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

But even with regard to the mechanical affections of matter themselves, though all the changes which take place in nature were truly reducible to them, we should still have ultimately the same difficulty in attempting to predict, without experience, the changes that would ensue from them. The mechanical properties are indeed the most familiar to our thought, because they are those which we are constantly witnessing in the great displays of human power that are most striking to our senses. The house, the bridge, the carriage, the vessel, every implement which we use, and the whole wide surface of the cultivated earth, present to us, as it were, one universal trophy of the victories of the great mechanist, man. We cannot look back to the time when we were ignorant of the mechanical properties of matter; but still there was a time when they first became known to us, and became known by experience of the motions that resulted from them. What can be simpler than the phenomena of impulse? That a ball in motion, when it meets another at rest, should force this to quit its place, appears now to be something which it required no skill or experience to predict; and yet, though our faculties were, in every respect, as vigorous as now, – if we could imagine this most common of all phenomena to be wholly unknown to us, – what reason should we be able to discover in the circumstances that immediately precede the shock, for inferring the effect that truly results, rather than any other effect whatever? Were the laws of motion previously unknown, it would be in itself as presumable, that the moving ball should simply stop when it reached the other, or that it should merely rebound from it, as that the quiescent ball should be forced by it to quit its state of rest, and move forward in the same direction. We know, indeed, that the effect is different, but it is because we have witnessed it that we know it; not because the laws of motion, or any of the mechanical affections of matter whatever are qualities that might be inferred independently of observation.

Experience, then, is necessary in every case, for discovering the mutual tendencies of the elements of bodies, as much as for determining the reciprocal affections of the masses. But experience teaches us the past only, not the future, and the object of physical inquiry is, not the mere solitary fact of a change which has taken place, but the similar changes which will continually take place as often as the objects are again in the same circumstances, – not the phenomena only, but the powers by which the phenomena are produced.

Why is it, then, we believe that continual similarity of the future to the past, which constitutes, or at least is implied, in our notion of power? A stone tends to the earth, – a stone will always tend to the earth, – are not the same proposition; nor can the first be said to involve the second. It is not to experience, then, alone that we must have recourse for the origin of the belief, but to some other principle, which converts the simple facts of experience into a general expectation, or confidence, that is afterwards to be physically the guide of all our plans and actions.

This principle, since it cannot be derived from experience itself, which relates only to the past, must be an original principle of our nature. There is a tendency in the very constitution of the mind from which the expectation arises, – a tendency that, in every thing which it adds to the mere facts of experience, may truly be termed instinctive; for though that term is commonly supposed to imply something peculiarly mysterious, there is no more real mystery in it than in any of the simplest successions of thought, which are all, in like manner, the results of natural tendency of the mind to exist in certain states, after existing in certain other states. The belief is, a state or feeling of the mind as easily conceivable as any other state of it, – a new feeling, arising in certain circumstances as uniformly as in certain other circumstances. There arise other states or feelings of the mind, which we never consider as mysterious; those, for example, which we term the sensations of sweetness or of sound. To have our nerves of taste or hearing affected in a certain manner, is not, indeed, to taste or to hear, but it is immediately afterwards to have those particular sensations; and this merely because the mind was originally so constituted, as to exist directly in the one state after existing in the other. To observe, in like manner, a series of antecedents and consequents, is not, in the very feeling of the moment, to believe in the future similarity, but, in consequence of a similar original tendency, it is immediately afterwards to believe, that the same antecedents will invariably be followed by the same consequents. That this belief of the future is a state of mind very different from the mere perception or memory of the past, from which it flows, is indeed true; but what resemblance has sweetness, as a sensation of the mind, to the solution of a few particles of sugar on the tongue, – or the harmonies of music, to the vibration of particles of air? All which we know, in both cases, is, that these successions regularly take place; and in the regular successions of nature, which could not, in one instance more than in another, have been predicted without experience, nothing is mysterious, or every thing is mysterious. It is wonderful, indeed, – for what is not wonderful? – that any belief should arise as to a future which as yet has no existence; and which, therefore, cannot, in the strict sense of the word, be an object of our knowledge. But, when we consider Who it was who formed us, it would, in truth, have been more wonderful, if the mind had been so differently constituted that the belief had not arisen; because, in that case, the phenomena of nature, however regularly arranged, would have been arranged in vain, and that Almighty Being, who, by enabling us to foresee the physical events that are to arise, has enabled us to provide for them, would have left the creatures, for whom he has been so bounteously provident, to perish, ignorant and irresolute, amid elements that seemed waiting to obey them, – and victims of confusion, in the very midst of all the harmonies of the universe.

Mr Hume, indeed, has attempted to show, that the belief of the similarity of future sequences of events is reducible to the influence of custom, without the necessity of any intuitive expectation; but he has completely failed in the reasoning with which he has endeavoured to support this opinion. Custom may account for the mere suggestion of one object by another, as a part of a train of images, but not for that belief of future realities, which is a very different state of mind, and which, perhaps, does not follow every such suggestion, however frequent and habitual. The phenomenon A, a stone has a thousand times fallen to the earth; the phenomenon B, a stone will always, in the same circumstances, fall to the earth; are propositions that differ as much as the propositions, A, a stone has once fallen to the earth; B, a stone will always fall to the earth. At whatever link of the chain we begin, we must still meet with the same difficulty – the conversion of the past into the future. If it be absurd to make this conversion at one stage of inquiry, it is just as absurd to make it at any other stage; and, as far as our memory extends, there never was a time at which we did not make the instant conversion, – no period, however early, at which we were capable of knowing that a stone had fallen, and yet believed that, in exactly the same circumstances, there was no reason to suppose that it would fall again. But on this particular error of Mr Hume, the very narrow outline, within which the present sketch is necessarily bounded, will not permit me to enlarge. I have examined it, at considerable length, in the third edition of the Inquiry which I have published on the Relation of Cause and Effect.

It is more immediately our present purpose to consider, What it truly is which is the object of inquiry, when we examine the physical successions of events, in whatever manner the belief of their similarity of sequence may have arisen? Is it the mere series of regular antecedents and consequents themselves? or, Is it any thing more mysterious, which must be supposed to intervene and connect them by some invisible bondage?

We see, in nature, one event followed by another. The fall of a spark on gunpowder, for example, followed by the deflagration of the gunpowder; and, by a peculiar tendency of our constitution, which we must take for granted, whatever be our theory of power, we believe, that as long as all the circumstances continue the same, the sequence of events will continue the same; that the deflagration of gunpowder, for example, will be the invariable consequence of the fall of a spark on it; – in other words, we believe the gunpowder to be susceptible of deflagration on the application of a spark, – and a spark to have the power of deflagrating gunpowder.

There is nothing more, then, understood in the trains of events, however regular, than the regular order of antecedents and consequents which compose the train; and between which, if any thing else existed, it would itself be a part of the train. All that we mean, when we ascribe to one substance a susceptibility of being affected by another substance, is, that a certain change will uniformly take place in it when that other is present; – all that we mean, in like manner when we ascribe to one substance a power of affecting another substance, is, that, when it is present a certain change will uniformly take place in that other substance. Power, in short, is significant not of any thing different from the invariable antecedent itself, but of the mere invariableness of the order of its appearance in reference to some invariable consequent, – the invariable antecedent being denominated a cause, the invariable consequent an effect. To say, that water has the power of dissolving salt, and to say, that salt will always melt when water is poured upon it, are to say precisely the same thing; – there is nothing in the one proposition, which is not exactly, and to the same extent, enunciated in the other.

It would, indeed, be a very different theory of causation, if, without taking into account the important circumstance of invariableness or the uniform certainty of being at all times followed by a particular event, we were to say, that power is mere antecedence; for there can be no question, that phenomena precede other phenomena, which we never consider as having any permanent relation to them. They are regarded as antecedents, but not invariable antecedents, and the reason of this is obvious. Innumerable events are constantly taking place together in the immense system of the universe. There must, therefore, always be innumerable co-existing series, the parts of each of which, though permanently related to each other, may have no permanent relation to the parts of the other series; and one event of one series, may thus precede, not its own effect merely, which is to be its constant and uniform attendant, in all similar circumstances, but the events also of other co-existing series, which may never occur with it again at the same moment. There is no superstition in believing that an eclipse may be followed by a pestilence, or an unpleasant dream by some unforeseen calamity of the day, though there would be much superstition in believing, that these antecedents and consequents had any permanent relation to each other. In ordinary and familiar cases, at least, every one knows sufficiently the distinction of what is thus casual only, and what is invariable in the order of nature. Yet it is only by losing all sight of a distinction so very obvious, and confounding invariable with casual consequences, that Dr Reid, and other eminent philosophers, have been led into much laborious argumentation, in the confidence of confuting one of the simplest and justest of metaphysical opinions. To prove that power is more than invariable antecedence, they prove that it is more than casual antecedence, and that events do not follow each other, loosely and confusedly, as if antecedents could be invariable, which had not consequents as invariable, or, as if an uniform series were not merely another name for a number of uniform antecedents and consequents. A cause is, perhaps, not that which has merely once preceded an event; but we give the name to that which has always been followed by a certain event, is followed by a certain event, and according to our belief, will continue to be in future followed by that event, as its immediate consequent; and causation, power, or any other synonymous words which we may use, express nothing more than this permanent relation of that which has preceded to that which has followed. If this invariableness of succession, past, present, and future, be not that which constitutes one event the effect of another, Dr Reid, at least, has not pointed out any additional circumstance which we must combine with it, in our definition of an effect, though he has shown, indeed, with most abundant evidence, if any evidence at all were necessary, that the antecedents and consequents are not the same; that we use active and passive verbs, in different senses, applying, as might well be supposed, the one to the antecedent, the other to the consequent; that we speak of effects and causes as if truly different, since it is unquestionably not the same thing to follow uniformly a certain change, and to precede uniformly a certain change, and that we never think of giving those names where we do not conceive that there is some permanent relation. But, though these distinctions might be allowed to have irresistible weight, in opposition to the scepticism, if such extravagant scepticism there ever were, which affirmed the sequences of events to be altogether casual and irregular, they are surely of no weight against that simple definition of power, which affirms it to consist in the probability of the invariable sequence. of some event as its immediate consequent; since this very regularity of the sequences, which is supposed by the definition, must, of itself, have given occasion to all those distinctions of thought and language which Dr Reid has adduced.

That one event should invariably be followed by another event, is indeed, it will be allowed, as every thing in nature is, most wonderful, and can be ascribed only to the infinite source of every thing wonderful and sublime; the will of that divine Being, who gave the universe its laws, and who formed these with a most beneficent arrangement for the happiness of his creatures, who, without a belief in the uniformity of these laws, to direct their conduct, could not have known how to preserve even their animal existence. But the uniformity of succession is surely not rendered less wonderful, by a mere change of name. It is the same unaltered wonder still, when we ascribe the term power to the prior of two events, as when we ascribe to it the exactly synonymous phrase invariableness of antecedence; each of these terms implying nothing more than that the one event cannot take place without being immediately followed by the other. The permanence and uniformity of the relation are the essential circumstances. To be that which cannot exist, without being instantly followed by a certain event, is to be the cause of the event, as a correlative effect. It is impossible for us to believe, that the invariable antecedent is any thing but the cause, or the cause any thing but the invariable antecedent; as it is impossible for us to believe that homo is the Latin synonime of man, and yet that man is not the English synonime of homo.

To know the powers of nature, is, then, nothing more than to know what antecedents are and will be invariable, followed by what consequents; for this invariableness, and not any distinct existence, is all which the shorter term power, in any case, expresses; and this, and this alone, is the true object of physical inquiry, in that second point of view, in which we have considered it, as directed to the successions of events.

Whenever, therefore, the question is put, as to any object, What is it? there are two answers, and only two answers, that can be given with meaning. We may regard it as it exists in space, and state the elements that co-exist in it, or rather that constitute it; or we may regard it, as it exists in time, and state, in all the series of changes, of which it forms an invariable part, the objects to which it is related as antecedent or consequent.

To combine these two views of nature, as it exists in space and time, and to know, with perfect accuracy, every element of every aggregate, and every series of changes, of which each forms, or can form, a part, would be to know every thing which can be physically known of the universe. To extend our mere physical inquiry still farther into the phenomena of nature, after this perfect knowledge, would be to suppose erroneously, that, in the compounds before us, of which we know every element, there is some element, not yet discovered, or, in the well-known successions of events, some antecedent or consequent as yet unobserved; or it would be to inquire without any real object of inquiry, – a sort of investigation, which, for two thousand years, was almost the sole employment of the subtile and the studious, and which is far from having perished, with those venerable follies of the schools, at which we know so well how to smile, even while we are imitating them, perhaps, with similar errors of our own. I cannot but think, for example, that, on this very subject of the connexion of events, the prevalent notions and doctrines, even of very eminent philosophers, are not far advanced beyond the verbal complexity of the four causes of which Aristotle treats, the material, the formal, the efficient, and the final; or Plato's five causes, which Seneca, in one of his Epistles, briefly defines the id ex quo, the id a quo, the id quo, the id ad quod, and the id propter quod,26 and though there were no other evidence than this one subject affords, it would still, I fear, prove sufficiently, that, with all our manifest improvements in our plans of philosophical investigation, and all the splendid discoveries to which these improvements have led, we have not wholly lost that great art, which, for so long a time, supplied the place of the whole art of philosophizing – the art of inquiring assiduously, without knowing what we are inquiring about.

It is an art, indeed, which, there is too much reason to suppose, will accompany philosophy, though always, it is to be hoped, in less and less proportion, during the whole course of its progress. There will forever be points, on which those will reason ill, who may yet reason, with perfect accuracy, on other matters. With all those sublime discoveries of modern times, which do us so much honour, and with that improved art of discovery, which is still more valuable to us than the discoveries produced by it, we must not flatter ourselves with exemption from the errors of darker ages – of ages truly worthy of the name of dark, but to which we perhaps give the name, with more readiness, because it seems to imply, that our own is an age of light. Our real comfort, in comparing ourselves with the irrefragable and subtile doctors of other times, is not that we do not sometimes reason as indefatigably ill as they, and without knowing what we are truly reasoning about, but that we do this much less frequently, and are continually lessening the number of cases, in which we reason as ill, and increasing, in proportion, the number of cases, in which we reason better, and do truly know, what objects we are seeking.

Of all the cases, however, in which it is of importance, that the mind should have precise notions of its objects of inquiry, the most important are those which relate to the subject at present considered by us; because the nature of power, in the relation which it is impossible for us not to feel of events, as reciprocally effects and causes, must enter, in a great measure, into every inquiry which we are capable of making, as to the successive phenomena, either of matter or of mind. It is of so much importance, therefore, to our future inquiries, that you should know what this universal and paramount relation is, that I have dwelt on it at a length, which I fear must have already exhausted your patience; since it is a discussion, I must confess, which requires considerable effort of attention; and which has nothing, I must also confess, to recommend it, but its dry utility. I trust, however, that you are too well acquainted with the nature of science, not to know, that it is its utility which is its primary recommendation; and that you are too desirous of advancing in it, not to disregard the occasional ruggedness of a road, which is far from being always rugged. It may be allowed to him, who walks only for the pleasure of the moment, to turn away from every path, in which he has not flowers and verdure beneath his feet, and beauty wherever he looks around. But what should we have thought of the competitor of the Olympic course, whose object was the glory of a prize, contested by the proudest of his contemporary heroes, if, with that illustrious reward before him, – with strength and agility that might ensure him the possession of it, – and with all the assembled multitudes of Greece to witness his triumph, he had turned away, from the contest, and the victory, because he was not to tread on softness, and to be refreshed with fragrance, as he moved along! In that knowledge which awaits your studies, in the various sciences to which your attention may be turned, you have a much nobler prize before you; and, therefore, I shall not hesitate to call forth occasionally all the vigour of your attention, at the risk of a little temporary fatigue, as often as it shall appear to me, that, by exciting you to more than ordinary intellectual activity, I can facilitate your acquisition of a reward, which the listless exertions of the indolent never can obtain, and which is as truly the prize of strenuous effort, as the Palms of the Circus or the Course.

LECTURE VII

ON POWER, CAUSE, AND EFFECT

My last Lecture, Gentlemen, was chiefly employed in examining what it is, which is the real object of inquiry, when we consider the phenomena of nature as successive; and we found, that, by an original principle of our constitution, we are led, from the mere observation of change, to believe, that, when similar circumstances recur, the changes, which we observed, will also recur in the same order, – that there is hence conceived by us to be a permanent relation of one event, as invariably antecedent, to another event, as invariably consequent, – and that this permanent relation is all which constitutes power. It is a word, indeed, of much seeming mystery; but all which is supposed to be mysterious and perplexing in it vanishes, when it is regarded in its true light as only a short general term, expressive of invariable antecedence, or, in other words, of that, which cannot exist in certain circumstances, without being immediately followed by a certain definite event, which we denominate an effect, in reference to the antecedent, which we denominate a cause. To express, shortly, what appears to me to be the only intelligible meaning of the three most important words in physics, immediate invariable antecedence, is power, – the immediate invariable antecedent, in any sequence, is a cause, – the immediate invariable consequent is the correlative effect.

The object of philosophic inquiry, then, in that second department of it, which we considered with respect to the phenomena of nature as successive, we have found not to be any thing different from the phenomena themselves, but to be those very phenomena, as preceding or following, in certain regular series. Power is not any thing that can exist separately from a substance, but is merely the substance itself, considered in relation to another substance, – in the same manner, as what we denominate form, is not any thing separate from the elementary atoms of a mass, but is merely the relation of a number of atoms, as co-existing in apparent contact. The sculptor at every stroke of his chisel, alters the form of the block of marble on which he works, not by communicating to it any new qualities, but merely by separating from it a number of the corpuscles, which were formerly included by us, in our conception of the continuous whole; and when he has given the last delicate touches that finish the Jupiter, or the Venus, or Apollo, the divine form which we admire, as if it had assumed a new existence beneath the artist's hand, is still in itself unaltered, – the same quiescent mass, that slumbered for ages in the quarry of which it was a part.