Recapitulating, then, we may define instinct as a psycho-organic propensity, not acquired by education or experience, but congenital by inheritance and identical in all members of the same zoölogical species, having as its physical basis the specific nervous organization of the animal and as its psychic basis a teleological coördination of the cognitive, emotional, and motor functions, in virtue of which, given the proper physiological state of the organism and the presence of an appropriate environmental stimulus, an animal, without consciousness of purpose, is impelled to the inception, and regulated in the performance, of complicated behavior which is sensually gratifying and, under normal circumstances, simultaneously beneficial to the individual, or the race.
Instinctive acts are performed without previous experience or training on the part of the animal, and are, nevertheless, at least in the majority of cases, perfect in their first performance. A few, like the pecking-instinct of young chickens, are slightly improvable through sentient experience, e.g. the young chick, at first undiscriminating in the choice of the particles which it picks up, learns later by associative memory to distinguish what is tasty and edible from what is disagreeable and inedible, but, for the most part, the perfection of instinctive acts is independent of prior experience. Hence instinct is entirely different from human reason, which, in the solution of problems, is compelled to begin with reflection upon the data furnished by previous experience, or education. The animal, however, in its instinctive operations, without pausing to investigate, deliberate, or calculate, proceeds unhesitatingly on the very first occasion to a prompt and perfect solution of its problems. Hence, without study, consultation, planning, or previous apprenticeship of any sort, and in the complete absence of experimental knowledge, that might serve as matter for reflection or as a basis for inference, the animal is able to solve intricate problems in engineering, geometry, anatomy, pharmaceutics, etc., which the combined intelligence of mankind required centuries upon centuries of schooling, research, and reflection in order to solve. Of two things, therefore, one: either these actions do not proceed from an intelligent principle inherent in the animal; or they do, and in that case we are compelled to recognize in brute animals an intelligence superior to our own, because they accomplish deftly and without effort ingenious feats that human reason cannot duplicate, save clumsily and at the price of prolonged discipline and incessant drudgery. “Perhaps the strongest reason,” says an anonymous writer, “for not regarding the activities of instinct as intelligent is that in such enormously complex sequences of action as, for instance, the emperor moth carries out in the preparing of an escape-opening for itself on its completing the larval and passing into the imago state, the intelligence needed would be so great that it could not be limited to this single activity, and yet it is so limited.”[15]
Intelligence is essentially a generalizing and abstracting power; hence, from its very nature, it could not be limited to a single activity. Bestial instincts, however, though frequently so amazingly complex and ingeniously purposive as to seem the fruit of profound meditation, are, nevertheless, confined exclusively to this or that determinate ability. They operate within narrow and preëstablished grooves, from which they never swerve to any appreciable degree, being but little modifiable or perfectible by experience. Bees always construct hexagonal cells, spiders stick to the logarithmic spiral, and beavers never attempt to put their engineering skill to new uses. Instincts have but little pliancy, their regularity and uniformity being such as to make the instinctive abilities definitely predictable in the case of any given species of animal. Now, the distinctive mark of intelligence is versatility, that is, aptitude for many things without determinate restriction to this or that. A man who is expert in one art may, by reason of his intelligence, be equally proficient in a dozen others. The biologist may be a competent chemist, and the astronomer an excellent physicist. Michel Angelo was a sculptor, a frescoer, a painter, an anatomist, an engineer, and an architect, while Leonardo da Vinci had even more arts to his credit. To predict before birth the precise form that a man’s ability will take is an impossibility. Certain aptitudes, such as a musical gift, are no doubt inherited, but it is an inheritance which imposes no rigid necessity upon inheriter; since he is free to neglect this native talent, and to develop others for which he has no special innate aptitude. With man, the fashion in clothing and the styles of architecture vary from day to day. The brute, however, never emerges from the rut of instinct, and each generation of a given animal species monotonously reproduces the history of the previous generation. Man, on the contrary, is capable of indefinite progress, as the march of human cultures and civilizations shows. Gregarious animals are restricted by their instincts to determinate types of aggregation, as we see in the case of ants and bees. Hence these insect communities are unacquainted with our sanguinary revolutions which overturn monarchies in favor of republics, or set up dictatorships in place of democracies; for, fortunately or unfortunately, as one may choose to regard it, man is not limited to one form of government rather than another.
Animals, then, notwithstanding their wonderful instincts, are deficient in precisely that quality which is the unique criterion of intelligence, namely, versatility. Each species has but one stereotyped ability, outside of which it is woefully stupid and inefficient. “So long,” says Fabre, “as its circumstances are normal the insect’s actions are calculated most rationally in view of the object to be attained” (“The Mason-Bees,” p. 167), but let the circumstances cease to be normal, let them vary never so little from those which ordinarily obtain, and the animal is helpless, while its instinctive predisposition becomes, not merely futile, but often positively detrimental. Thus the instinct, which should, in the normal course of events, guide night-flying moths to the white flowers that contain the life-sustaining nectar of their nocturnal banquets, proves their undoing, when they come into contact with the white lights of artificial illumination. In fact, the fatal fondness of the moth for the candle flame has become in all languages a proverb for the folly of courting one’s own destruction.
The animal may employ an exquisitely efficient method in accomplishing its instinctive work, but is absolutely impotent to apply this ingenious method to more than one determinate purpose. Man, however, is not so restricted. He varies at will both his aims and his methods. He can adapt the same means (a pocketknife, for instance) to different ends, and, conversely, he can obtain the same end by the use of different means (e.g. communicate by mail, or telegraph, or radio). Man, in a word, is emancipated from limitation to the singular and the concrete by virtue of his unique prerogative, reason, or intelligence, the power that enables him to generalize from the particular and to abstract from the concrete. This is the secret of his unlimited versatility. This is the basis of his capacity for progress. This is the root of his freedom; for his will seeks happiness in general, happiness in the abstract, and is not, therefore, compelled to choose any particular form or concrete embodiment of happiness, such as this or that style of architecture, this or that form of government, this or that kind of clothing, etc., etc. Teleology is but a material expression of intelligence, and may, therefore, occur in things destitute of intelligence, but versatility is the inseparable concomitant and infallible sign of an inherent and autonomous intelligence. Lacking this quality, instinct, however telic, is obviously not intelligence.
Another indication of the fact that no intelligence lies behind the instinctive behavior of brutes is manifest from their evident unconsciousness of purpose. That the animal is ignorant of the purpose implied in its own instinctive actions appears from the fact that it will carry out these operations with futile diligence and exactitude, even when, through accident, the purpose is conspicuously absent. Thus the hen deprived of her eggs will, nevertheless, continue the now futile process of incubation for twenty-one days, or longer, despite the fact that her obstinacy in maintaining the straw of the empty nest at a temperature of 104° F. serves no useful purpose whatever. She cannot but sense the absence of the eggs; she has not, however, the intelligence to realize that incubation without eggs is vain. The connection between the latter and the former is something that mere sense cannot apprehend. Hence the hen is not troubled by the purposelessness of her performance. Fabre gives many examples of this futile persistence in instinctive operations, despite their complete frustration. Alluding to the outcome of his experiments on the Mason-wasp Pelapaeus, he says: “The Mason bees, the Caterpillar of the Great Peacock Moth, and many others, when subjected to similar tests, are guilty of the same illogical behaviour: they continue, in the normal order, their series of industrious actions, though accident has now rendered them all useless. Just like millstones unable to cease revolving though there be no corn left to grind, let them once be given the compelling power and they will continue to perform their task despite its futility.” (“Bramble Bees,” pp. 192, 193.)
The instance cited by Dr. H. D. Schmidt is an excellent illustration of this inability of an animal to appreciate either the utility or futility of its instinctive behavior. Having described the instinct of squirrels to bury nuts by ramming them into the ground with their teeth, and then using their paws to cover them with earth, he continues as follows: “Now, as regards the young squirrel, which, of course, never had been present at the burial of a nut, I observed that, after having eaten a number of hickory nuts to appease its appetite, it would take one between its teeth, then sit upright and listen in all directions. Finding all right, it would scratch upon the smooth blanket on which I was playing with it as if to make a hole, then hammer with the nut between its teeth upon the blanket, and finally perform all the motions required to fill up a hole—in the air; after which it would jump away, leaving the nut, of course, uncovered.” (Transactions of the Am. Neurological Ass’n, 1875, vol. I, p. 129—italics his.) This whole pantomime of purposeless gesticulations, from the useless “Stop, look and listen!” down to the final desertion of the uncovered nut, is overwhelming evidence of the fact that the brute is destitute of any rational faculty capable of recognizing the telic aspect of its own instinctive conduct.
The claim is sometimes made that certain forms of animal behavior are not unconsciously, but consciously, telic. Bouvier, for example, claims that in the rare cases of the use of tools among the Arthropoda, we have evidence of the existence of intelligent inventiveness of a rudimentary kind. Thus the crab Melia carries a sea-anemone in its chela as a weapon wherewith to sting its prey into a condition of paralysis. The leaf-cutting ants of India and Brazil use their own thread-spinning larvæ as tools for cementing together the materials out of which their nests are constructed. The predatory wasp Ammophila urnaria uses a pebble to tamp the filling of its burrow. According to the Wheelers (cf. Science, May 30, 1924, p. 486), the hunting wasp Sphex (Ammophila) gryphus (Sm.) makes similar use of a pebble. As Bouvier notes, however, this use of tools appears “to be rather exceptional ..., showing itself only in the primitive state consisting of the use of foreign bodies as implements.” (Smithson. Inst. Rpt. for 1918, p. 456.) Moreover, the animals in question are limited to a concretely determinate kind of tool, which their environment supplies ready-made. Such a use of implements does not presuppose any power of abstraction and generalization. In fact, the presence of such a power is expressly excluded by the consideration that the animal’s so-called “inventiveness” is confined exclusively to one particularized manifestation.
At times the behavior of animals so closely simulates the consciously telic or intelligent conduct of men, that only severely critical methods enable us to discriminate between them. An experiment, which Erich Wasmann, S.J., performed upon ants will serve to illustrate this point. In one of his glass nests, Father Wasmann constructed an island of sand surrounded by a moat filled with water. He then removed from their “nursery” a certain number of the ant larvæ and placed them on the island. Thereupon the ants were observed to build a bridge of sand across the moat “for the purpose,” apparently, of rescuing the marooned larvæ. Such behavior seemed to imply an intelligent ordination of a means to an end. Wasmann’s second experiment, however, proved this inference to be wholly unwarranted; for, when he excavated a hole in the sand of the nest and filled it with water, the ants, stimulated by what to them was the disagreeable dampness of the marginal sand, were impelled to perform the reflex act of kicking about in the sand. This impulse persisted until all traces of the hole, the dampness and the water had been buried under a carpet of drier sand. Then, and then only, was the aforesaid impulse inhibited. Applying these results to the interpretation of the first experiment, we see that the “building of a bridge” in the first experiment was not intentional, but merely an accidental result of a kicking-reflex, with damp sand acting as a stimulator. Once the moat was bridged, however, the ants happened to find the larvæ, and were then impelled by instinct to carry the larvæ to their proper place in the nest. To see in such an incident a planned and premeditated rescue of the marooned larvæ would be grossly anthropomorphic. Nevertheless, had only the first experiment been performed, such an anthropomorphic interpretation would have seemed fully justified, and it was only by an appropriate variation of the conditions of the original experiment that this false interpretation could be definitively excluded.
Consciously telic behavior is distinguishable from unconsciously telic conduct only to the extent that it implies an agent endowed with the power of abstraction. Unless an agent can vary radically the specificity of the procedure, whereby it attains a given end, the purposiveness of its behavior is no evidence of its intelligence. “Among animals,” says Bergson, “invention is never more than a variation on the theme of routine. Locked up as it is within the habits of its species, the animal succeeds no doubt in broadening these by individual initiative; but its escape from automatism is momentary only, just long enough to create a new automatism; the gates of its prison close as soon as they are opened; dragging the chain merely lengthens it. Only with man does consciousness break the chain.” (Cf. Smithson. Inst. Rpt. for 1918, p. 457.)