INSTINCT. It is a tendency, an inner impulse, which determines and directs a complex of spontaneous and coordinated external acts by means of which the animal satisfies the needs of its relational life. Instincts are at least as numerous as the various needs of the animal and may concern either a specific object (the fox that goes in search of the hare) or a specific action (the bird that builds its nest). They aim at a twofold purpose: the preservation of the individual, so that it seeks food (the spider, the larva of the *formicaleone*) or stores it for the future (bees, ants) or defends itself from enemies (various forms of nests, color mimicry, feigning death, self-mutilation, migrations); and the preservation of the species (choice of safe places, provision of different food for the offspring, training).
**1. CHARACTERISTICS OF INSTINCT.** The empirical characteristics of instinct can be reduced to the following: 1) *Adaptability to particular ends to be achieved.* In this regard, the animal world, especially that of insects, displays wonders; nothing is more ingenious than the behavior of the beaver in building dams; of the bee in arranging and forming hexagonal cells, solving the geometric and economic problem of obtaining the maximum amount of honey with the minimum expenditure of wax; of the leaf-rolling weevil, which cuts the birch leaf according to a formula of differential calculus, discovered only recently; of the *ammophila*, a vegetarian, which provides its carnivorous larva with a live but immobilized butterfly caterpillar by first stinging its nerve centers. 2) *Blindness*, in the sense that the animal does not know, under the aspect of purpose, the end that it nevertheless achieves so admirably with its action, nor the proportion that the means it uses have to this end. It knows the movements it performs, which are in fact means ordered to its own good or that of the species, but it does not perceive the end as such, nor the means as such. This is so true that if circumstances change or it is disturbed in its work, it continues to perform acts without realizing that they have become useless (the spider, for example, which energetically carries and defends its cocoon, continues to drag and defend a cork ball substituted for the cocoon; birds feed their chicks for a certain time, then abandon them even if, due to lack of food, they see them die of hunger). 3) *Specificity.* Instincts are characteristic of the species. Each species of spider spins the same type of web; each species of bird builds the same type of nest, so much so that the species of the bird can easily be guessed from the characteristics of the nest. Sometimes there are characteristic acts within the same species; for example, the instinctive acts of the queen bee are different from those of the drones, which in turn do not have the instinct to make honey and produce wax. 4) *Preformation*, in the sense that instinct is innate, spontaneous, natural, not learned from experience; the larva of the *formicaleone* performs its work perfectly as soon as it hatches from the egg, without any prior training from its parents, who are no longer present; the gosling, hatched by a hen, immediately runs to the water and swims, despite the frightened hen’s cries; the squirrel makes a store of hazelnuts for its first winter, which it does not know, just as it will do for subsequent winters. Here, however, a distinction must be made between primary and secondary instincts. Primary instincts are those that are immediately perfect and not further perfectible (e.g., pecking for chicks, suckling for mammals); secondary instincts are those that are less indispensable and can be perfected through practice and experience (e.g., birds learn to sing, dogs learn to catch prey in one way or another; in migrations, the older ones lead the flight; all animals learn to fear hunting rifles; many species of fish no longer bite the hook after one of them has been caught). And in general, it is observed that the more developed the psychic life is—which happens as one ascends the scale of species—the more the automatic efficacy of instinct decreases. This fact also allows for the training and domestication of higher animals, which, through psycho-physiological habits, can develop new tendencies and abilities within themselves. 5) *Immutability*; instincts, that is, manifest themselves always with the same activities (bees today work exactly as they did in Virgil’s time, who sang of them in the *Georgics*; old individuals know no more than the young). However, a certain degree of plasticity, of flexibility in response to environmental circumstances, must also be admitted (e.g., the wren now uses threads woven by human hands to make its nest; and yet it is certain that the art of weaving is not as old as man; the spider adapts its web to the diversity of support points where the individual threads are woven). 6) *Coordination*, in the sense that instinctive acts, often very complex and ingenious and requiring time, are not performed haphazardly but appear to be governed and directed toward the purpose to be achieved, and do not cease until it is achieved. They thus have a finality toward which, even in their most complex diversity, they converge. 7) *Correlation with the development and determining situations of the organism.* Thus, the instinct of self-preservation in insects with metamorphosis produces different behaviors depending on whether the insect is in the state of caterpillar, chrysalis, or perfect form; the sexual instinct manifests itself after maturation and disappears after the involution of the reproductive organs; worker bees shift from the behavior of nurses of young larvae, which in the first days of life remain sedentary in their cells, to that of wax producers when the glands secreting the nutritive liquid undergo involution and those producing wax develop strongly, and finally to that of honey gatherers when the honeycombs are formed; similarly, a lack of necessary food substances or indigestion prompts the search for other specific foods that are not sought under other circumstances.
II. NATURE OF INSTINCT
From a consideration of the characteristics mentioned above, various conceptions have arisen regarding the nature of instinct:
1) **Mechanistic Theory.** Descartes, mechanistic philosophers, and defenders of the theory of "tropisms" (J. Loeb, M. Verworn, etc.), who, between matter and spirit, do not admit the third element that is life, reduce instinct to mere physiological reflexes it elicits and the animal to a mere automaton. This openly contradicts experience. The spider that repairs its web torn by a gust of wind, the insect that remedies an accident while building its honeycomb, demonstrate that circumstances can, to a certain extent, determine the insertion into the series of instinctive acts of a new act, which has become accidentally necessary in order to continue and complete the instinctive cycle. Moreover, the modifications that, according to circumstances, the beaver can make to its dam, the partridge to its shelter, demonstrate in instinct a certain plasticity. But if the sequence of acts is purely mechanical, it cannot be interrupted, completed, or modified. Instinct presupposes reflexes, whether simple or associated, but it is not to be confused with them; rather, it directs them toward their end.
2) **Anthropomorphic Theory.** Other philosophers, and many naturalists, struck by the marvels of instinctive activity, would attribute to animals an intelligence like that of humans, albeit of a lower or rudimentary degree. Experience, however, teaches that instinct does not require an intellectual cognition that would not explain the uniformity and constancy of instinctive actions (cf. below, V).
3) **Mystical Theory.** This sees in instinct a mysterious intelligence, having nothing in common with human intelligence, but rather a kind of intuition, by which, for example, animals are said to foresee the weather, catastrophes, and flee to take shelter; they eat because they intuit that otherwise they would die of starvation. Yet these facts admit of quite another interpretation: animals have no intuition of time; rather, they are so constituted that certain particular sensations produce reflexes that prepare them for changes in the weather; thus they eat because the sensation of hunger arouses those reflexes that drive them to seek food.
4) **Psychological Theory.** Instinctive behavior, as revealed by the typical forms indicated above, is an activity that bears the imprint not only of a causal connection between its various manifestations and between these and the structures of the organism, but also of a direction toward an end and of an objective experience. It presents itself clearly as a whole, as an organized unity directed toward an end that, while it unfolds, is not yet in act, and, once attained, will mark its conclusion. Even in the subject performing the action, one must suppose an inner activity, sure and unconscious, that organizes in a certain way the raw data, receptive and effective, of the organism, so as to link them into a whole that unfolds successively in time and space. It is therefore the direction, or rather the "sense," the fundamental and characteristic note of instinct; it must therefore be considered a psychological activity (A. Gemelli-G. Zunini [cf. bibl.], p. 340). This inner activity, which provokes external activity and the movements and actions necessary to the end, is, according to St. Thomas and Scholastic philosophy, proper to a particular faculty that the animal possesses, of discerning what is suitable or harmful to it, and is called the "estimative" power (St. Thomas, *De veritate*, q. 18, a. 7, ad 7; *De anima*, lib. III, lect. 5).
III. FUNCTIONING OF INSTINCT
Instinct is conditioned by a twofold factor:
a) the natural predisposition of the animal's organism (physiological aspect);
b) perception, which may be either an internal organic sensation or a perception, accompanied by the relative representation, of an external object, e.g., the sight of a puddle, a cry, a song, an odor, etc. (psychological aspect).
Therefore, by virtue of the animal's natural predisposition, certain objects provoke in it determinate representations and sensations, which set in motion the instinctive tendency, and then the animal acts under the impulse of these sensations and the representations that accompany them; these, of course, vary with the varying circumstances currently given and thus cause the instinctive act to vary by adapting it to them. For example, the cat does not always make the same leap to pounce on the mouse, but proportions it to the distance, the immobility or movement of the prey; the amophila, which fails to immobilize its victim with the first sting, repeats II. This explains the cleverness observed in the actions of animals, which is an appreciation of the forms of the object, spatial relationships, and the movements to be made or avoided or repeated.
IV. ORIGIN OF INSTINCT
According to the various ways of conceiving the nature of instinct, various theories have been devised regarding its origin, which may be grouped as follows:
1) **Theory of Adaptation:** instinct would derive from the necessity for the animal to adapt to external conditions; a kind of struggle for existence under the alternative of adapting or dying (J. B. Lamarck, C. Darwin, H. Spencer, etc.). This cannot be, because animals (the bee that makes honeycomb cells, the sheep that flees from the wolf) would perish before being able to adapt.
2) **Theory of Individual Habit:** instinct is caused by the habit contracted of always acting in a certain way either through one's own experience, imitation, or education (S. Condillac, R. Russell-Wallace, etc.). To this it may be objected that instinct already exists from the first instinctive act (the bird builds its first nest with the same ease and perfection as subsequent nests; the sheep flees from the wolf the first time it sees it). If instinct were the fruit of education, the first time it would not act as perfectly as the second, third, etc., unless one were to attribute to animals, which perform such complex and marvelous instinctive acts, a capacity for learning such that they succeed at once where man would require much more time; imitation, moreover, cannot take place at least in those cases in which, for example, insects have no opportunity even for a moment to see their parents, who die before the larva emerges from the egg. This does not preclude the insertion of acquired automatisms into an instinctive act, thus complicating their interpretation.
3) **Theory of Hereditary Habit:** instinct would be transmitted by parents to offspring (as generally held by evolutionists). But then it would not be explained by whom the progenitors of a given species could have acquired the instincts transmitted; moreover, while some instincts may perhaps be inherited, many are not explained by heredity, e.g., the queen and drones of bees do not work but reproduce; the worker bees, however, generated by them, work with marvelous skill and do not reproduce.
4) **Theory of Perception:** instinct would be produced by the perception of external objects. But it must be observed that perception is a necessary factor in setting instinct in motion and thus does not create it but presupposes it; moreover, external senses do not perceive the reason for utility, otherwise how is it that the bird gathers straws for its nest only at certain times of the year and not on other days, when it sees the same straws of the same color? Why does the sparrow choose straw for its nest and the swallow mud?
The origin of instinct, like that of intelligence and will, presupposes the solution of the problem of the nature of life and its finality; it cannot therefore be confined to experimental science alone, but must rise to metaphysics, which deals precisely with the origin of living beings and the faculties with which they were endowed by their supreme Author in view of the ends assigned to each species.
V.
II. NON È INTELLIGENCE
That animals possess intelligence is an ancient opinion, at least implicitly affirmed by the supporters of the transmigration of human souls into beasts; and it is upheld, even in later times, by H. Rorarius and M. Montaigne; in recent times by the advocates of the so-called “folk psychology” (A. Brehm, G. J. Romanes) following C. Darwin, and then by those evolutionist naturalists who classify animal actions into two orders: those performed in a manner conforming to an end, but antecedently to any experience, would belong to instinct, which acts mechanically; those instead performed by virtue of their own experience would belong to intelligence, which would differ from the human only in degree.Philosophy, however, and the more careful study of the phenomena offered by experience, conducted by eminent naturalists (e.g., J. H. Fabre, G. Surbled, L. T. Hohbause, J. B. Watson, J.-A. Plateau, W. Wagner, E. Claparède, J. Lubbock, W. Wundt, E. L. Thorndike, A. J. Kin-naman, etc.), assert with certainty that the operations of brute animals do not proceed from intelligence, because they give no sign of it that proves its presence or necessity; indeed, they give signs of possessing none at all. By intelligence is meant the faculty of forming and understanding abstract, universal concepts, of knowing the relations between cause and effect, between means and end, of formulating judgments and reasoning, and not merely of associating different representations; and finally, of reflecting upon one’s own actions with a view to continuous adaptation and improvement.
Now intelligence, precisely because its operations are directed by abstract and universal concepts, is not limited to a single kind of operation; for example, one who is guided by the abstract idea of “house” is not limited, in building it, to a single material (e.g., wood), nor to a single type; hence the possibility that the same architect may build structures in the most varied styles. In animals, however, individual species—and sometimes even individual subspecies—have only one kind of operation, and all individuals belonging to them perform it in the same way; instinctive acts are uniform and constant.
Moreover, among the attributes of intelligence are counted language, progress, the notion of God and of a moral law, the tendency toward supersensible goods—attributes that are not found in animals. These, in fact: 1) do not possess the true faculty of language, which presupposes knowledge of the external signs (words or gestures) used, nor of the relations between word and word, gesture and gesture, nor of the purpose for which one speaks and gestures and seeks to communicate one’s ideas and knowledge to others. They do, to be sure, have an appearance of language (cries, barks, hisses, whistles, etc.), but this is nothing more than an externalization of their internal appetites and affections, which in turn arouse in other animals similar appetites or affections, or tendencies to imitation or associations suited to make them act in this or that way, in this or that direction. The hen, for example, with certain cries warns of danger; at those cries the chicks run to take shelter under her wings; similarly, the cries of gulls, partridges, lapwings, and marmots signal the approach of danger. That cry manifests the passion, the affection aroused in the hen or the bird by the danger. It will also have the effect of putting the chicks or companions on guard; but in itself the cry is nothing more than a pure psychological phenomenon; the running away of the chicks is also a psychological phenomenon, a manifestation of the affection produced in them by that particular cry of the hen. In other words, it is one thing for nature to direct the hen’s cry toward the safety of the chicks, and quite another for the hen to intend with that cry to give a warning, to call the chicks, as a mother would call her children. *“Etsi brutta animalia aliquid manifestant, non tamen manifestationem intendunt; sed naturali instinctu aliquid agunt ad quod manifestatio sequitur”* (Summ. theol., 23-2°, q. 10, a. 1). Thus are explained all those expressions of brute animals that we perceive as directed toward others, as signals. In fact they serve as signals, but the brute does not perceive them as such, does not use them with the purpose of warning others; the direction is only affective and material, not intellectual and formal. The same must be said of the supposed language of bees and ants that attract their companions to where they have found an abundance of honey or sugar or grain. The fact can be explained by the gatherings, or contacts, or palpations provoked on the one hand by the satisfaction of having found something good and on the other by the perception that these gestures elicit the instinctive action of rushing to the fortunate spot. It cannot therefore be asserted that brute animals speak, nor, much less, that they understand one another. To understand one another, an agreement would be necessary about the meaning of that cry, of that particular movement. But such an agreement does not occur, for example, the first time the chick hears the hen’s alarm or the kitten sees the dog. 2) Brute animals, moreover, are capable only of those kinds of progress that derive from the association of images and from memory; they do not modify their way of acting except by virtue of these organic and sensory faculties. While man exhibits manifold variations and progress in the sciences and arts, in brute animals one can find only variations in practical procedures, accidental and within the range of variations of an organ fixed in its specific structure; it can never free itself in its actions from the style and measure imposed by nature on its appetite, its imagination, and even its inventiveness. 3) Brute animals, as daily experience attests, show no sign of a tendency toward supersensible things, nor any sign of religion or moral law. Otherwise, one would not see them continually indulging their appetites, abandoning or killing sick individuals, as is regularly observed in many species, nor, as in others, the female devouring the male after the act of reproduction.
It is true that at times one observes in brute animals actions that might seem to display a kind of morality, such as obedience, gratitude, repentance, love toward a master, even to the point of exposing themselves to danger of life for him or dying on his tomb; but these actions have only an apparent resemblance to acts of true virtue; in reality they proceed solely from sensitive affection, from the memory of past facts and circumstances, e.g., from love, from the memory of past pleasures, from fear, etc.
To consider many animal behaviors as forms, albeit primitive, of intelligence, also clashes with what morphology and the physiology of the brain tell us. It is now clearly demonstrated that higher psychic functions, and among these the foreknowledge of the future and foresight in that regard, and acts of will, etc., are linked in man to the presence of definite cortical parts of the cerebral hemispheres, localized especially in the frontal lobes and prefrontal cortex. These cortical parts are absent in all animals, even in those, such as anthropoid apes, that are morphologically most similar to man. It is well known how the destruction of these centers in man leads to the loss of all intellectual acts, and therefore intelligence cannot be attributed to beasts, which normally lack these centers.
To complete the discussion, one may mention several famous animals that were cited as examples of "clever brutes": the Berlin horse Clever Hans, the Elberfeld horses, the Mannheim dog, the Vienna chimpanzees Maia and Basso of Frankfurt, etc. These animals, by tapping their hooves or moving boards bearing letters of the alphabet or numbers, appeared to demonstrate the ability to read, understand a language, recognize people by name, and perform complex mathematical operations. Yet careful examination of the circumstances showed that these were merely automatisms directed by the movements or cues of onlookers, especially those who had trained them. Indeed, when the circumstances were altered, the apparently intelligent actions ceased or became erratic, with constant errors (cf. on this subject: A. Gemelli, *Beasts that Think and Do Arithmetic... and Men Who Do Not Reason*, in *Religion and Science*, Milan 1920, pp. 51-108; id., *The Intelligence of Apes*, in *Science and Apologetics*, 1920, pp. 301-33; E. Claparède, *The Thinking Horses of Elberfeld*, in *Arch. de psychologie*, 12 [1912], p. 203 ff.; 13 [1913], p. 244 ff.; id. and J. Largnier, *On the Mannheim Dog*, ibid., pp. 312-78).
Regarding the entire question of the marvelous feats of these "clever brutes," which seem to presuppose the presence of an intellectual faculty, it must be borne in mind that: (1) the facts must be carefully examined to distinguish the pure truth from the anthropomorphic interpretations with which they are often presented and embellished; (2) the fact must not be unique, so as to exclude purely fortuitous events; (3) an explanation must first be sought in sensory faculties, memory, etc. By rigorously following these principles, one will increasingly observe that what appears to be intelligence is never truly intelligence.
VI. INSTINCT IN MAN
Even in man, being an animal, instincts exist and manifest themselves from earliest infancy. In the child, for instance, one observes the instinct to suckle, to swallow, to move and walk; the gregarious instinct, that is, the impulse to seek the company of others; the instinct of fear at an unexpected sound or the appearance of a stranger; the instinct to turn to the mother and rest quietly in her arms. The child expresses its states of mind through crying, shouting, laughter, smiles, and caresses. Yet man, endowed with intelligence, easily exercises a kind of "censorship" over his instincts, gradually subjecting them to the rule of reason and will, so that they lose their character of "animality" and take on that of inclination (q.v.). Hence it is often said that man has fewer instinctual abilities than animals but more instinctual inclinations. This is why the instincts of man appear fully and often even in abnormal forms in individuals deprived of the use of intelligence, e.g., in imbeciles and cretins; whereas in the normal child they appear in their natural purity.VII. THE LAWS OF INSTINCT
Instincts are subject to certain laws that have important consequences in the field of pedagogy. 1) Law of caducity: many instincts, present and operative in the early years of life, later cease simply as a result of the organism’s development; thus, for example, chicks, after a certain number of days, no longer feel the impulse to take shelter under the hen’s wings when she warns them of danger. 2) Law of specialization: once an instinct has found full satisfaction in a particular object, it tends to become exclusively attached to that object and thus loses its spontaneous impulse toward other objects of the same kind; hence the exclusive love for a place (a bird rebuilding its nest on the same branch), or "irrational" sympathies or antipathies toward certain people or actions. In such cases, instinct tends to transform into an acquired inclination. 3) Law of confusion: if a given object arouses two contradictory instincts, the development of one will result in the inhibition of the other, rendering it latent or dormant. For example, a chick experiences two contradictory impulses: to follow or to flee from a person. If, from the first day, it is habituated to follow that person, it will no longer feel the instinct of fear toward her, which normally arises on the fourth day. 4) Law of survival: if an instinct has been able to function at the time when its dynamism was at its peak, it will leave behind a habit that continues to live and react even after the instinct itself has disappeared. Instincts exercised to the fullest in a particular direction (e.g., the instinct for play or sport) produce a particular attachment to that game or pastime. 5) Law of inhibition: an instinct cannot be neutralized before the period of its natural decline except by the development of a contrary instinct. Thus, the fear of punishment can prevent the development of certain undesirable instincts.VIII. THE PEDAGOGY OF INSTINCT
The laws mentioned above provide the educator with important guidelines that have repercussions throughout life: 1) Instincts must be observed and directed from their first appearance. Therefore, families must keep children under their eyes as much as possible; only thus can they, by noticing bad tendencies, take steps to correct them by removing objects that might serve as stimuli for wrongdoing and instead offering objects that foster good tendencies. Those outside the family rarely perform this duty well, and within the family no one does it better than the mother, whose heart is richest in intuition and affection. 2) Useful tendencies should be watched for so that they may be given continuous opportunity for exercise, with those most beneficial for the future being developed to their highest potential. 3) Everything that might represent a danger—both in the present and for the future—should be kept from the child (e.g., a child’s combativeness should not always be indulged with toy swords, bows and arrows, or anything that smacks of violent domination). 4) Danger must not be confused with pain. Nothing is more effective than associating pleasure and pain with the exercise of instincts, according to whether one wishes to encourage or repress them. The pain that follows or results from the exercise of a harmful action has great inhibitory power. Certainly, the preeminent inhibitory power is the activity of the will, illuminated by the clear reasons provided by intelligence; but even within the sensitive realm, punishment and chastisement admirably support the weakness of the will. 5) The fear of risk and pain should not be exaggerated; otherwise, one will produce inert, selfish, and unfeeling persons, whereas nothing is more educational and formative than the lived experience of pain.Instinct
nann. Inutinkt u. Intelligenz im Tierreich, 3a ed., Friburgo i. Br. 1905 (vers. it., Firenze 1908); P. Hacht-Souplct, La ge-nie des instincts, Parigi 1912; J. H. Fabre, Souvenirs entomolo-giques, 7a ed., 10 voll., Parigi 1919-25, (vers. it., Milano 1922-27); H. E. Ziegler, Der Begriffe des Instintes einst u. jetzt, 3a ed., Jena 1920; J. de la Vassière, Psychologie pédagogique. L'enfant, l'adolescent, le jeune homme, 5a ed., Parigi 1926, pp. 217-20, con ampia bibli., pp. 508-509, 510-11; M. Thomas, L'instinct. Théorie, réalité, 1919; J. V. Uexküll-G. Kriszat, I mondi in-visibili, vers. it., Milano 1936; E. Janssens, L'instinct d'après II. Mac Dougall, Parigi 1938; G. Zunini, I. e sviluppo, in Rev. di filo. neo-scolastica, 30 (1938), pp. 519-33 (con ampia bibli.); P. Siwek, Psychologia metafysica, Roma 1944, pp. 167-77, 228-36; E. Baudin, Corso di psicologia, Firenze 1948, pp. 561-86; A. Gemelli-G. Zunini, Introduzione alla psicologia, 2a ed., Milano 1949, pp. 319-68.