Complete. From the essays on the “Intellectual Powers.”
BY the will of the Almighty Creator, all things in nature have been placed in certain relations to each other, which are fixed and uniform. In other words, they have been endowed with capacities of acting and capabilities of being acted upon, according to certain uniform laws; so that their actions take place in the same manner in every instance in which the same bodies are brought together under similar circumstances. We have a conviction, which appears to be original and instinctive, of the general uniformity of these relations; and in this consists our confidence in the regularity of all the operations of nature. But the powers or principles on which the relations depend are entirely hidden from us in our present state of being. The province of human knowledge is merely to observe the facts and to trace what their relations or sequences are. This is to be accomplished only by a careful and extensive observation of the facts as they pass before us, and by carefully distinguishing their true or uniform relations from connections which are only incidental and temporary.
In our first observation of any particular series of facts or events, we find a certain number of them placed together in a state of contiguity or apparent connection. But we are not entitled from this to assume the connection to be anything more than incidental juxtaposition. When, in the further progress of observation, we find the same events occurring a certain number of times, in the same relations or sequences to each other, we suspect that their connection is not merely that of incidental contiguity. We begin to believe that there exists among them such a relation as leads us, when we meet with some of these events, to expect that certain others are to follow. Hence is excited our idea of power in reference to these events, or of the relation of cause and effect. This relation, however, according to the utmost extent of our knowledge of it in any individual instance, is founded entirely upon the fact of certain events uniformly following one another. But when we have found, by sufficient observation, the particular events which do thus follow one another, we conclude that there is a connection, whatever may be the nature of it, in consequence of which the sequence which we have observed will continue to recur in the same fixed and uniform manner. In other words, we conclude with confidence that when we observe the first of two such events, the second will follow; and that when we observe the second, the first has preceded it. The first we call cause, the second effect. Thus our general confidence in the uniformity of the true relations or sequences of events is an original or instinctive principle, and not the result of experience; but it is by experience that we ascertain what the individual sequences are which observe this uniformity, or, in other words, learn to distinguish connections which consist of incidental contiguity from those which constitute true and uniform relations.
The natural tendency of the mind appears indeed to be to infer causation from every succession of phenomena and to expect uniformity in every sequence. It is from experience we learn that this impression is not to be relied on in regard to individual sequences, but requires to be corrected by observation. The result of our further experience then is to ascertain what those sequences or connections are which are uniform, and which, consequently, we may consider as connected in the manner of causation. We are thus first taught by experience the caution which is necessary in considering events as connected in the manner of cause and effect, and learn not to assume this relation till, by further experience, we have ascertained that the sequence is uniform. This caution, however, has no reference to our instinctive impression of causation, or our absolute conviction that every event must have an adequate cause; it only relates to our fixing the arrangement of individual antecedents, or, in other words, to our determining what individual events we are warranted in considering as the true antecedents or causes of certain other events. This, accordingly, can in many cases be accomplished only by long and extensive observation; while, in others, a single instance may be sufficient to produce an absolute conviction of what is the true antecedent. A child who has been only once burnt may dread the fire as certainly as if the accident had happened a hundred times; and there are many other instances in which the conviction may be produced in the same rapid manner. The natural tendency of the mind, in fact, is not only to infer the connection, but in many cases to carry it further than the truth. If, for instance, we suppose a man who, for the first time in his life, has seen gunpowder explode upon a match being applied to it, he would probably have an immediate conviction that a similar explosion would take place again in similar circumstances. But he would perhaps go further than this: he would probably expect a similar explosion when he applied a match to other black powders, with the nature of which he was unacquainted, such as powdered charcoal. It is by experience that this erroneous expectation would be corrected, and that he would learn the precise instances in which the particular result takes place. But it is also by experience that he learns the former, though the conviction was produced more immediately; for there is nothing in the character of gunpowder and charcoal from which any man could pronounce, by reasoning à priori, that the one would explode with violence when a match was applied to it and the other remain entirely unchanged.
Thus, our general impression of causation is not the result of experience, but an original and intuitive principle of belief; that is, our absolute conviction that every event must have an adequate cause. This is, in fact, that great and fundamental truth by which, from the properties of a known effect, we infer the powers and qualities of an unknown cause. It is in this manner, for example, that from the works of nature we infer the existence and the attributes of the Almighty Creator. But in judging of the connection between any two individual events in that order of things which he has established, our idea of causation is derived from experience alone; for, in regard to any two such events, our idea of causation or of power amounts to nothing more than our knowledge of the fact that the one is invariably the antecedent of the other. Of the mysterious agency on which the connection depends, we know nothing, and never can know anything in our present state of being. We know that the application of a match always sets fire to gunpowder, and we say that it has the power of doing so, or that it is the cause of the explosion; but we have not the least conception why the application of fire produces combustion in an inflammable substance;—these expressions, therefore, amount to nothing more than a statement of the fact that the result is universal.
When we speak, therefore, of physical causes, in regard to any of the phenomena of nature, we mean nothing more than the fact of a certain uniform connection which has been observed between events. Of efficient causes, or the manner in which the result takes place, we know nothing. In this sense, indeed, we may be said not to know the cause of anything, even of events which at first sight appear the most simple and obvious. Thus, the communication of motion from one body to another by impulse appears a very simple phenomenon,—but how little idea have we of the cause of it! We say the bodies touch each other, and so the motion is communicated. But, in the first place, we cannot say why a body in motion, coming in contact with one at rest, should put the latter in motion; and, further, we know that they do not come in contact. We may consider it, indeed, as ascertained that there is no such thing as the actual contact of bodies under these circumstances; and therefore the fact which appears so simple comes to be as unaccountable as any phenomenon in nature. What, again, appears more intelligible than an unsupported body falling to the ground? Yet what is more inexplicable than that one mass of matter should thus act upon another, at any distance, and even though a vacuum be interposed between them? The same observation will be seen to apply to all the facts which are most familiar to us. Why, for example, one medicine acts upon the stomach, another on the bowels, a third on the kidneys, a fourth on the skin, we have not the smallest conception; we know only the uniformity of the facts.
It is of importance to keep in mind the distinction now referred to between physical and efficient causes, as the former only are the proper objects of philosophical inquiry. The term final cause, again, has been applied to a subject entirely different; namely, to the appearances of unity of design in the phenomena of nature, and the manner in which means are adapted to particular ends. The subject is one of great and extensive importance, but it appears desirable that the name be altered, though it is sanctioned by high authority; for, when viewed in connection with the sense in which the word cause is employed in modern science, it expresses a meaning remarkably different. The investigation to which it refers is also of a distinct nature, though one of the highest interest. It leads us chiefly to the inductions of natural religion respecting a great and intelligent First Cause; but it may also be directed to the discovery of truth in regard to the phenomena of nature. One of the most remarkable examples of this last application of it is to be found in the manner in which Harvey was led to the discovery of the circulation of the blood, by observing the valves in the veins, and contemplating the uses to which their peculiar structure might be adapted.
The object of all science is to ascertain these established relations of things, or the tendency of certain events to be uniformly followed by certain other events; in other words, the aptitude of certain bodies to produce or to be followed by certain changes in other bodies in particular circumstances. The object of art is to avail ourselves of the knowledge thus acquired, by bringing bodies into such circumstances as are calculated to lead to those actions upon each other of which we have ascertained them to be capable. Art, therefore, or the production of certain results by the action of bodies upon each other, must be founded upon science, or a knowledge of their fixed and uniform relations and tendencies. This principle applies to all sciences, and to the arts or practical rules which are founded upon them; and the various sciences differ only in the particular substances or events which are their more immediate objects.
In the physical sciences, we investigate the relations of material substances, and their actions upon each other, either of a mechanical or chemical nature. On the relations thus ascertained are founded the mechanical and chemical arts, in which we produce certain results by bringing bodies into such circumstances as are calculated to give rise to their peculiar actions. But mental phenomena have also their relations, which are likewise fixed and uniform; though it may be more difficult to ascertain the truth in regard to them than in the relations of material things.
The relations or sequences of mental phenomena are to be considered in two points of view; namely, relations to each other, and relations to external things. In regard to both, it seems necessary to divide the phenomena themselves into three classes:
| 1. Simple intellect, or those powers by which we perceive, remember, and combine facts or events, and compare them with each other: such as perception, memory, imagination, and judgment. | |
| 2. Passive emotions, or those by which the mind is affected by certain pleasurable or painful feelings, which are, or may be, confined entirely to the individual who is the subject of them. | |
| 3. Active emotions, or those which tend directly to influence the conduct of men, either as moral and responsible beings, or as members of society. |
In all these classes mental phenomena have certain relations to each other and to external things, the investigation of which is the object of particular branches of science; and these lead to certain arts or practical rules which are founded upon them.
Intellectual science investigates the laws and relations of the processes of simple intellect, as perception, memory, imagination, and judgment; and the proper cultivation and regulation of these is the object of the practical art of intellectual education.
The passive emotions may be influenced or excited in two ways; namely, through our relations to other sentient and intelligent beings, and by material or inanimate things. To the former head are referable many of the tenderest and most interesting feelings of our nature, as love, hope, joy, and sorrow. To the latter belong those emotions which come under the subject of taste, or the tendencies of certain combinations of material things to excite emotions of a pleasurable or painful kind,—as our impressions of the sublime, the beautiful, the terrible, or the ludicrous. The practical rules or processes connected with the science of the passive emotions arrange themselves into two classes, corresponding to the two divisions now mentioned. To the former belong the regulation of the emotions, and all those rules of conduct not exactly referable to the higher subject of morals, which bear an extensive influence on the ties of friendship—and the relations of social and domestic intercourse. To the latter belong chiefly those processes which come under the head of the fine arts; namely, the arts of the painter, the sculptor, the architect, the musician,—perhaps we may add, the poet and the dramatist.
The active emotions, or those which influence human conduct, are referable to two classes; namely, those which affect men individually as moral and responsible agents, and those which affect them as united in large bodies constituting civil society. The cultivation of the emotions of the former class, and the investigation of the motives and principles by which they are influenced, belong to the high subjects of morals and religion. The investigation and control of emotions of the latter class come under the science of politics; and the practical art, founded upon it, relates to those measures by which the statesman attempts to control and regulate the conduct of masses of mankind united as members of a great civil community.
In medical science the objects of our researches are chiefly the relations between external things and the living powers of animal bodies,—and the relations of these powers to each other;—more particularly in regard to the tendencies of external things to produce certain changes upon living bodies, either as causes of disease or as remedies. The practical art founded upon this science leads to the consideration of the means by which we may avail ourselves of this knowledge, by producing, in the one case, actions upon the body which we wish to produce, and in the other, by counteracting or avoiding actions which we wish to prevent.
In all these sciences, and the practical arts which are founded upon them, the general principles are the same; namely, a careful observation of the natural and uniform relations or tendencies of bodies towards each other, and a bringing of those tendencies into operation for the production of results. All art, therefore, must be founded upon science, or a correct knowledge of these relations; and all science must consist of such a careful observation of facts in regard to the relations, as shall enable us confidently to pronounce upon those which are fixed and uniform. He who follows certain arts or practical rules, without a knowledge of the science on which they are founded, is the mere artisan or the empiric; he cannot advance beyond the precise rules which are given him, or provide for new occurrences and unforeseen difficulties. In regard to science, again, when the relations are assumed hastily, or without a sufficiently extensive observation of facts, the process constitutes false science, or false induction; and when practical rules are founded upon such conclusions, they lead to error and disappointment in the result expected.
The views which have now been referred to lead us to principles by which the sciences are distinguished into those which are certain and those which are, in a greater or less degree, uncertain. The certainty of a science depends upon the facility and correctness with which we ascertain the true relations of things, or trace effects to their true causes, and causes to their true effects,—and calculate upon the actions which arise out of these relations taking place with perfect uniformity. This certainty we easily attain in the purely physical sciences, or those in which we have to deal only with inanimate matter. For in our investigation of the relations of material bodies, whether mechanical or chemical, we contrive experiments, in which by placing the bodies in a variety of circumstances towards each other, and excluding all extraneous influence, we come to determine their tendencies with perfect certainty. Having done so, we rely with confidence on these tendencies continuing to be uniform; and should we in any instance be disappointed of the result which we wish to produce, we are able at once to detect the nature of some incidental cause by which the result has been prevented, and to obviate the effect of its interference. The consequence of this accurate knowledge of their relations is, that we acquire a power over material things; but this power is entirely limited to a certain control and direction of their natural relations; and we cannot change these relations in the smallest particular. Our power is of course also limited to those objects which are within the reach of our immediate influence; but with respect to those which are beyond this influence, as the heavenly bodies, the result of our knowledge appears in a manner not less striking, in the minute accuracy with which we are enabled to foretell their movements, even at very distant periods. I need only mention the correctness with which the astronomer calculates eclipses and the appearance of comets.
With these characters of certainty in the purely physical sciences, two sources of uncertainty are contrasted in those branches of science in which we have to deal with mental operations, or with the powers of living bodies. The first of these depends upon the circumstance, that, in investigating the relations and tendencies in these cases, we are generally obliged to trust to observation alone, as the phenomena happen to be presented to us, and cannot confirm or correct these observations by direct experiment. And as the actual connections in which the phenomena occur to us are often very different from their true relations, it is in many cases extremely difficult to ascertain the true relations, that is, to refer effects to their true causes and to trace causes to their true effects. Hence just conclusions are arrived at slowly, and after a long course of occasional observations; and we may be obliged to go on for a long time without acquiring any conclusions which we feel to be worthy of confidence. In these sciences, therefore, there is great temptation to grasp at premature inductions; and when such have been brought forward with confidence, there is often difficulty in exposing their fallacy; for in such a case it may happen that as long a course of observation is required for exposing the false conclusion as for ascertaining the true. In physical science, on the other hand, a single experiment may often overturn the most plausible hypothesis, or may establish one which was proposed in conjecture.
The second source of uncertainty in this class of sciences consists in the fact that, even after we have ascertained the true relations of things, we may be disappointed of the results which we wish to produce, when we bring their tendencies into operation. This arises from the interposition of other causes, by which the true tendencies are modified or counteracted, and the operation of which we are not able either to calculate upon or to control. The new causes, which operate in this manner, are chiefly certain powers in living animal bodies, and the wills, feelings, and propensities of masses of human beings, which we have not the means of reducing to any fixed or uniform laws. As examples of the uncertain sciences, therefore, we may mention medicine and political economy; and their uncertainty is referable to the same sources, namely, the difficulty of ascertaining the true relations of things, or of tracing effects to their true causes, and causes to their true effects;—and the intervention of new causes which elude our observation, while they interfere with the natural tendencies of things, and defeat our attempts to produce certain results by bringing these into action. The scientific physician well knows the difficulty of ascertaining the true relations of those things which are the proper objects of his attention, and the uncertainty which attends all his efforts to produce particular results. A person, for example, affected with a disease recovers under the use of a particular remedy; a second is affected with the same disease, and uses this remedy without any benefit; while a third recovers under a very different remedy, or without any treatment at all. And even in those cases in which he has distinctly ascertained true relations, new causes intervene and disappoint his endeavors to produce results by means of these relations. He knows, for example, a disease which would certainly be relieved by the full operation of diuretics, and he knows various substances which have unquestionably diuretic virtues. But in a particular instance he may fail entirely in relieving the disease by the most assiduous use of these remedies, for the real and true tendencies of these bodies are interrupted by certain other causes in the constitution itself, which entirely elude his observation and are in no degree under his control.
It is unnecessary to point out the similarity of these facts to the uncertainty experienced by the statesman in his attempts to influence the interests, the propensities, and the actions of masses of mankind; or to show how often measures which have been planned with every effort of human wisdom fail of the results which they were intended to produce, or are followed by consequences remarkably different. Nothing indeed can show in a more striking manner the uncertainty which attaches to this science than the different aspects in which the same measure is often viewed by different men distinguished for political wisdom and talent. I abstain from alluding to particular examples, but those accustomed to attend to public affairs will find little difficulty in fixing upon remarkable instances in which measures have been recommended by wise and able men, as calculated to lead to important benefits, while others of no inferior name for talent and wisdom have, with equal confidence, predicted from them consequences altogether different. Such are the difficulties of tracing effects to their true causes, and causes to their true effects, when we have to deal, not with material substances simply, but with the powers of living bodies, or with the wills, the interests, and the propensities of human beings.
