The conditions of pleasure and pain, physiological and psychological, are matter of dispute; and the dispute is complicated by the confusion of the physiological with the psychological problem. It will be evident, however,—if only we keep different things clear of each other,—that both kinds of explanation are possible, and that they are distinct from one another. The question of the nervous antecedents and concomitants of feeling is one thing, and quite distinct from the question which now arises of the mental antecedents or concomitants of feeling. And here the theories which have attempted a generalisation of the phenomena are, in the light of recent inquiry, mainly two: the theory that pleasure follows, or is the sense of, increase of life, and that which holds it to be the concomitant of unimpeded conscious functioning or of medium activities.
(α) Pleasure not definable as the sense of increased vitality;
The former theory[179] might be put forward as indicating how it is possible to institute a connection between pleasure and evolution. But it has been already shown that neither the actual facts of life, nor the tendencies to action, can be so interpreted as to make their nature and development correspond, with any degree of exactness, with pleasure and its increase.[180] Nor is it possible to make out that every pain corresponds to a loss of vitality, every pleasure heightens it. On the contrary, the assertion that pleasure-giving actions and life-preserving actions coincide, is due to a hasty generalisation which cannot include all the facts. That it holds throughout a considerable extent is true. Pleasure is, at any rate, a usual accompaniment of the normal processes of the development of life; and pain reaches its climax in death. But yet there is a broad margin of experience for which the generalisation is incorrect. There are numerous cases of painful and pleasurable sensations which cannot be shown to be, respectively, destructive of, and beneficial to, vitality. As Mr Bain, who always keeps the facts in view, admits, with regard to the feelings connected with the five senses, "we cannot contend that the degree of augmented vital energy corresponds always with the degree of the pleasure."[181] The same discrepancy may be observed in more complex experiences. The effort after a fuller life, whether physical or mental, even when its ultimate success is not doubtful, may bring more pain than pleasure; while the life which never strains its powers towards the limits of endurance, may experience almost uninterrupted pleasure: but such pleasure is the sure herald of the process of degeneration.
(β) may be held to depend on medium or normal functioning.
The theory that pleasure follows increased vitality, and pain decreased vitality, is supplemented or opposed in modern psychology by the theory that feeling depends on function: that pleasure is the concomitant of medium activities,[182] or of conscious functioning, which is unimpeded and not overstrained[183]—pain accompanying the opposite condition. The objection urged against this view, that it leaves the so-called "passive pleasures" out of account, seems to be made without sufficient consideration of what is meant by attributing passivity to pleasure. All that such an expression can denote, would appear to be that, in the pleasurable experience referred to, no exercise of the muscles is implied, not that such an experience can take place without any conscious activity on the part of the subject. At the same time, the theory that pleasure in all cases depends upon function, must be admitted to be obliged to call in the aid of hypothesis in order to explain all the facts. If the generalisation required by the theory can be made out, it must be by emphasising the fact that feeling is never properly regarded as purely passive, but implies subjective reaction; and by supposing that the variation of feeling between pleasure and pain depends on a difference in the character of this subjective reaction. At the same time, the complete accuracy of this generalisation is not of vital importance here, as it is mainly with the feeling which manifestly results from activity or functioning that we are concerned.
Modification of pleasurable characteristics of objects
Whether pleasure depends upon increase of vital energy, or upon unimpeded or medium functioning, it must be subject to modification along with the conditions under which life may continue and increase, or the modes of activity which may be carried on without opposition and in moderation. This constant modification of the objects in which one takes pleasure, or which give one pain, is, indeed, a fact which must be admitted by any theory of feeling. A state of mind may be at first pleasurable; but, if it be long-continued, the pleasure will give way to the pain of monotony. The same is true of a painful state of mind: its continuance does not prolong the same intensity of painful consciousness, but the sensibility becomes dulled and the pain diminishes. The transition is still more striking in the case of motor activities. In learning to walk, or to ride, or to play any instrument, the first experiences are those of painful effort. Gradually, however, the co-ordinations of movement required entail less and less pain, till the feeling passes over into its opposite, and we have a pleasurable sense of successful effort and well-adapted functioning. But, just as pain gave way to pleasure, so pleasure itself subsides, the action becomes merely reflex and passes out of consciousness altogether, unless it be so long continued as to produce fatigue—that is, pain. Habit, as Dumont remarks,[184] intensifies perceptions, but weakens pleasure and pain.
suggests that feeling depends on objective intensity.
These are psychological facts—not mere theories—which hold true even of the individual experience. But they have led psychologists to the theory, supported by a vast amount of direct experiment, that there is no object or action which can be said to be absolutely and in itself either pleasant or painful.[185] The feeling of pleasure or pain accompanying the object is a function of its intensity in relation to the subject. This proposition cannot, indeed, be fully demonstrated regarding each simple sensation: to the emotions into which intricate relations of perceptions enter, it does not apply, till their complexity has been reduced. Some sensations and perceptions are certainly felt as painful in any intensity in which they are distinctly present to consciousness. But, although this is a real difficulty, it does not seem insuperable. The instances which Mill cites[186] to throw doubt on the generalisation that quality of feeling depends on intensity are unfortunately chosen for his purpose. For—to take his example—the taste of rhubarb is to many not painful but pleasant; and, indeed, every case of acquired taste shows that pleasure and pain can be modified through habit and custom, and suggests that, even in the case of those sensations which are painful in any form we have been able to experience them, there is a degree of intensity below which they would, if experienced, be pleasant. Experiment has proved of the majority even of sensible qualities, and analogy leads us to conclude of all, that there is a degree in which each may be pleasant, and a degree in which each may be painful, and, between them, a—real or imaginary—zero-point of feeling, where there is neither pleasure nor pain. This must, it is true, be received as a hypothesis only; but it is a hypothesis which is suggested by a wide range of facts, and which is able to include even those facts with which it is seemingly inconsistent, by supposing that could their intensity be indefinitely diminished without their passing out of consciousness, these sensations would reach a point after which they would be felt as pleasant and not as painful. Further, experiment shows that this dividing-point which separates the two poles of feeling is not always placed at the same degree of intensity, that it differs not only for every object, but for each individual subject as well, and that it undergoes modification in the course of the subject's development.[187]
What is true of sense-perception is still more evident regarding those experiences in which the activity of the subject is more obviously involved. As any function may, if carried beyond a certain degree of intensity, be painful, so any function consistent with life may be a source of pleasure.