Читать книгу The Story of the Mind - James Mark Baldwin - Страница 11

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It has already been pointed out that the animal has a very important share of the endowment which we call mind. Only recently has he been getting his due. He was formerly looked upon, under the teachings of a dualistic philosophy and of a jealous humanity, as a soulless machine, a mere automaton which was moved by the starting of certain springs to run on until the machine ran down. There are two reasons that this view has been given up, each possibly important enough to have accomplished the revolution and to have given rise to Animal Psychology.

First, there is the rise of the evolution theory, which teaches that there is no absolute break between man and the higher animals in the matter of mental endowment, and that what difference there is must itself be the result of the laws of mental growth; and the second reason is that the more adequate the science of the human mind has become the more evident has it also become that man himself is more of a machine than had been supposed. Man grows by certain laws; his progress is conditioned by the environment, both physical and social, in which he lives; his mind is a part of the natural system of things. So with the animal. The animal fulfils, as far as he can, the same sort of function; he has his environment, both physical and social; he works under the same laws of growth which man also obeys; his mind exhibits substantially the same phenomena which the human mind exhibits in its early stages in the child. All this means that the animal has as good right to recognition, as a mind-bearing creature, so to speak, as the child; and if we exclude him we should also exclude the child. Further, this also means—what is more important for the science of psychology—that the development of the mind in its early stages and in certain of its directions of progress is revealed most adequately in the animals.

Animal Instinct.—Turning to the animals, the first thing to strike us is the remarkable series of so-called animal Instincts. Everybody knows what animal instincts are like; it is only necessary to go to a zoölogical garden to see them in operation on a large scale. Take the house cat and follow her through the life of a single day, observing her actions. She washes her face and makes her toilet in the morning by instinct. She has her peculiar instinctive ways of catching the mouse for breakfast. She whets her appetite by holding back her meal possibly for an hour, in the meantime playing most cruelly with the pitiful mouse, letting it run and catching it again, and doing this over and over. If she has children she attends to their training in the details of cat etiquette and custom with the utmost care, all by instinct; and the kittens instinctively respond to her attentions. She conducts herself during the day with remarkable cleanliness of life, making arrangements which civilized man follows with admiration. She shows just the right abhorrence of water for a creature that is not able to swim. She knows just what enemies to fly from and when to turn and fight, using with inborn dexterity her formidable claws. She prefers nocturnal excursions and sociabilities, having eyes which make it safe to be venturesome in the dark. She has certain vocal expressions of her emotions, which man in vain attempts to eradicate with all the agencies of domestication. She has special arts to attract her mate, and he in turn is able to charm her with songs which charm nobody else. And so on, almost ad infinitum.

Observe the dog, the birds of different species, the monkeys, the hares, and you find wonderful differences of habit, each adapting the animal differently, but with equal effectiveness, to the life which he in particular is called upon to lead. The ants and bees are notoriously expert in the matter of instinct. They have colonies in which some of the latest principles of social organization seem to find analogues: slavery, sexual regulations, division of labour, centralization of resources, government distribution of food, capital punishment, etc.

All this—not to stop upon details which the books on animal life give in great abundance—has furnished grounds for speculation for centuries, and it is only in the last generation that the outlines of a theory of instinct have been filled in with substantial knowledge. A rapid sketch of this theory may be drawn in the following pages.

1. In instinct in general there is a basis of inherited nervous tendency toward the performance of just the sort of action which the instinct exhibits. This nervous tendency shows itself independently of learning by the individual in a great many cases, as in the instinct of sucking by young animals, pecking for food by young fowls, the migrating actions of adult mammals and birds, the courting movements of many varieties of animal species. In all this we have what is called the "perfect" instinct. To be perfect, an instinct must be carried out successfully by the animal when his organism is ready, without any instruction, any model to imitate, any experience to go upon. The "perfect" instincts are entirely congenital or inborn; the nervous apparatus only needs to reach the proper stage of maturity or growth, and forthwith the instinctive action is performed as soon as the external conditions of life are such as to make its performance appropriate and useful.

2. On the other hand, many instincts—indeed, probably the greater number—are not perfect, but "imperfect." Imperfect instincts are those which do not fully equip the animal with the function in question, but only take him part way to the goal. He has a spontaneous tendency to do certain things, such as building a nest, singing, etc.; but he is not able to do these things adequately or perfectly if left to himself from birth. This sort of endowment with imperfect instincts has been the field of some of the most interesting research in animal psychology, and has led to a new view of the relation of instinct to intelligence.

3. It has been found that young animals, birds, etc., depend upon the example and instruction of adults for the first performance of many actions that seem to be instinctive. This dependence may exist even in cases in which there is yet a congenital tendency to perform the action. Many birds, for example, have a general instinct to build a nest; but in many cases, if put in artificial circumstances, they build imperfect nests. Birds also have an instinct to make vocal calls; but if kept from birth out of hearing of the peculiar notes of their species, they come to make cries of a different sort, or learn to make the notes of some other species with which they are thrown.

4. The principal agency for the learning of the animals, and for the supplementing of their instincts, is Imitation. The sight of certain movements on the part of the adult animals, or the hearing of their cries, calls, notes, etc., leads the young to fall into an imitation of these movements or vocal performances. The endowment which such a young animal has in the direction of making movements and cries similar to those of his species aids him, of course, in imitating these in preference to others. So the endowment and the tendency to imitate directly aid each other in all such functions, and hurry the little creature on in his acquisition of the habits of his species. We find young animals clinging even in their imitations pretty closely to their own proper fathers and mothers, who are thus enabled to bring them up comme il faut.

5. There is every reason to think, moreover, that the tendency to imitate is itself instinctive. Young animals, notably the monkey and the child, fall spontaneously to imitating when they reach a certain age. Imitation shows itself to be instinctive in the case of the mocking bird, the parrot, etc. Furthermore, the mechanism of this function of imitation is now very well known. The principle of psychology recognised above under the phrase Kinæsthetic Equivalents, teaches us that the idea of a movement, coming into the mind through sight or some other sense, stirs up the proper apparatus to bring about the same movement in the observer. This we see in the common tendency of an audience to repeat the gestures of a speaker, and in many similar cases. When this principle is extended to include all sorts of experiences besides those of movement, we have what is generally called Imitation. Moreover, every time that by action the child imitates, he perceives his own imitation, and this again acts as a "copy" or model for another repetition of the act, and so on. This method of keeping himself going gives the young animal or child constant practice, and renders him more and more efficient in the acts necessary to his life.

6. It is evident what great profit accrues from this arrangement whereby a general instinct like imitation takes the place of a number of special instincts, or supplements them. It gives a measure of plasticity to the creature. He can now respond suitably to changes in the environment in which he lives. The special instincts, on the contrary, are for the most part so fixed that the animal must act just as they require him to in this or that circumstance; but as soon as his instinct takes on the form of imitation, the resulting action tends to conform itself to the model actions of the other creatures which set "copies" before him.

These more or less new results due to recent research in the province of Instinct have had direct bearing upon theories of the origin of instinct and of its place in animal life.

Theories of Instinct.—Apart from the older view which saw in animal instinct simply a matter of original created endowment, whereby each animal was made once for all "after his kind," and according to which there is no further reason that the instincts are what they are than that they were made so; apart from this "special creation" view, two different ideas have had currency, both based upon the theory of evolution. Each of these views assumes that the instincts have been developed from more simple animal actions by a gradual process; but they differ as to the elements originally entering into the actions which afterward became instinctive.

1. First, there is what is called the Reflex Theory. This holds that instincts are reflex actions, like the closing of the eye when an object threatens to enter it, only much more complex. They are due to the compounding and adding together of simple reflexes, in greater and greater number, and with increasing efficiency. This theory attempts to account for instinct entirely in terms of nervous action. It goes with that view of evolution which holds that the nervous system has had its growth from generation to generation by the continued reflex adjustments of the organism to its environment, whereby more and more delicate adaptations to the external world were secured. In this way, say the advocates of this theory, we may account for the fact that the animal has no adequate knowledge of what he is doing when he performs an act instinctively; he has no end or aim in his mind; he simply feels his nervous system doing what it is fitted to do by its organic adaptations to the stimulations of air, and earth, and sea, whatever these may be.

But it may be asked: Why do succeeding generations improve each on its parents, so that there is a gradual tendency to perfect the instinct?

The answer to this question brings up another great law of biology—the principle of Variations. This principle states the common fact that in every case of a family of offspring the individual young vary slightly in all directions from their parents. Admitting this, we will find in each group of families some young individuals which are better than their parents; these will have the advantage over others and will be the ones to grow up and have the children of the next generation again, and so on. So by constant Variation and Natural Selection—that is, the "Survival of the Fittest" in competition with the rest—there will be constant improvement in the Instinct.

2. The other theory, the rival one, holds that there are some instincts which show so plainly the marks of Reason that some degree of intelligent adjustment to the environment must be allowed to the animal in the acquiring of these functions. For example, we are told that some of the muscular movements involved in the instincts—such, for example, as the bird's nest-building—are so complex and so finely adjusted to an end, that it is straining belief to suppose that they could have arisen gradually by reflex adaptation alone. There is also a further difficulty with the reflex theory which has seemed insurmountable to many of the ablest psychologists of animal life; the difficulty, namely, that many of the instincts require the action of a great many muscles at the same time, so acting in "correlation" with or support of one another that it is impossible to suppose that the instinct has been acquired gradually. For in the very nature of these cases we can not suppose the instinct to have ever been imperfect, seeing that the partial instinct which would have preceded the perfect performance for some generations would have been not only of no use to the creature, but in many cases positively injurious. For instance, what use to an animal to be able partly to make the movements of swimming, or to the birds to build an inadequate nest? Such instincts would not be usable at all. So we are told by the second theory that the animals must have had intelligence to do these things when they first acquired them. Yet, as is everywhere admitted, after the instinct has been acquired by the species it is then carried out without knowledge and intelligent design, being handed down from generation to generation by heredity.

This seems reasonable, for we do find that actions which were at first intelligent may be performed so frequently that we come to do them without thinking of them; to do them from habit. So the animals, we are told, have come to do theirs reflexly, although at first they required intelligence. From this point of view—that although intelligence was at first required, yet the actions have become instinctive and lacking in intelligent direction in later generations—this is called the theory of Lapsed Intelligence.

This theory has much to commend it. It certainly meets the objection to the reflex theory which was stated just above—the objection that some of the instincts could not have arisen by gradual reflex adaptations. It also accounts for the extremely intelligent appearance which many instincts have.

But this view in turn is liable to a criticism which has grown in force with the progress of biological knowledge in recent years. This criticism is based on the fact that the theory of lapsed intelligence demands that the actions which the animals of one generation have acquired by their intelligence should be handed down through heredity to the next generation, and so on. It is evident that unless this be true it does no good to the species for one generation to do things intelligently, seeing that if the effects on the nervous system are not transmitted to their children, then the next and later generations will have to start exactly where their fathers did, and the actions in question will never become ingrained in the nervous system at all.

Now, the force of this criticism is overwhelming to those who believe—as the great majority of biologists now do[1]—that none of the modifications or so-called "characters" acquired by the parents, none of the effects of use or disuse of their limbs, none of the tendencies or habits of action, in short, none of the changes wrought in body or mind of the parents during their lifetime, are inherited by their children. The only sorts of modification which show themselves in subsequent generations are the deep-seated effects of disease, poison, starvation, and other causes which concern the system as a whole, but which show no tendency to reproduce by heredity any of the special actions or functions which the fathers and mothers may have learned and practised. If this difficulty could be met, the theory that intelligence has been at work in the origination of the complex instincts would be altogether the preferable one of the two; but if not, then the "lapsed intelligence" view must be thrown overboard.