« ΠροηγούμενηΣυνέχεια »
philosopher down to that of the most ignorant peasant; but as it is not possible, on his principles, to account for the generation of that idea, he is willing to regard it as nothing more than an illusion. Proceeding on the theory of perception transmitted from the ancient schools to Descartes and Locke, he remarks, that "it seems a proposition which will not admit of much dispute, that all our ideas are nothing but copies of our impressions, or in other words, that it is impossible for us to think of any thing which we have not antecedently felt, either by our external or internal senses.-To be fully acquainted, therefore, with the idea of power or necessary connection, let us examine its impression; and in order to find the impression with greater certainty, let us search for it in all the sources from which it may possibly be derived.When we look about us towards external objects, and consider the operation of causes, we are never able, in a single instance, to discover any power or necessary connection, any quality which binds the effect to the cause, and renders the one an infallible consequence of the other. We only find that the one does actually in fact follow the other. The impulse of one billiard ball is attended with motion in the second. This is the whole that appears to the outward senses. The mind feels no sentiment or inward impression from this succession of objects: consequently, there is not, in any single particular instance of cause and effect, any thing which can suggest the idea of power or necessary connection.' He concludes by stating "We have sought in vain for an idea of power or necessary connection, in all the sources from which we could sup
pose it to be derived. It appears that in single instances of the operation of bodies, we never can, by our utmost scrutiny, discover any thing but one event following another; without being able to comprehend any force or power by which the cause operates, or any connection between it and its supposed effect. The same difficulty occurs in contemplating the operations of mind or body, where we observe the motion of the latter to follow upon the volition of the former; but are not able to observe or conceive the tie which binds together the motion and volition, or the energy, by which the mind produces this effect. The authority of the will over its own faculties and ideas, is not a whit more comprehensible: so that upon the whole, there appears not throughout all nature, any one instance of connection which is conceivable by us. All events seem entirely loose and separate. One event follows another, but we never can observe any tie between them. They seem conjoined but never connected. But as we have no idea of any thing, which never appeared to our outward sense or inward sentiment, the necessary conclusion seems to be, that we have no idea of connection or power at all, and that these
words are absolutely without any meaning, when employed either in philosophical reasonings or common life."
This reasoning viewed in relation to Mr. Hume's doctrines on the generation of ideas, is perfectly logical and conclusive. The idea of power not being derivable from any of the qualities of matter, primary or secondary, nor from the exercise of reason on any of our external or internal impressions, it followed naturally, according to the principles of the school in which he had learned his philosophy, that we have no such idea at all, and that the word expressive of it has, in fact, no meaning, either in scientific or popular language. The best and the shortest answer, therefore, that can be given to every conclusion founded on such principles, is to assert, that we find ourselves in possession of simple ideas, and fundamental laws of belief, which cannot be traced to either of the two sources from which Mr. Hume, after the example of Locke and Descartes, undertook to derive all the elements of human knowledge. We are so constituted that every effect we contemplate, not only suggests the existence of a cause, but also that quality in the cause which is usually described by the words efficiency and power: that is, we instantly attribute to the antecedent a property analogous to the character of the consequent, and measure the nature and extent of the former, by the phenomena which present themselves in the latter.
Dr. Brown in his "Inquiry into the relation of Cause and Effect" differs ostensibly from Mr. Hume, while, in fact, he conducts his examination on the same principles, and arrives nearly at the same conclusion.
"A cause," says he, " in the fullest definition which it philosophically admits, may be said to be, that which immediately precedes any change, and which existing at any time in similar circumstances, has been always, and will be always, immediately followed by a similar change. Priority in the sequence observed, and invariableness of antecedence in the part of future sequences supposed, are the elements, and the only elements, combined in the notion of a cause. By a conversion of terms, we obtain a definition of the correlative effect; and power is only another word for expressing abstractly and briefly the antecedence itself, and the invariableness of the relation.-It is this mere relation of uniform antecedence, so important and so universally believed, which appears to me to constitute all that can be philosophically meant in the words power or causation, to whatever objects material or spiritual, the words may be applied."
It is obvious that this is a mere description of certain circumstances attending causation, and that the author tacitly admits the conclusion of Hume in regard to the impossibility of forming any idea of power. The relation of cause and effect is resolved
into the constant and invariable sequence of two events. We are thereby presented only with the occasion on which our perception or belief of the relation is produced; but as to the nature of the relation itself, it follows that we know nothing, and cannot even form the most remote conception. That there is in the cause or antecedent the quality or power of producing the effect, is an inference which forces itself upon our understanding; but this inference when strictly analyzed amounts, perhaps, to nothing more than to the constant and invariable sequence which has been already mentioned.
Power, according to Dr. Brown, may receive exactly the same definition as property or quality; all the three expressing only a certain relation of invariable antecedence and consequence, in changes that take place on the presence of the substance to which they are ascribed. Power, property, quality, are, when employed in relation to physics, strictly synonymous. Water has the power of melting salt: it is the property of water to melt salt: it is a quality of water to melt salt-all these varieties of expression, says he, signify precisely the same thing,-that when water is poured upon salt, the solid will take the form of a liquid, and its particles be diffused in continued combination through the mass. Two parts of a sequence of physical events are before our mind; the addition of water to salt, and the consequent liquefaction of what was before a crystalline solid.-The powers, properties, or qualities of a substance, are not to be regarded then, he continues, as any thing superadded to the substance or distinct from it. They are only the substance itself considered in relation to various changes that take place when it exists in peculiar circumstances. The qualities of substances, he repeats in another place, however we may seem verbally to regard them, are separate or separable, are truly the substances themselves, considered by us together with other substances, in which a change of some sort is consequent on the introduction of them. These are not substances, therefore, and also powers and qualities, but substances alone. The sensible qualities, therefore, whatever they may be, and with whatever names we may distinguish them, denote nothing more than the uniform relation of antecedence of certain external objects to certain feelings which are their consequents.
We must acknowledge that, when the term power is used as synonymous with quality and property, the relation of cause and effect appears considerably simplified; for as we cannot in any instance separate the quality from the substance, even by an effort of abstraction, we see more clearly the reason why we cannot form the idea of power, except in so far as it may be resolved into the invariable sequence of one event upon the appearance of
another, with which it has always been connected. We seem somehow to have got quit of the mysticism which has been thrown around the word power, and to have found a resting-place for our imagination in the less complicated idea of an ordinary property belonging to an ordinary substance: and no circumstance, perhaps, could prove more strikingly that we had never attained any precise notion respecting cause and effect, than the discovery we have just made, namely, that a different word may be substituted for the one to which our supposed idea has usually been attached, and serve equally well to denote the metaphysical relation which that other had been employed to express.
It is true, then, that though by the very constitution of our minds we are led to infer from every effect we contemplate the existence of an adequate cause, we have not in reality any idea of power in a strictly physical sense; that is, in the two natural events which we denominate cause and effect, we perceive nothing besides constant and invariable sequence; nothing in the former that must necessarily produce the other. Our knowledge of causation is not derived from the argument a priori; nor even after experience in the most familiar cases, is that relation discovered by any process of reasoning; but it is, in all cases, the object of intuitive belief; an inference which forces itself upon us, so soon as we have exercised our intellectual faculties on the phenomena of the material universe. It is, therefore, perfectly correct to say that we have the belief of power or efficiency, but that we have no idea of either; a distinction which applies to much of that mixed knowledge, inference, and intuition, which constitute the furniture of our minds.
This distinction, however, has not been admitted by the author of Dr. Brown's life, who thinks it necessary to defend the Professor against a charge adduced by some of his antagonists, "that he denied there is such a thing as power, or that we have any idea of efficiency." Dr. Brown does not, indeed, deny that there is such a thing as power, but he does most assuredly deny that we have any idea of efficiency. Not perceiving the difference between believing that a thing or quality exists, and the having a conception of that thing or quality, the biographer proceeds to give an explanation of Dr. Brown's opinions, which, in fact merely strengthens the ground on which the charge was originally made to rest :—
"I am convinced," says he, "that nothing more is necessary than to refer the reader to the extracts I have already made from Dr. Brown's work, to show that the charge is entirely without foundation. He does certainly maintain that power is nothing more than invariableness of antecedence; but then in the course of his work, he states, again and again, in many varied forms of ex
pression, that the very first time we see a sequence of events, we believe that in all similar circumstances, the same antecedent will be followed by the same consequent; that we believe this by intuition; that it is impossible for us not to believe it. Nay, he says in express words, that the mind is originally led to believe causation in every sequence. It is vain to say, if this be Dr. Brown's doctrine, wherein does it differ from what every other writer maintains upon the subject? that has nothing to do with the present question. That question is whether he did or did not admit of the existence of power, and of the idea of power? If he did not, then, with all the love I bear his memory, I should rejoice to aid in the prompt exclusion of so monstrous a heresy." Mr. Welsh even goes so far as to maintain that, "it is altogether unjust to accuse Mr. Hume himself of denying the idea of power. In the 'Essay on Necessary Connection,' Mr. Hume certainly does state as clearly as language can express that we have an idea of necessary connection. Dr. Reid was the first who represented him as maintaining the opposite doctrine; and his views, I presume, have been copied by the writers who followed him, without their putting themselves to the trouble of consulting Mr. Hume's writings for themselves."
We are amazed at the ignorance which pervades the whole of this statement, in regard to fact as well as to reasoning. Mr. Hume does most assuredly deny that we have an idea of necessary connection, and Dr. Reid did not by any means misrepresent the doctrines of that author, when he ascribed to him the opinion now mentioned. After giving two definitions of a cause, Mr. Hume, in the second section of his essay, proceeds to remark that "though both these definitions be drawn from circumstances foreign to the cause, we cannot remedy this inconvenience, or attain any more perfect definition which may point out that circumstance in the cause which gives it a connection with the effect. WE HAVE NO IDEA OF THIS CONNECTION; nor even any distinct notion what it is we desire to know, when we endeavour at a conception of it. We say, for instance, that the vibration of this string is the cause of this particular sound. But what do we mean by that affirmation? We either mean that this vibration is followed by this sound, and that all similar vibrations have been followed by similar sounds: or, that this vibration is followed by this sound, and that upon the appearance of one, the mind anticipates the senses, and forms immediately an idea of the other. We may consider the relation of cause and effect in either of these two lights; but beyond these we have no idea of it.
Neither Hume, nor his pupil Dr. Brown, denies the existence of