing things, separate and distinct from the percipient mind itself, – that he was confuting what every body believed, he merely assumed as real what was intended as metaphorical, and overthrew opinions which the authors, to whom he ascribes them, would themselves have been equally eager to overthrow. But there is yet another point, connected with the theory of perception, on which he is believed to have made an important addition to our metaphysical knowledge. I allude to his supposed proof of the existence of a material world. In this, too, we shall find, that he has truly added nothing to our former knowledge; that he has left us, in short, our belief as originally felt by us, but has not supplied us with the slightest evidence in addition to the force of that original belief itself, nor given any additional strength to that very belief, which before was confessedly irresistible.

The confutation of the scepticism on this subject, it is evident, may be attempted in two ways, – by shewing the arguments urged by the sceptic to be logically false; or by opposing to them the belief itself, as of evidence either directly intuitive, or the result, at least, of other intuitions, and early and universal associations and inferences, so irresistible after the first acquisitions of infancy, as to have then all the force of intuition itself. As long as Dr Reid confines himself to the latter of these pleas, he proceeds on safe ground; but his footing is not so firm when he assails the mere logic of the sceptic, – for the sceptical argument, as a mere play of reasoning, admits of no reply. It is vain for him to say, that the scepticism proceeding, as he thinks, on the belief of ideas in the mind, as the direct objects of perception, must fall with these ideas; for, though the scepticism may be consistent with the belief of ideas as separate existences in the mind, it does not depend, in the slightest degree, on their existence or non-existence. We have only to change the term ideas into the synonymous phrase affections or states of the mind, and the scepticism, if not stronger, is at least in strength exactly what it was before. In the one case the sceptic will say, that we are sensible of ideas only, not of external objects, which may have no resemblance to our ideas; in the other case, that perception is but a state of the mind as much as any of our other feelings, and that we are conscious only of this, and other states or affections of our mind, which have variously succeeded each other, and not of external objects, which themselves can be no parts of that train of mental consciousness. Whatever weight there may be in the former of these sceptical theories, exists, I may say, even with greater force, because with greater simplicity, in the second; and the task, therefore, of proving by logic, – if logical proof were requisite for our belief, – the existence of a material world, would remain as laborious as before, after the fullest confutation of the system, which might suppose perception to be carried on by the medium of little images of bodies in the mind.

So far, indeed, would the confutation of this hypothesis as to perception, – even if Dr Reid had truly overthrown it, – be from lessening the force of the scepticism as to the existence of matter, that, of two sceptics, one believing every thing with respect to ideas which Dr Reid supposed himself to have confuted, and the other believing ideas to be mere states of his mind, there can be no question, that the former would be the more easy to be overcome, since his belief would already involve the existence of SOMETHING separate from the mind; while the other might maintain, that all of which he was conscious, was the mere series of affections of his own mind, and that beyond this consciousness he could know nothing.

Against the argument of one, who founds his very argument on his consciousness merely, and professes to have no knowledge either of little images, or of any thing else beyond his consciousness, it would be as idle to urge, that ideas are not little images in the mind, as it would have been for a Cartesian to attempt to confute the Newtonian system of attraction, by a denial of the Ptolemaic spheres.

All that remains, then, to supply the place of logical demonstration, which would be needless where the belief is as strong as that of demonstration itself, is the paramount force of this universal and irresistible belief; and there is no fear that this can be weakened by any argument, or be less felt by him who denies it, than by him who asserts it. We are conscious, indeed, only of the feelings that are the momentary states of our own mind; but some of these it is absolutely impossible for us not to ascribe to causes that are external, and independent of us; and the belief of a system of external things, is one of these very states of the mind, which itself forms, and will ever form, a part of the train of our consciousness. This Mr Hume himself, the great sceptic whom Dr Reid opposes, admits as readily as Dr Reid himself: – “A Copernican or Ptolemaic, who supports each his different system of astronomy, may hope to produce a conviction, which will remain constant and durable, with his audience. A Stoic or Epicurean displays principles, which may not only be durable, but which have an effect on conduct and behaviour. But a Pyrrhonian cannot expect, that his philosophy will have any constant influence on the mind: or, if it had, that its influence would be beneficial to society. On the contrary, he must acknowledge, if he will acknowledge any thing, that all human life must perish, were his principles universally and steadily to prevail. All discourse, all action, would immediately cease; and men remain in a total lethargy, till the necessities of nature, unsatisfied, put an end to their miserable existence. It is true, so fatal an event is very little to be dreaded. Nature is always too strong for principle; and, though a Pyrrhonian may throw himself, or others, into a momentary amazement and confusion by his profound reasonings, the first and most trivial event in life will put to flight all his doubts and scruples, and leave him the same, in every point of action and speculation, with the philosophers of every other sect, or with those who never concerned themselves in any philosophical researches. When he awakes from his dream, he will be the first to join in the laugh against himself.”113 In what respect does this differ from the language of Dr Reid himself, when he says, that “the belief of a material world is older, and of more authority, than any principles of philosophy. It declines the tribunal of reason, and laughs at all the artillery of the logician.”114 Surely, if it decline the tribunal of reason, it is not by reasoning that it is to be supported, – even though the reasoner should have the great talents which Dr Reid unquestionably possessed.

The sceptic, and the orthodox philosopher of Dr Reid's school, thus come precisely to the same conclusion. The creed of each, on this point, is composed of two propositions, and of the same two propositions; the first of which is, that the existence of a system of things, such as we understand when we speak of an external world, cannot be proved by argument; and the second, that the belief of it is of a force, which is paramount to that of argument, and absolutely irresistible. The difference, and the only difference is, that, in asserting the same two propositions, the sceptic pronounces the first in a loud tone of voice, and the second in a whisper, – while his supposed antagonist passes rapidly over the first, and dwells on the second, with a tone of confidence. The negation in the one case, and the affirmation in the other case, are, however, precisely the same. To him, indeed, who considers the tone only, and not the meaning, there may seem to be a real strife of sentiment; but, if we neglect the tone, which is of no consequence, and attend to the meaning only of what is affirmed and denied by both, we shall not be able to discover even the slightest discrepancy. There is no argument of mere reasoning that can prove the existence of an external world; it is absolutely impossible for us not to believe in the existence of an external world. We may call these two propositions, then, a summary of the doctrine of Reid, or of the doctrine of Hume, as we please; for it is truly the common and equal doctrine of the two.

Though we have thus seen reason to deny to Dr Reid the merit commonly ascribed to him, on the points which we have been considering, relative to the theory of perception, I trust you will not on that account, be insensible to the merits which he truly possessed. He knows little, indeed, of the human mind, who does not know, how compatible many errors and misconceptions are with the brightest and most active energies of intellect. On this “Isthmus of a middle State,” of which Pope speaks, man, though not “reasoning but to err,” is yet subject to occasional error, even in his proudest reasonings. With all his wisdom, he is still but “darkly wise;” and with all the grandeur of his being, but “rudely great.”

VISION

Our inquiry into the nature of the sensations of touch, – or at least of those sensations, which are truly, and of others which are commonly, though, I think, falsely, ascribed to this organ, has led us into speculations, in the course of which I have been obliged to anticipate many remarks, that more peculiarly belong to the sense which still remains to be considered by us, – the sense of sight, that to which we owe so much of our most valuable information, with respect to nature, and so many of those pleasures, which the bounty of Him, who, has formed us to be happy, as well as to be wise, has so graciously intermingled, with all the primary means of our instruction.

The anticipations, into which I have been led, were necessary for throwing light on the subjects before considered, particularly on the complex feelings ascribed to touch, – the knowledge of which feelings, however, was still more necessary, for understanding fully the complex perceptions of this sense. It is thus scarcely possible, in science, to treat of one subject, without considering it in relation to some other subject, and often to subjects between which, on first view, it would be difficult to trace any relation. Every thing throws light upon every thing, – though the reflection, – which is, in many cases, so bright, as to force itself upon common eyes – may, in other cases, be so faint, as to be perceptible only to eyes of the nicest discernment. It may almost be said, that there is an universal affinity in truths, – like that universal attraction, which unites to each other, as one common system, the whole masses which are scattered through the infinity of space, and by which, as I have before remarked, the annihilation of a single particle of matter, in any one of these orbs, – however inconceivably slight its elementary modification might be of the general sum of attraction, – would in that very instant be productive of change throughout the universe. It is not easy to say, what any one science would have been, if any other science had not existed. How different did Astronomy become, in consequence of the accidental burning of a few sea-weeds upon the sand, to which the origin of glass has been ascribed; and, when we think of the universal accessions, which navigation has made to every department of knowledge, what an infinity of truths may be considered as almost starting into existence, at the moment, when the polarity of the magnet was first observed!

“True to the pole, by thee the pilot guidesHis steady helm, amid the struggling tides,Braves with broad sail the unmeasurable sea,Cleaves the dark air, and asks no star but thee.”115

The anticipations, which have been made, in the present instance, will be of advantage, in abridging much of the labour, which would have been necessary in treating of vision simply. I may now safely leave you, to make, for yourselves, the application of many arguments, on which I have dwelt at length, in treating of the other senses.

The organ of sight, as you well know, is the eye, – a machine of such exquisite and obvious adaptation to the effects produced by it, as to be, of itself, in demonstrating the existence of the Divine Being who contrived it, equal in force to many volumes of theology. The atheist, who has seen, and studied, its internal structure, and yet continues an atheist, may be fairly considered as beyond the power of mere argument to reclaim. The minute details of its structure, however, belong to the anatomist. It is enough for our purpose to know, that, by an apparatus of great simplicity, all the light, which, from every quarter strikes on the pellucid part of the ball of the eye, – and which if it continued to pass in the same direction, would thus produce one mingled and indistinct expanse of colour, – is so refracted, as it is termed, or bent from its former direction to certain focal points, as to be distributed again on the retina, in distinct portions, agreeing with the portions which come from each separate object, so exactly, as to form on it a miniature landscape of the scenery without. Nor is this all. That we may vary, at our pleasure, the field of this landscape, the ball of the eye is furnished with certain muscles, which enable us to direct it more particularly toward the objects which we wish to view; and according as the light which falls from these may be more or less intense, there are parts which minister to the sensibility of the eye, by increasing or diminishing in proportion the transparent aperture at which the light is admitted. There are, then, in this truly wonderful and beautiful process, in the first place, as determining what objects, in the wide scene around us, are to be visible at the moment, the contraction of certain muscles, on which the particular field of our vision depends, and which may almost be said to enable us to increase the extent of our field of vision, by enabling us to vary it at will; – in the second place, the external light, emitted from all the objects within this radiant field, which, on its arrival at the retina, is itself the direct object of vision; in the third place, the provision for increasing or diminishing the diameter of the pupil, in proportion to the quantity of that incident light; – in the fourth place, the apparatus, by which the dispersed rays of light are made to assume within the eye, the focal convergence necessary for distinct vision; – and lastly, the expansion of the optic nerve, as a part of the great sensorial organ, essential to sensation. The difference of the phenomena, produced by the varieties of the external light itself, is exhibited in almost every moment of our waking existence; and the diversities, arising from other parts of the process, are not less striking. There are peculiar diseases which affect the optic nerve, or other parts of the sensorial organ immediately connected with it, – there are other diseases which affect the refracting apparatus, – others which affect the iris, so as to prevent the enlargement or diminution of the pupil, when different quantities of light are poured on it, – others, which affect the muscles that vary the position of the ball, – and, in all these cases, we find, as might be expected, a corresponding difference of the phenomena.