Little Masterpieces of Science: Mind

by Unknown

COMMON SENSE

WILLIAM BOYD CARPENTER, M.D.

[Dr. Carpenter was one of the leading men of science in the generation which has recently passed away. He was a physician and psychologist of mark, and withal a geographer of erudition and extensive travel. His famous work, “Principles of Mental Physiology,” is published by D. Appleton & Co., New York. Its eleventh chapter, minus a few paragraphs, is here presented.]

There are two principal forms of common sense which it is desirable clearly to distinguish. The first is what the philosopher means by common sense, when he attributes to it the formation of those original convictions or ultimate beliefs, which cannot be resolved into simpler elements, and which are accepted by every normally constituted human being as direct cognitions of his own mental states. It might, indeed, be maintained that this necessary acceptance of propositions which only need to be intelligibly stated to command unhesitating and universal assent, cannot rightly be termed an act of judgment. But just as sense-perceptions, which are intuitive in the lower animals, have been acquired in man by a process of self-education in the earliest stages, in which acts of judgment are continually called for, so may we regard the autocratic deliverances of the universal common sense of mankind as really having, in the first instance, the characters of true judgments, each expressing the general resultant of uniform experience,—which may be partly of the individual, and partly that of the race embodied in the constitution of each member of it.

The second or popular acceptance of the term common sense, on the other hand, is that of an attribute which judges of things whose self-evidence is not equally apparent to every individual, but presents itself to different individuals in very different degrees, according in part to the original constitution of each, and in part to the range of his experience and degree in which he has profited by it. This is the form of common sense by which we are mainly guided in the ordinary affairs of life: but inasmuch as we no longer find its deliverances in uniform accordance, but encounter continual divergences of judgment as to what things are self-evident,—some being so to A whilst they are not so to B, and others being self-evident to B which are not so to A,—it cannot be trusted as an autocratic or infallible authority. And yet, as Dr. Reid truly says, “disputes very often terminate in an appeal to common sense;” this being especially the case, when to doubt its judgment would be ridiculous.

If the view here taken be correct, these two forms—which may be designated respectively as elementary and as ordinary common sense—have fundamentally the same basis; and we may further connect with them as having a similar genesis, those special forms of common sense, which are the attributes of such as have applied themselves in a scientific spirit to any particular course of inquiry,—things coming to be perfectly self-evident to men of such special culture, which ordinary men, or men whose special culture has lain in a different direction, do not apprehend as such.

The judgment of common sense as to any self-evident truth, may be defined as the immediate or instinctive response that is given (in psychological language) by the automatic action of the mind, or (in physiological language) by the reflex-action of the brain to any question which can be answered by such a direct appeal. The nature and value of that response will depend upon the acquired condition of the mind, or of the brain, at the time it is given; that condition being the general resultant of the whole psychical activity of the individual. The particular form of that activity is determined, as we have seen, in the first place, by his original constitution; secondly, by the influences which have been early brought to bear upon it from without; and thirdly, by his own power of self-direction. And it may be said that while the elementary form of common sense depends mainly upon the first of these factors, its ordinary form chiefly arises out of the first and second, and its special forms almost exclusively out of the third;—the response being given, in each case, by a nervous mechanism, in the organization of which the generalized results of the past experiences of consciousness (whether of the race or of the individual) have become embodied.

The parallel between the cerebral action which furnishes the mechanism of thought now under consideration, and the action of the sensori-motor apparatus which furnishes the mechanism of sense and motion, is extremely close. We have seen that there are certain sense-perceptions, which, although not absolutely intuitive, very early come to possess—in every normally constituted human being—the immediateness and perfection of those corresponding perceptions which are intuitive in the lower animals; and that with these are associated certain respondent motions, which, though acquired by practice in the first instance, ultimately come to be performed as by a second nature. Certain of these motions, such as walking erect, are universally acquired; and thus obviously come to be the expressions of the original endowments of the mechanism, trained by an experience very similar in the uniformity of its character to that which educates the elementary form of common sense. For it must be clear to any one who compares the erect progression of a child who has just learned to walk, with that of a dancing dog or even of a chimpanzee, that while experience makes its acquirement possible in each case, only an organism which is at the same time structurally adapted for erect progression and possessed of a special co-ordinating faculty, can turn such experience to full account. The balancing the body in the erect position at starting, the maintenance of that balance by a new adjustment of the centre of gravity as the base of support is shifted from side to side and from behind forwards, and the alternate lifting and advance of the legs, involve the harmonious co-operation of almost all the muscles in the body. Although this co-operation is brought about in the first instance by the purposive direction of our efforts towards a given end, under the guidance of our visual and muscular sensations, yet when we have once learned to walk erect, we find ourselves able to maintain our balance without any exertion of which we are conscious; all that is necessary for the performance of this movement being that a certain stimulus (volitional, or some other) shall call the mechanism into activity.—But further, we have seen that special powers of sense-perception can be acquired by the habitual direction of the attention to particular classes of objects; and that special movements come to be the secondarily automatic expression of them. How nearly related these are to the preceding, we may assure ourselves by attending to the process by which an adult learns to walk on a narrow base, such as a rope or the edge of a plank. For the co-ordinating action has here to be gone through afresh under altered and more special conditions, so as to give a greater development to the balancing power; yet when this has been fully acquired, it is exerted automatically with such an immediateness and perfection, that a Blondin can cross Niagara on his rope with no more danger of falling into the torrent beneath, than any ordinary man would experience if walking without side-rails along the broad platform of the suspension bridge which spans it. Now since in those cases in which man acquires powers that are original or intuitive in the lower animals, there is the strongest reason for believing that a mechanism forms itself in him which is equivalent to that congenitally possessed by them, we seem fully justified in the belief that in those more special forms of activity which are the result of prolonged training, the sensori-motor apparatus grows to the mode in which it is habitually exercised, so as to become fit for the immediate execution of the mandate it receives: it being often found to act not only without intelligent direction, but without any consciousness of exertion, in immediate response to some particular kind of stimulus,—just as an automaton that executes one motion when a certain spring is touched, will execute a very different one when set going in some other way.

There is strong analogical ground, then, for the belief that the higher part of the nervous mechanism which is concerned in psychical action, will follow the same law; embodying the generalized result of its experiences, so as to become able to evolve, by a direct response, a result of which the attainment originally required the intervention of the conscious mind at several intermediate stages of the process. What there is strong ground for believing in regard to the perceptional consciousness, may fairly be extended to the ideational, which is so intimately connected to it, the unconscious co-ordinating action, which in the former case brings the whole experience to bear upon the question, whilst the decisions of the latter are based upon a limited, and therefore one-sided, view of it,—the defect of judgment being due either to an original want of the co-ordinating power, or to disuse of the exercise of it through the limitation of the attention to special fields of study. It may often be noticed that children display a power of bringing common sense to bear upon the ordinary affairs of life, which seems much beyond that of their elders; and yet a very sensible child will often grow into a much less sensible man. Now the reason of this seems to be, that the child perceives the application of self-evident considerations to the case at issue, without being embarrassed by a number of other considerations (perhaps of a trivial or conventional nature) which distract the attention and unduly influence the judgment of the adult. And the deliverances of a child's common sense thus often resemble those of the old court fools, or jesters, whose function seems to have been to speak out home truths which timid courtiers would not venture to utter. Moreover, as has been well remarked, “it is quite possible for minds of limited power to manage a small range of experience much better than a large, to get confused (as it were) with resources on too great a scale, and therefore to show far more common sense within the comparatively limited field of childish experience, than in the greater world of society or public life. This is probably the explanation of a thing often seen,—how very sagacious people instinctively shrink from a field which their tact tells them is too large for them to manage, and keep to one where they are really supreme.”