« 上一頁繼續 »
ART. IV.-1. Lectures on the Philosophy of the Human Mind.
By Thomas Brown, M.D. 3 vols. 8vo. Philadelphia. 1824. 2. Inquiry into the Relation of Cause and Effect. By Thomas
BROWN, M. D. &c. 8vo. Andover. 1822.
Our readers may, perhaps, think it strange that we should at this late period invite their attention to the metaphysical writings of Dr. Brown. Our reasons are, that nothing more than their analysis has yet been given by the periodical press of our country; and that their value is as much too highly estimated by some, as underrated by others. It was to be expected, indeed, that works, treating of subjects which generally require close thinking, should be neglected by many who are unable or unwilling to yield them that application of mind which is necessary to their being understood; and there was equal reason for anticipating that the poetic language and ingenious argumentation of Dr. Brown, would beget an unbounded admiration in many of his readers, and cause them to receive without examination, whatever had the support of his name. That we shall be able to set the opinion of the public right on this subject, we have not the presumption to suppose; but we are willing to use our endeavours in attempting to moderate the applause of some; which, when so excessive, is seldom just : and to remove the prejudices of others, which prevent their approach to sources of real and extensive improvement.
We will make no apology, therefore, for introducing our readers at once into some of the most abstruse of Dr. Brown's speculations: and to those who hesitate to enter upon an article of metaphysics, we would address ourselves in the words of one of the fathers of the science :* “ Since it is the understanding that sets man above the rest of sensible beings, and gives bim all the advantage and dominion which he has over them, it is certainly a subject, even for its nobleness, worth our labour to inquire into.”
* Locke. If more ancient authority (and what would once have commanded more respect) be required, it may be given : “Tôv xadāv xai quíw Trv éidno iv υπολαμβάνοντες, μάλλον δ' εσέράν ετέρας, ή κατά ακρίβειαν, ή των βελτιόνων σε και θαυμασιωτέρων ειναι, δι' αμφότερα ταύτα σήν της κυχψης ιστορίαν ευλόγως αν εν πρώτοις τιθέιημεν. Δοκεί δε και προς αλήθειαν άπασαν η γνωσις αυτής μεγάλα oru Bannerdas."- Aristotelis de Anima, lib. i. Opera, tom.i. 166. Bas. 1531.
One of the most curious inquiries which can engage the attention of philosophers, is to ascertain the origin of our knowledge of a material world: and we may add, that it has proved to be one of the most difficult and perplexing. That the mind has a knowledge of material existences, and that this was obtained at a period earlier than is embraced by memory, must be admitted by all. But on the supposition of the mind's entire ignorance of the existence of the body, to which it has been so mysteriously united, and of its possessing only a susceptibility of feeling with certain fundamental principles of belief, of which the existence must have been coeval with that of the mind itself, it is no easy task to shew how the knowledge of external things could have been acquired. It is obvious that the senses are our only means of communication with things without; and of our senses, the investigation is soon confined to one as the only possible agent in the intercourse of mind and matter ; since the objects of sight, hearing, taste and smell are particles of matter so extremely minute as to be altogether imperceptible; and, consequently, could give us no notion of resistance and extension, the primary qualities of matter. Even though we knew the existence of these senses, therefore, they could not furnish us with any knowledge of the material causes of our sensations, however probable it may be that the very constitution of our nature would lead us to refer those feelings to causes. Our examination then may be liniited to the sense of touch ; and the question to be discussed is, whether the mind by the assistance of this sense, could arrive at the knowledge of the existence of matter.
Dr. Brown denies that the mind could make this acquisition in the circumstances described above; and supports his opinion in a very ingenious and forcible manner. The fallacy involved in the supposition that our notion of extension may be easily accounted for, by the similarity in figure of the compressed part of the organ of' touch to the compressing body, is exposed very fully, as an assumption of the point in dispute ;* and is further shown from the acknowledged fact in regard to the other organs of sense, that they induce in the mind no notion of figure, although it is certain that a determinate portion of these organs must be affected during sensation. The hypothesis that the notion of extension is connected immediately by our original constitution with the affections of the organs of touch—“the perception of a square arising immediately when the organ of touch is affected in a certain manner, as the sensation of the fragrance of a rose, arises immediately when the organ of smell is affected in a certain manner,” is thought to be very improba- . ble: for there should be no more indistinctness on this supposition in our perception of one figure than of another ;-of a figure of a thousand sides than of four; since the affection of the organ may be exactly conformed to the figure of the body.* This, however, is in opposition to constant experience. Touch then would be unable to inform the mind of extension. Nor would it be more useful in acquiring the notion of resistance : since this, according to Dr. Brown, is a consequence of muscular feelings, completely independent of the sensations of mere touch.t
* Vol. i. pp. 281-300.
+ pp. 282-301.
After rejecting the common belief as to the origin of our notions of extension and resistance, Dr. Brown proceeds to give his own theory in relation to this difficult inquiry. Tbis opinion is, that we arrive at the knowledge of material existence through the agency of certain muscular feelings that had been but little attended to by previous writers. The infant instinctively moves his arm in a certain manner; this motion is accompanied by a series of feelings in the mind : the movement is repeated, and the mind experiences the same series of feelings; and this happens perhaps a thousand times, so that the time occupied by the series of feelings is distinctly grasped by the mind. Now, if during one of these movements, something be opposed to the infant's arm, it will be conscious of the same volition on its part as before ; and at the same time will know that the series of feelings has been interrupted; and, ascending by an original law of mind from the effect to the cause, will conclude that there is something without itself, beyond its control. Thus, if we suppose the infant to have a certain series of feelings in consequence of his opening and closing his hand : when a hard body is placed on the palm of his hand, the closing of the hand will be prevented, and, therefore, the series of feelings will be broken: and as the infant had obtained a notion of the length of time necessary for the completion of the series of feelings, the length of the body will naturally be measured by that of the part of the series which had been prevented by the interposition of the body.ll 'Thus says Dr. Brown, length is first attributed to time; and afterwards to extension from the manner in which we obtain the notion of this property of matter. As yet, however, we have but one dimension of matter, length: the notion of breadth is acquired by the infant on discovering that a greater or less
# pp. 273-277.
* pp. 281-284-302-303.
+ p. 277.
vol. i. p. 309.
's Philosophy of the Human Mind
portion of the series of feelings is broken off. If only one finger be arrested by the interposed body, the notion of length is induced in the mind : if two or three fingers be resisted, the infant must have the notion of two or three co-existing lengths; and this, says Dr. Brown is breadth.*
We designed to have given Dr. Brown's theory in his own words, but found that this would occupy too much space: we have, therefore, contented ourselves with a careful abstract and frequent references to our author's pages, where our readers may examine for themselves the correctness of our condensed view of the theory. And, before proceeding farther, we must object to Dr. Brown's mode of expressing himself in relation to our notion of time, which performs so important a part in his speculations. This idea seems to have been drawn in from the necessity of obtaining some additional element in the formation of our notion of extension; and Dr. Brown appears not to have perceived very clearly that the origin of our idea of time was much more explicable than that of the extension which it was introduced to illustrate. He calls time, “our feeling of suc cession ;'!+ "our notions of succession ;"| "a series in constant and onward progress;" “remembered succession.”'s Now these expresssions are all very loose and vague; and instead of making more plain this new element involved in extension, cannot but render it more obscure; since they are absolutely false. Our notion of time is necessarily prior to our conception of succession ; otherwise we could not possibly conceive of things as successive. “To perceive this the more distinctly, let us call the distance between an idea and that which immediately succeeds it, one element of duration ; the distance between an idea and the second that succeeds it, two elements, and so on. If ten such elements make duration, then one must make duration, otherwise duration must be made up of parts that have no duration, which is impossible. Now it must be observed, that in these elements of duration, or single intervals of successive ideas, there is no succession of ideas, yet we must conceive them to have duration ; whence we may conclude with certainty, that there is a conception of duration, when there is no succession of ideas in the mind."|| Time then, which is measured duration, is an original notion of the mind, involved in succession and memory, but not derived from them. It would be less inaccurate to say, that succession and memory are derived from our notion of time, since without this, it would be impossible that we should have either.
* Vol. i. p. 310.
Ø p. 297. || Reid's Works, vol. ü. p. 35), on Intell, Powers, Ess. 3, c. 5.
Duration and space are most difficult to be grasped by the mind,* and seem to resemble each other in some particulars. Both are eternal, immoveable and unchangeable; and the progress which is attributed to time, is confined to ourselves. We are advancing in time as bodies are advancing in space; and the apparent motion of time is the natural consequence of our real progress. To the infinite mind, the whole of duration from eternity to eternity is one unchanging now. . Time appears to have the same relation to mind as space has to matter: bodies exist in space, but spirits in time: and it is as difficult to conceive how we could have thought without the notion of time, as how bodies could have moved without the previous existence of space.t The mind could not have existed one moment, without knowing that its existence had continued one moment, so that the knowledge of duration must have been possessed by the mind as soon as its existence commenced. So soon as it had existed in time, however short the period, this must have been known.
But to return to our author's theory: Dr. Brown thinks that an experiment which he has proposed, is almost decisive of his correctness in introducing time as an element in our notion of extension. “Let any one, with his eyes shut, move his hand with moderate velocity, along a part of a table, or any other hard smooth surface, the portion over which he passes will appear of a certain length; let him move his hand more rapidly, the portion of the surface pressed will appear less; let him move his hand very slowly, and the length, according to the degree of slowness, will appear increased in a most wonderful proportion."}
This experiment would be of considerable moment in the discussion, were it not that time as well as velocity enters into our estimation of the space passed over by a moving body: when we know the time and velocity, we obtain the exact space which has been traversed; when we know but one of the two elements, our estimate of the space must be formed from this alone. Thus, in the case adduced by Dr. Brown, we can form no accurate conception of the velocity because our eyes are shut, and, therefore, we measure the distance over which our hand has passed, by the known element, time: consequently, the distance should seem to be in proportion
* Not that there is any want of clearness in our conceptions of duration and space, but that in proportion as we attempt to view them more closely, they appear to elude our grasp. "Si non roges, intelligo."
+ The truth is visible under all the technical obscurity of Transcendentalism, which terms space and time forms of cognition, impressed by the mind upon the objects of its knowledge. The nineteenth century is not so favourable to the fame of founders of sects, as the age of Aristotle, in whose footsteps Kant seems desirons of walking, and from whom he has largely borrowed.
** Vol. p. 312. VOL. III.-N0. 5.