Now, the consonance of end has long been regarded as an inevitable deduction from the hypothesis of evolution. “That pains are correlatives of actions injurious to the organism,” wrote Mr. Herbert Spencer in his “Principles of Psychology,”[182] “while pleasures are the correlatives of actions conducive to its welfare, is an induction not based on the vital functions only. It is an inevitable deduction from the hypothesis of evolution, that races of sentient creatures could have come into existence under no other conditions. Those races of beings only can have survived in which, on the average, agreeable or desired feelings went along with activities conducive to the maintenance of life, while disagreeable and habitually avoided feelings went along with activities directly or indirectly destructive of life, and there must ever have been, other things being equal, the most numerous and long-continued survivals among races in which these adjustments of feelings to actions were the best, tending ever to perfect adjustment.” And he safeguards the position by adding: “It is frequently taken for granted that the beneficial actions secured must be actions beneficial to the individual; whereas the only necessity is that they shall be beneficial to the race.”
This aspect of the consonance is now quite familiar; but let us carefully note how completely dependent it is on natural selection. Mr. Herbert Spencer’s testimony is especially valuable, since he has always laid much stress on the hereditary transmission of acquired characters and still holds[183] “that the inheritance of functionally-caused alterations has played a larger part than Darwin admitted even at the close of his life; and that, coming more to the front as evolution has advanced, it has played the chief part in producing the highest types.” Now, in these types we certainly find a wide range of consonance between the psychological and the biological ends of behaviour; of which the phenomena of play may again be adduced as an example. Hence the special value of Mr. Herbert Spencer’s testimony to the part played by natural selection in establishing the consonance. “Only those races of beings,” he says, “can have survived in which, on the average, agreeable feelings went along with activities conducive to life;” and again, “The most numerous survivals must ever have been among races in which these adjustments of feelings to actions were the best.” The stress is here laid on the survival of those in which the consonance has obtained; the elimination of those in which it was absent: that is to say, on natural selection. And where else can it be laid? It is not the sort of thing which could be acquired. Suppose that, as we suggested above, an animal were born with a rooted hereditary aversion to everything nutritious and an inherited hunger for anything harmful and unfit for food. Under what conceivable conditions could such an animal acquire a complete change of its affective nature? Animals like things or they do not like them; only to a very limited extent, if at all, under natural conditions, can they learn to like them. We, indeed, can in some degree learn to take pleasure in that which at first, and by nature, is distasteful; but we do so by some external constraint, or from some motive of ideational origin. We put pressure upon ourselves, or have pressure put upon us, repeatedly to perform some irksome task; we fall into routine and custom; and the performance becomes so far second nature that its discontinuance produces an uncomfortable sense of something lacking in the daily round. Perhaps domestic animals learn to like the good offices we force them to perform for us. But here we have the element of external constraint, which is wholly, or almost wholly, absent under natural conditions. And there is no evidence that such acquired likings are inherited. That, however, is another question. Our present point is that, under nature, the conditions of such acquisition are lacking; so that, there being no acquisition, there is, in this case, nothing acquired to be transmitted.
But, so far as behaviour is concerned, “functionally caused alterations” are those due to the exercise of intelligence, by which the behaviour acquires direction and character in reference to the meaning introduced into the situations. See, then, the position to which we are logically driven. The acquisition of that which has beneficial value in behaviour depends on a consonance between psychological and biological end. But this consonance is dependent on survival, and, apart from special creation, or some kindred hypothesis such as Leibnitzian harmony, can be due to nothing else. Even if we grant, therefore, that the effects of acquisition are inherited, the conditions of beneficial acquisition are dependent on natural selection. And thus the inheritance of acquired characters, which is so often urged as a principle of evolution independent of natural selection, is, so far as intelligent behaviour is concerned, indirectly, if not directly, due to this very natural selection of which it is said to be independent. Surely, under these circumstances, the hypothesis in question may be said to be not only unproven, but altogether unnecessary.
And what is true of those diverse feelings which we group under the concepts pleasure and pain respectively, is true also of those more complex dispositions which we call emotional—using this term in a broad and comprehensive sense. We say that in their primary manifestations they are instinctive; and they certainly seem to accompany organic behaviour due to co-ordinated reflex actions. But the emotion, as instinctive, is a matter only of its first occurrence. In the course of experience it enters into conscious situations, the centres of interest in which have acquired meaning.
Take a particular case.[184] Your dog is dozing on the lawn in the sunshine. Suddenly he raises his head, pricks his ears, scents the air, looks fixedly at a gap in the hedge, and utters a low growl. Place your hand on his shoulder, and you will find that his muscles are all a-tremble; on his ribs, and you will feel how strongly his heart is beating. Soon the growing excitement leads to vigorous action, and he darts through the gap. You follow him across the lawn, look over the hedge, and see him facing his old enemy, the butcher’s cur. They are moving slowly past each other, head down, teeth bared, back roughened. You whistle softly. Such a call would generally bring him bounding to your feet; but now it is apparently unheard, at any rate unheeded. The two dogs have a short scuffle, and the cur slinks off. Your dog races after him; and he flees, yelping. The situation is over. Spot returns, wagging his short tail, jumps up at you playfully, and then lies down again on the grass. But now and then, for ten minutes or so, he raises his head and growls softly.
Let us briefly analyze the dog’s condition and actions, reading into them, conjecturally, the accompaniments in consciousness. As he lies on the lawn, he receives a sense-stimulus, auditory or olfactory. It has already acquired meaning, from many a tussle with the butcher’s cur. It has organic effects, and it generates a conscious situation which has acquired complexity through coalescence. As the result of this situation the head is raised, the ears pricked, and so on. The dog is on the alert. His attention is aroused. The muscles of neck, eyes, ears, are brought into play in such a way as to bring the senses to bear on the exciting object. He probably sees the cur through the gap in the hedge. The muscles of the frame are innervated so as to be in a state of preparation to act rapidly and forcibly. At the same time the vaso-motor system is disturbed, the heart-beat is quickened, respiration is altered; there is probably hardly an organ in the body which remains unaffected. Then the dog rushes through the hedge, and stands with bared teeth before his antagonist. A whole set of appropriate muscles are now strongly innervated. There is, perhaps, a double innervation, stimulating to activity and yet restraining from action. He bares his teeth and growls deeply. Attention is so concentrated that he heeds not, perhaps does not hear, his master’s whistle. He is keenly on the alert. The blood-system, respiratory organs, and all his inner machinery are still pulsating with nervous thrills; his back is up. Then he sees his chance, and flies at his opponent. Much that he has learnt in play, and all that he has learnt in earnest, comes to his aid in the short angry scuffle. And what we call his emotion of anger spurs him on to the fight; the cowardly dog in which this is lacking or is replaced by fear is spurred to flight. Each may contribute to self-preservation, but in different ways.
Now, we shall not attempt to determine how the distinctively emotional elements arise. Some think they arise by a sort of irradiating nervous diffusion in the nerve-centres as a direct result of the originating stimulus. Mr. Rutgers Marshall regards them as due to the motor activities in fight or flight; Professor William James contends that they have their source in the visceral affections of heart, lungs, glands, and so forth; Professor Lange attributes them to vaso-motor effects. The problem is a difficult one, and hard to determine by experiment; for we have to deal with a matter of primary genesis, of how they are at the outset introduced into the conscious situation. Experiments on animals which have already gained emotional experience cannot decide the question of genesis. Professor Sherrington, for example, has shown[185] that, after severance of the spinal cord in the lower region of the neck, and of the vagus nerves, by which “a huge field of vascular, visceral, cutaneous, and motor reaction” were “deprived of all connection with the nervous centre necessary to conscious response,” “the emotional states of anger, delight at being caressed, fear and disgust were developed with, as far as could be seen, unlessened strength.” But the avenues of connection were closed after the motor and visceral effects had played their parts in the genesis of the emotion on the hypothesis that the emotion is thus generated. Although new presentative data of this type were thus excluded, their re-presentative after-effects in the situation were not excluded. It is, moreover, an essential part of Professor James’s doctrine, as I provisionally accept it, that the “expression” and the visceral and vascular efforts are independent results of stimulation in certain ways, and that these independent results are conjoined through natural selection. Suppose we sever the connection through which the one takes effect, there is no reason to expect that the manifestation of the other would cease. Professor Sherrington cut off the channels of communication with the visceral and vascular apparatus: if the channels of expression remained open there is no reason why such expression should cease.
We need not, however, for our present purpose, attempt to ascertain how the distinctively emotional characteristics arise. It is sufficient that they are presumably present in the situation. Now, as Dr. Stout well points out,[186] the emotions generally presuppose the existence of certain specific tendencies. “The anger produced in a dog by taking away its bone presupposes the specific appetite for food. The anger produced in it by interfering with its young presupposes the specific tendency to guard and tend its offspring. So the presence of a rival who interferes with its wooing causes anger because of the pre-existence of the sexual impulse.” In general, we may say that emotional states are, under natural conditions, closely associated with behaviour of biological value—with tendencies which are beneficial in self-preservation or race-preservation—with actions that promote survival, and especially with the behaviour which clusters round the pairing and parental instincts. The value of the emotions in animals is that they are an indirect means of furthering survival. But how has the close association between emotional condition and the biological end it furthers been established? Again, we must say that under natural conditions it is not the sort of thing which could be acquired. And again we must urge that natural selection through survival is, apart from some theory of pre-established harmony, the only hypothesis in the field on which the close association can be explained.
There is one more point to which attention may be drawn. If there be one thing, and there certainly are not many, on which all writers on the emotions are agreed, it is as to their vagueness. They do not readily submit to definition, and cannot be described in a sentence. This is not due to any indefiniteness of biological end, nor to much indefiniteness in the mode of “expression;” it is due, rather, to an inherent dimness and haziness of psychological outline. We seem unable to focus them and get a clear-cut result. This is, no doubt, in part due to the complexity of emotional states. But, may it not be largely due to the fact that there is no necessity for definiteness? They fulfil their purpose just as well if they are vague. It is quite necessary for the dog to have a clear-cut impression of his antagonist; and, on the cognitive side of consciousness, meaning must be in some degree definite to be of real value. But, so long as the emotion raises the temperature, so to speak, to the boiling-point of vigorous action, it matters little what the psychological source of heat may be. If this be so, we should expect an emotional vagueness, since natural selection puts no premium upon emotional definiteness. And from this it follows, as a corollary, that, whereas we may infer that an animal’s perceptual products are probably closely similar to our own, since sight, touch, hearing, smell, and taste are of value in so far as they convey definite meaning, in interpreting their feelings and emotions we have less secure grounds of inference, since all that is requisite is that there should be a sufficiently high emotional temperature to afford the conditions for definite and vigorous action.
In conclusion, then, we may say that the primary purpose of the evolution of feeling and emotion is to promote beneficial behaviour, and that the observed consonance of the psychological end of attaining satisfaction, and the biological end of securing survival, seems to be due to natural selection—is, indeed, scarcely explicable on any other naturalistic hypothesis.