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“be by the senses: but by the senses we have no knowledge but of “our sensations only; and our sensations, which are attributes of “Mind, can have no resemblance to any qualities of a thing that ** is inanimate.” It is observed by Dr Reid, that the only proposition in this demonstration, which admits of doubt, is, that by our senses we have the knowledge of our sensations only, and of nothing else. Grant this, and the conclusion is irresistible.—“For my own “ part,” he adds, “I once believed this doctrine of ideas so firm“ly, as to embrace the whole of Berkeley's system in consequence “ of it; till finding some consequences to follow from it, which “gave me more uneasiness than the want of a material world, it “came into my mind, more than forty years ago, to put the “question, what evidence have I for this doctrine, that all the “objects of my knowledge are ideas in my own mind 2 From “that time to the present, I have been candidly and impartially, “as I think, seeking for the evidence of this principle, but can “find none, excepting the authority of philosophers.” We are told, in the life of Dr Berkeley, that, after the publication of his book, he had an interview with Dr Clarke ; in the course of which, Clarke discovered a manifest unwillingness to enter into the discussion about the existence of matter, and was accused by Berkeley of a want of candour.—The story has every appearance of truth; for as Clarke, in common with his antagonist, regarded the ideal theory as incontrovertible, it was perfectly impossible for him, with all his acuteness, to detect the flaw to which Berkeley's paradox owed its plausibility.
Note (G.) p. 117. In order to demonstrate the repugnance of the ideal theory to fact, Dr Reid observes, that, in its fundamental assumption, it confounds our sensations and perceptions together; * overlooking altogether the sensations by which the primary qualities of matter are made known to us. Berkeley says, that by the senses we have no knowledge but of our sensations only , and Locke, that
* Sensation properly expresses that change in the state of the mind, which is produced by an impression upon an organ of sense (of which change we can conceive the mind to be conscious, without any knowledge of external objects) : Perception, on the other hand, expresses the knowledge or the intimations we obtain, by means of our sensations, concerning the qualities of matter; and, consequently, involves, in every instance, the notion of eaternality or outness, which it is uecessary to exclude, as much as possible, from the thoughts, in order to seize the precise import of the word sensation.—See Outlines of Moral Philosophy, $14. (Edinburgh, 1808.) For a fuller illustration of this distinction, I must refer to Dr Reid. A clear conception of it (as he has himself emarked) is the key to all that be has written in opposition to the Berkeleian system. Priestley, through the whole of his strictures on Reid, studiously employs the two words as synonyInous terms,
**he primary qualities of body are resemblances of our sensa*itions, though the secondary are not. Now, upon this point we |alisimay venture to appeal to every man’s consciousness. Can any person doubt, that he has clear notions of extension and of figure, Pio which form the subjects of the proudest and most beautiful syshall stem of demonstrated truths yet brought to light by human reaindison 2 Indeed, what notions can be mentioned, more definite and be—"isatisfactory, than those which we possess, of these two qualities 2 triede And what resemblance can either bear to the changes which take Isamplace in the state of a sentient being 2 That we have notions of allows external qualities which have no resemblance to our sensations, saur, or to any thing of which the mind is conscious, is therefore a fact in to of which every man's experience affords the completest evidence; soroi and to which it is not possible to oppose a single objection, but on; its incompatibility with the common philosophical theories con|, or cerning the origin of our knowledge. * . The idea of Extension (without having recourse to any other) o, furnishes, of itself, an experimentum crucis for the determination is go of this question. The argument which it affords against the truth Dolio of the ideal theory is very forcibly stated by Dr Reid, in a pastura sage, the greater part of which I intended to have transcribed or here, in order to excite the curiosity of my readers with respect so to the work in which it is detailed at length. As I am preventmay ed, however, from doing so by want of room, I must request such on of them as have any relish for these speculations, to study with care the 5th and 6th sections of the 5th chapter of his Inquiry into the Human Mind; also the paragraph in the 7th section of the same chapter, beginning with the words, “This I would “ therefore humbly propose, as an experimentum crucis,” &c. * They are not to be comprehended fully without a considerable ... effort of patient reflection; but they are within the reach of any ... person of plain understanding, who will submit to this trouble; o and they lead to very important consequences in the philosophy o of the human mind. i. After the long interval which has elapsed since the first publication of this book, I should despair of reviving any degree of ... attention to the subject, if I did not recollect the opposition and * the neglect which all those truths have had, in the first instance, o to encounter, which are now regarded as the great pillars of mo
o tlern philosophy.-I was anxious, at the same time, to bring ino to immediate contrast the statement which was given by this auo thor, fifty years ago, of the incompatibility of our ideas of exten-* sion, figure, and motion, with the received systems concerning # the sources of our knowledge; and the indistinct pointings too wards the same conclusion, which have since appeared in the writ#" ings of Kant and others. The noise which this doctrine has made, o
in consequence of the mysterious veil under which they have disguised it, when compared with the public inattention to the simple and luminous reasonings of Reid, affords one of the most remarkable instances l know, of that weak admiration, which the half-learned are always ready to bestow on whatever they find themselves unable to comprehend. But on these and some collateral topics, I shall have an opportunity of explaining myself more fully in a subsequent note.
To those who take an interest in tracing the progress of philosophical speculation, it may not be unacceptable to know, that although Reid was indisputably the first who saw clearly the important consequences involved in the downfal of the ideal theory, yet various hints towards its refutation may be collected from earlier writers. So far from considering this anticipation as having any tendency to lower his merits, I wish to point it out to my readers, as a proof of the sagacity with which he perceived the various and extensive applications to be made of a conclusion, which, in the hands of his predecessors, was altogether sterile and useless. My own conviction, at the same time, is, that the passages I am now to quote, were either unknown to Dr Reid, or had altogether escaped his recollection, when he wrote his Inquiry. They exhibit, in fact, nothing more than momentary glimpses of the truth, afforded by some casual light which immediately disappeared, leaving the traveller to wander in the same darkness as before. The following sentence in Dr Hutcheson's Treatise on the Passions, considering the period at which the author wrote, reflects the highest honour on his metaphysical acuteness: “Extension, “figure, motion, and rest, seem to be more properly ideas ac“companying the sensations of sight and touch, than the sensa“tions of either of those senses.”—It does not appear, from any reference which he afterwards makes to this distinction, that he was at all aware of its value. The learned and judicious Crousaz, who wrote a little prior to Hutcheson, expresses himself nearly to the same purpose; and even dwells on the distinction at some length. In the following passage, I have taken no other liberty with the original, but that of suppressing some superfluous words and clauses, with which the author has loaded his statement, and obscured his meaning. The clauses, however, which I omit, and still more the preceding context, will satisfy any person who may take the trouble to examine them, that although he seems to have had Reid's fundamental principle fairly within his reach, he saw it too indistinctly to be able to trace its consequences, or even to convey its import very clearly to the minds of others. “When we would represent to ourselves something without us, ** and which resembles a sensation, it is evident that we pursue ** a mere chimera. A sensation can represent nothing but a sen** sation.: And sensation, being a species of thought, can repre** sent nothing which belongs to a subject incapable of thinking. ** It is not so with the objects of our perceptious. When I think “ of a tree or of a triangle, i know the objects, to which i give “ these names, to be different from my thoughts, and to have no ** resemblance to them.—The fact is wonderful, but it is not the ** less incontestible.” In Baxter's Treatise on the immateriality of the Soul, the same observation is not only repeated, but is employed expressly for the refutation of the Berkeleian system. It is, however, worthy of remark, that this ingenious writer has pushed his conclusion farther than he was warranted to do by his premises, aud, indeed, farther than his own argument required. “If our ideas have no parts, and yet if we perceive parts, it is “ plain we perceive something more than our own perceptions. ** But both these are certain : we are conscious that we perceive “ parts, when we look upon a house, a tree, a river, the dial“ plate of a clock or watch. This is a short and easy way of “being certain that something exists without the mind.”—(W. 11. p. 313.) It is evident, that the fact here stated furnishes no positive proof of the existence of external objects. It only destroys the force of Berkeley's reasonings against the possibility of their existence, by its obvious incompatibility with the fundamental principle on which all these reasonings proceed.—The inference, therefore, which Baxter ought to have drawn was this; that by our sensations we do receive notions of qualities which bear no resemblance to these sensations; and, consequently, that Berkeley's reasonings are good for nothing, being founded on a false hypothesis. This is precisely Reid's argument; and it is somewhat curious that Daxter, after having got possession of the premises, was not aware of the important consequences to which they lead. Of all the writers, however, who touched upon this subject, prior to the publication of Reid's Inquiry, none seems to have had a clearer perception of the truth, or to have expressed it with greater precision, than D'Alembert. “It is doubtless,” he observes in one passage, “ by the sense of touch we are enabled “to distinguish our own bodies from surrounding objects; but “how does it convey to us the notion of that continuity of parts “in which consists properly the notion of extension 2 Here is a “problem on which, it appears to me, that philosophy is able to “ throw a very imperfect light. In a word, the sensation by “means of which we arrive at the knowledge of ertention is, in “its nature, as incomprehensible as extension itself.”—(Elé
mens de la Philosophie, Article Métaphysique.) On a different occasion, the same writer has remarked, that, “as no relation “whatever can be discovered between a sensation in the mind, “ and the object by which it is occasioned, or at least to which “we refer it, there does not seem to be a possibility of tracing, “ by dint of reasoning, any practicable passage from the one “to the other.” And hence he is led to ascribe our belief of the existence of things external to “a species of instinct;”— “a principle,” he adds, “more sure in its operation than reason “itself.”—Disc. Prélim. de l'Encyclop.
In direct opposition to the fact which D'Alembert has thus not only admitted, but pointed out to his readers as involving a mystery not to be explained, it is astonishing to find him expressing, again and again, in different parts of his works, his complete acquit scence in Locke's doctrine, that all our ideas are derived from our sensations; and that it is impossible for us to think of any thing which has no resemblance to something previously known to us by our own consciousness. The remarks, accordingly, just quoted from him, are nowhere turned to any account in his subsequent reasonings.
All these passages reflect light on Reid's philosophy, and af. ford evidence, that the difficulty on which he has laid so great stress, with respect to the transition made by the mind from its sensations to a knowledge of the primary qualities of matter, is by no means (as Priestley and some others have asserted) the offspring of his own imagiuation. They prove, at the same time, that none of the authors from whom i have borrowed them, with the single exception of Baxter, have availed themselves of this difficulty to destroy the foundations of Berkeley’s scheme of lilealism ; and that Baxter himself was as unapprised as the others of the extensive applications of which it is susceptible to various other questions connected with the philosophy of the human mind. The celebrated Germau professor, Emanuel Kant, seems at last to have got a glimpse of this, notwithstanding the scholastic fog through which he delights to view every object to which he turns his attention. As his writings, however, were of a much later date than those of Dr Reid, they do not properly fall under our consideration in this note; and, at any rate, I must not now add to its length, by entering upon a topic of such extent and difficulty.
Note (H.) p. 117. The following strictures on Reid's reasonings against the ideal theory occur in a work published by Dr Priestley in 1774: “ Before our author had rested so much upon this argument, “it behoved him, I think, to have examined the strength of it “a little more carefully than he seems to have done; for he ap