We have now noticed the chief characteristics of instinct: its existence prior to all experience or instruction; its incapacity of improvement, except within the narrow sphere of domestication; its limitation to a few objects, and the certainty of its action within these limits; the distinctness and permanence of its character for each species; and its constant hereditary nature. In regard to the uniformity of instinct throughout each species, it may be further remarked, that this seems to be very constantly preserved in the lowest divisions of the animal kingdom. Among the Articulates, also, instinct appears almost unvarying; and it is in this department among the insect tribes that the most striking manifestations of instinct are to be met with. When we arrive among the higher orders of the Vertebrates, we find in some species that each individual is capable of some modification of its actions, according to the particular circumstances in which it finds itself placed. But throughout the long series of animals, from the polype to man, there is instinctive action more or less in amount in every species, with, perhaps, the exception of man alone. The variety of that endowment, which is adapted to definite objects, means, and results, in each particular one of the five hundred thousand species estimated to be now living, may well call forth our admiration and astonishment at the magnitude and extent of the prospective contrivance of the Creator. How various the relations of all these animals to each other and to the inanimate world about them! and yet how admirable the adjustments of that immaterial principle which regulates their lives, so as to secure the well-being of each and the symmetry of the general plan!
There has been much diversity of opinion as to the existence of instincts in the human species,—some making the whole mind of man nothing but a bundle of instincts, and others wholly denying him any endowment of this nature, while others still have given him a complex mental nature, and have, moreover, declared that intellect and instinct in him are so interwoven that it is impossible to tell where the one begins and the other ends. But we believe, with the author of "Ancient Metaphysics," that in Nature, however intimately things are blended together and run into each other like different shades of the same color, the species of things are absolutely distinct, and that there are certain fixed boundaries which separate them, however difficult it may be for us to find them out. In regard to intelligence and instinct, the two principles seem to us to be not more distinctly and widely separated in their nature than in the provinces of their operation.
Sir Henry Holland, who believes that intelligence and instinct are blended in man, admits that instincts, properly so called, form the minimum in relation to reason, and are difficult of definition from their connection with his higher mental functions, but that, wherever we can truly distinguish them, they are the same in principle and manner of operation as those of other animals. He makes one distinction, however, between the instincts of man and those of lower animals,—that in the former they have more of individual character, are far less numerous and definite in relation to the physical conditions of life, and more various and extensive in regard to his moral nature. But, on the other hand, Sir B.C. Brodie seems to be of opinion that the majority of instincts belonging to man resemble those of the inferior animals, inasmuch as they relate to the preservation of the individual and the continuation of the species; and that when man first began to exist, and for some generations afterwards, the range of his instincts was much more extensive than it is at the present time. When authorities so eminent as these differ so widely upon the question, to what human instincts relate, we see at least that it is very difficult to define and distinguish these instincts, and we may be led to doubt their existence at all. Of that marvellous endowment which guides the bee to fabricate its cells according to laws of the most rigid mathematical exactness, and guides the swallow in its long flight to its winter home, we agree with Professor Bowen, that there is no trace whatever in human nature. The actions of man which have been loosely described as instinctive belong for the most part to those classes of actions which we have already shown to be in no proper sense of the word instinctive, that is, those concerned in the appetites and in the functions of organic life. There are also numerous automatic and habitual actions which are liable to be mistaken for instincts. Some have included in the category of instincts those intuitive perceptions and primary beliefs which are a part of our constitution, and are the foundation of all our knowledge. But these propensities of thought and feeling are of a higher nature than mere instincts; they are immutable laws of the human mind, which time and physical changes cannot reach: they do not seem to depend upon the physical organization, but to be inherent in the soul itself. If these are instincts, then, why are not all the ways in which the mind exerts itself instincts also, and reason itself an instinct?
There is hardly any human action, feeling, or belief, which has not been ranged under the term instinct. Hunger and thirst have been called instincts; so have the faculty of speech, the use of the right hand in preference to the left, the love of society, the desire to possess property, the desire to avoid danger and prolong life, and the belief in supernatural agencies, upon which is engrafted the religious sentiment. We cannot, in this paper, attempt to analyze these and many other similar examples which have been given as illustrations of instinct in treatises of high repute, and show that they do not at all come within that class of actions which we contrast with reason. In regard to those actions of early infancy which have often been adduced as illustrations of instinct, the physiologists of the present day are agreed that they are as mechanical as the act of breathing. To place these upon the same level with the complex and wonderful operations of the bee, the ant, and the beaver, is to admit that the instincts of the latter are merely reflex actions following impressions on the nerves of sense.
On the other hand, whether the animals inferior to man ever exercise any conscious process of reasoning is a question which has often been discussed, and upon which there is no general agreement. Instances of the remarkable sagacity of some domesticated animals are often adduced as proofs of reasoning on their part. Some of these wonderful feats may be traced to the unconscious faculty of imitation, which even in man often appears as a blind propensity, although he exercises an active and rational imitation as well. Sometimes the mere association of ideas, or the perception by animals that one thing is accompanied by another or that one event follows another, is mistaken for that higher principle which in man judges, reflects, and understands causes and effects. When the dog sees his master take down his gun, his blandishments show that he anticipates a renewal of the pleasures of the chase. He does not reflect upon past pleasures; but, seeing the gun in his master's hand, a confused idea of the feelings that were associated with the gun in times past is called up. So the ox and the horse learn to associate certain movements with the voice and gesture of man. And so a fish, about the most stupid of all animals, comes to a certain spot at a certain signal to be fed. These combinations are quite elementary. This is quite another thing from that reciprocal action of ideas on each other by which man perceives the relations of things, understands the laws of cause and effect, and not only forms judgments of the past, but draws conclusions which are laws for the future. We find in the brute no power of attending to and arranging its thoughts,—no power of calling up the past at will and reflecting upon it. The animal has the faculty of memory, and, when this is awakened, the object remembered may be accompanied by a train or attendance of accessory notions which have been connected with the object in the animal's past experience. But it never seems to be able to exercise the purely voluntary act of recollection. It is not capable of comparing one thing with another, so far as we can judge. If the animal could exercise any true act of comparison, there would be no limit to the exercise of it, and the animal would be an intelligent being; for the result of a simple act of comparison is judgment, and reasoning is only a double act of comparison. We have the authority of Sir William Hamilton for saying that the highest function of mind is nothing higher than comparison. Hence comes thought,—hence,