Strictly speaking, we cannot apply quantitative conceptions to consciousness, inasmuch as mind has no spatiality which is the basis of idea of quantity and size. Hence the use of quantitative terms, like great, large, small, little, etc., is an indirect reference to intensity. I was in very great pain equals I was in very intense pain. No consciousness is literally either larger or smaller than another, because consciousnesses cannot, by reason of their non-spatial nature, enter into quantitative relations. So-called massive pains are really manifold. (See on this and kindred points my remarks in Nature, vol. 40, p. 642.)
A popular test of mental intensity, and one which has a relative value, is by the power needed to displace a given psychosis. Thus, if a man in a brown study walks into a pond of cold water without noticing it, we rightly conclude that he is thinking very intensely. This, of course establishes a scale relative to the individual, beginning with a psychosis which resists all displacing agencies, and ending with those of such very slight intensity that they give way to any and all diversions. A consciousness which supplants another must per se be more intense than the other. All that which rouses and diverts patients suffering from monomania and fixed ideas is practically equal in intensity. While we may thus pronounce one state as being equal in intensity to another or as being more or less intense than it, we yet have no ground for any numerical estimate. When a person says, “I feel twice as bad as I did yesterday, or I feel a hundred times as happy now as I was a year ago,” it is plainly a general and indefinite expression. Emotions have not yet been brought within the range of mathematical comparisons.
The intensity of feelings, as also of sensations, sustains undoubtedly certain mathematical relations to intensity of objective stimulus, but owing to their complex nature, emotions, at least, must always be very difficult of interpretation by any such law as Weber’s, though simple pain may be brought more easily under some law. A pain, other things being equal, increases in some ratio to increment of physical stimulus. But we must believe that the reason for the diversity between proportion of actual increments of stimulus and actual increments of sensation and feeling is largely physiological. It certainly is not a true psycho-physical law, a law of relation of mind and matter, as is often claimed; for we cannot obtain an absolutely objective standard to test subjectivity. Hence any such law is merely a law of relation of different kinds of sensations, of different methods of interpreting the objective. Intensity of stimulus itself is always determinable only through some sensation, which is itself subject to Weber’s law. There is no objective standard for sense stimuli; the measure of increasing stimulus to increasing sensation must be by some sense which has its own law with reference to physical increment as interpreted by another sense equally under law, and so on. Take pressure, for instance; we note by sense of sight the arm of a balance reacting regularly and constantly to definite small additions to load, while upon our own arm we do not notice the same additions in any such series of feeling of pressure increments. The arm and balance as disparate weighers must, of course, be in certain ratios related, and for a certain range we must have a geometrical series, but other ratios at other points.
That the degree of sensitivity is proportioned to the intensity of sensation already present, that the knock at the door must be the louder the more noise is going on within, is a defect in organic measurement, but it is not entirely absent in mechanical; scales which weigh by the ton do not respond easily or at all to minute weights. But, abstractly speaking, mechanic methods are in general far superior to organic; a fine balance weighs better than any arm, and a good camera pictures better than the best eye; that is, their ratio of discriminating sensibility is far greater than natural organs, and it may be as geometric series to arithmetic series. Practically, however, organic weighing and seeing are well adjusted to the demands of life. An appreciation of gravity, so far as it is of use to the organism, is secured, and if a finer sensibility were demanded it would be attained. That is, I am inclined to believe that the Weber-Fechner law of definite mathematical proportions is purely empirical, and does not mark a real limit or a fundamental psycho-physical law. If a man’s life and living depended on it, he could become a good weighing machine, and in time a race of organic weighers might be raised up which should vie in accuracy and range with the best scales now constructed. The quotient of sensitiveness is really indefinitely variable. It is probable, indeed, that deep sea organisms have a discriminative sensibility for both gravity and light far more delicate than the acutest human sense.
The whole subject of measurement of mental intensities must evidently be approached with the greatest care, and the diversities of researches in results and in their interpretation, is evidence that we have not completely isolated the facts we are in search of. Conscious experimentation must be allowed as tending to disturb sense. When attention is strained to marking sense increments it may very easily be deluded, and wrongly suppose as to feeling or not feeling. Consciousness is by no means infallible as to its own acts, and especially when artificial. Feelings may, and often do, originate subjectively by suggestion, and hence may have no direct reference to the external cause which is under experimental manipulation.
And not only have we thus to guard against a strong tendency to introspective and apperceptive error as to what we actually experience, or how we experience, but we have also to constantly bear in mind that every experience, every sensing, as of pressure, light, etc., is not an isolated phenomenon, but as resting upon and involving the past, it can never be a simple direct measure of the objective present, as a given weight or light. Every conscious experience, like all other vital organic phenomena, has thus an individuality and differs from every other as every leaf differs from every other, and so the laws of experience are capable only of general expression. Since all consciousness is self-integrating and brings up the past into itself, it is always more than any occasional reflection of a present phenomenon; in the finest analysis every consciousness must have an equation of its own.
However, there is a quotient of relation of physical stimulus, mechanically measured, with increase and decrease of both sense and of pleasure-pain. The pack-carrier feels in a certain proportion to his present load pressure of weight-increments, and pressure pains also augment, though probably not in strict corresponding ratio. It is a popular saying that the last straw breaks the camel’s back, and it is certain that pains rapidly culminate. It is probable that increments which may not be sensed may yet be felt as pain. In fact, it is but very gradually that sense of pressure is evolved as practically free of pain; as a mere cognitive process it is always secondary to pleasure-pain states which are felt directly from weights or but slightly objectified. Pleasure-pain which proceeds from weights gradually is driven to sensing them—the evolution of the pressure sense—and to noting variations, sense increments, and if, like marine organisms, we ranged through pressure zones, the significance of discriminative sensibility might be very great.
However, it is obvious that in its rise and in its whole evolution, pleasure-pain is bound up with the pressure sense, but not with the arm of the balance as a record. Hence it is possible that Weber’s law, so far as applicable, is in some measure a result of feeling interference. The simplicity of direct reaction is being destroyed by the hedonalgic law disturbing the direct ratio; we may thus feel an increasing pain from increasing weights, and have decreasing pressure sense. Beyond a certain point the law of increments, with reference to external standard for sensing and for pleasure and pain are in inverse ratio. On a very hot day we notice more and more strongly each additional degree of heat by the temperature sense, but beyond a certain degree, peculiar to the individual at the time, sense of heat will rapidly diminish as heat increases, and with increase of pain.
As to the number of feelings, of qualitatively distinct states, we must on a general doctrine of evolution pronounce this to be innumerable and indefinite. The present forms of feeling in human consciousness of course represent but a small fraction of the total number which have arisen in the course of psychic evolution. Every distinct form implies a long evolution of intermediate types which are now for the most part beyond our realization and so beyond cognition. The process of naming affords some slight clue to the importance and multiformity of feeling, though this denotes only a few of the most obvious points which have impressed themselves on the popular mind. Certainly the most striking fact to ordinary introspection, human and sub-human, is feeling, and the manifold variety of simple pleasure-pains and of emotions has always, and will always, attract most strongly the general attention. It would be a most interesting and profitable study to follow the course of language in its denotation of feeling. Varied expression for varied feelings is gradually achieved in vocal forms, which expressions become a language sense to denote the feeling expressed. Thus the hoarse bellow of rage will both express and denote rage. The vocal expression form as imitated is the earliest language form, and only very gradually does language assume the mechanical and arbitrary forms of its highest development. It is by imitating being mad vocally and otherwise, and pointing to the angered one, that the savage conveys the idea of anger. Gradually all but the vocal expression is dropped, and this conventionalized, becomes the origin of the word to denote the emotion in question. Feeling and emotion names are doubtless in their origin debased vocal expression forms, though in the later evolution of language this is generally not detectable, and various other more indirect associations control language. Only states of consciousness which have attained a considerable force and prominence receive notice in the vocabulary of common speech. For many variances of feeling there is no word denotation, but it may be given by intonation. The number of names of feeling is thus in any language, or in all languages, but a very rough index to the actual number of kinds of feeling, and we may expect that a thorough scientific analysis will develop as extended scientific nomenclature of feeling, as chemistry has of kinds of matter. At the present crude stage of psychology we must affirm that the number of cognizable, but unnamed feelings, far exceeds the number of the named, and that the number of the undiscriminated or the undiscovered feelings far exceeds the number of both forms.
On the whole, it has been the object of our present studies to point out with some definiteness the extent and mode of the early differentiation of feeling. Owing to the peculiar difficulties which beset this form of study and to which we have often adverted, our conclusions may seem rather meagre and uncertain, but it is sufficient if they emphasize a region of introspective study, which, though of the utmost practical importance, is yet the most neglected of all in psychic science; and we hope to have set forth the most probable general order of mental evolution with some distinctness as based on the struggle of existence. Mind, beginning in pure pain, and culminating on the feeling side in the higher emotions, contains an intermediate, continuous, indefinite number of forms, determined by the demands of life and preserved by natural selection, many of which are so entirely outgrown that they may be for ever beyond human conception, and many occurring only occasionally in human consciousness as survivals, and a large, yet comparatively small number constituting the present evolution phase of feeling in human consciousness. We have dwelt specially on the lower developments, the rise of objectification and its nature, the rise and value of emotion, with some characterization of the simpler and earlier emotions. Emotion is superior to and supplants sensation, though based thereon. The poison I fear, I abstain from without tasting; but with lower psychisms there must be a direct sensing of the thing before its experience quality is apprehended.