The line of demarkation between instinct and reason is a mezzotint, reason being often instinctive, and instinct being as frequently flavoured with judgment, ‘Instinct is usually regarded as a special property of the lower animals, and contrasted with the conscious reason of man. But just as reason may be looked upon as a higher form of the understanding or intellect, and not as something essentially distinct from them, so a closer examination shows that instinct and the conscious understanding do not stand in absolute contrast, but rather in a complex relation, and cannot be sharply marked off from each other.’ It is instinct that urges the bird to build its nest; but when birds whose habit it is to build on the ground learn, on the introduction of cats into the neighbourhood, to change their nesting-places to the tree-tops, intelligence and thought are necessary. The first time Cavy (one of my guinea-pigs) smelled a cat, she was almost scared to death. She jumped back from it as if she had come in contact with a red-hot stove, and screamed and kept on screaming, and shot down under my coat as if she were about to be crucified. After a little while I tried to pull her out, but she refused, and kept hiding. The second time the kitten was presented to her the result was the same. But after two or three days of association, she paid little more attention to it than to the other guinea-pigs. She had never seen a cat before. It was the odour of the carnivore that terrified her, and the effect was purely instinctive. But instinct was soon modified by intelligent experience. (Poor dear little Cavy! I wonder where she is now!)
Both instinct and reason (and one, too, just as much as the other) are absolutely dependent upon processes that are purely mechanical—that is, upon brain processes; and brain processes depend upon brain structure, which is inherited. Hence, reason is, in a certain sense, as truly inherited as instinct is. A being must be born with the particular nervous apparatus by means of which reasoning is carried on, or with the power or disposition to develop this apparatus, or he will never reason. The genius of the partridge in cajoling the passer-by from her nest is called instinct, but it is not more inherited than was the genius of Shakspere. Experience simply calls into being that, whatever it is in each particular being, which is inherited. Sir Isaac Newton took to philosophy and Ole Bull to music not less inevitably than the duck takes to water or the hound to hunting. Reason is, hence, inherited by every man, who has it as truly as his erect posture and plantigrade feet. There is something in the past of all of us and of everything which has determined, and which may be used to account for, everything that to-day exists or happens, even to the style and behaviour of every leaf that flutters in the forest, and to the eccentricities of our opinions and handwritings.
Reason, in the sense in which it is here used, is found feebly in the oyster. Oysters taken from a depth never uncovered by the sea open their shells, lose their water, and quickly perish. But oysters taken from the same depths, if kept where they are occasionally left uncovered for short intervals, learn to keep their shells closed and to live a much longer period out of the water. On the coast of France ‘oyster schools’ exist, where oysters intended for inland cities are educated to keep their shells closed when out of the water in order to enable them to survive the desiccating exposures of the overland journey.[1d] This act of the bivalve is probably the result of something like a vague form of reason. It is an act adapted to the accomplishment of a definite end, and the adapting power is acquired from experience. It is, moreover, reason which in its final analysis does not differ from the reason displayed by the wisest being that thinks. Judgment, forethought, common-sense, inference, ingenuity, genius, reason, and abstract thought, are all exercises of the cognitive or perceptive power of mind, and consist, all of them, in nothing more nor less than the discerning of relations among stimuli. The dog who adopts a cut-off in order to intercept a fleeing hare performs exactly the same kind of intellectual process as the mechanic who erects a windmill in order to divert the energies of the breeze, or the politician who adopts a particular platform to catch votes. ‘A perception is always in its essential nature what logicians term a conclusion, whether it has reference to the simplest memory of the past sensation or to the highest product of abstract thought. For, when the highest product of abstract thought is analysed, the ultimate elements must always be found to consist in material given directly by the senses; and every stage in the symbolic construction of ideas, in which the process of abstraction consists, depends on acts of perception taking place in the lower stages’.[5b]
The difference among the perceptive acts of different individuals consists, not in the different kinds of intellectual exercise, but in differences among the materials with which the perceptive faculty deals. There are perceptions of simple sensations, and there are perceptions of composite sensations, or concepts—perceptions of elementary relations, and perceptions of compound and elaborate relations. But all displays of rational faculty, from the simple judgment of distance by the dimness and distinctness of definition and the size of the visual angle, which all higher animals are compelled to make, to the labyrinthic abstractions of the logician, consist in nothing in addition to discriminations among stimuli.
Brehm one day gave one of his apes a paper bag with a lump of sugar and a wasp in it. The ape in getting the sugar was stung by the wasp. From that day, whenever Brehm gave that ape, or any other ape in that cage, a paper package, the animal, before opening it, took the precaution to shake the package at his ear and listen to find out whether or not there was a wasp inside.[7]
Now, such an act of intelligence implies several inferences. A train of thoughts something like this must have passed through this ape’s mind: ‘Now, if one wasp can sting, so can another; and, if a man can deceive me once by wrapping a wasp in a paper with a lump of sugar, he may try it again; and, if one man will attempt such a thing, so may another; and, if men will attempt it on me, they may attempt it on my friends; so I will warn my friends to look out for those villainous chaps outside.’ These inferences of the ape are the same kind of generalisations exactly as are made by men everywhere in their daily lives. And the common-sense inferences made by ordinary people in their every-day affairs are precisely the same processes of reasoning as those used by scientists and philosophers. Many people, like the character in Moliere’s plays who was surprised and delighted to learn that he had been talking prose all his life, are surprised on hearing for the first time that they use induction and deduction every hour almost of their waking lives. They imagine that philosophers must have some secret and superior way of acquiring their conclusions, different from what ordinary mortals have. ‘But there is no more difference,’ says Huxley, ‘between the mental operations of a man of science and those of an ordinary person than there is between the operations and methods of a grocer weighing out his goods in common scales and the operations of a chemist in performing a difficult and complex analysis by means of his balance and finely graduated weights. It is not that the scales in the one case and the balances in the other differ in the principles of their construction or manner of working; but the beam of the one is set on an infinitely finer axis than the other, and, of course, turns by the addition of a much smaller weight’.[8] And the difference in mental method between the man of learning and the ordinary man or woman is the same as the difference between mature men and children and between men generally and other animals. It is one of degree, not of kind. The philosopher, the clodhopper, and the ape, all use precisely the same methods of reasoning, differing only in exactness and in the materials of consciousness dealt with.
Nearly all animals, from mollusks to men, reason—not once or twice in a lifetime, but the most of them every day and every hour of their existence. In fact, it would be impossible for any animal addicted to moving about, and with a delicate and easily wrecked organism, to long survive in a world like this without that elasticity of action which reason alone can impart. Since they live in the same world-conditions as human beings, and are seeking providence for substantially the same wants, non-human beings manifest reason in the same general directions as human beings do—in the location and construction of their homes and fortresses, in the arrest of their prey, in circumventing their enemies, in overcoming obstacles and surmounting dangers, in protecting and educating their young, in meeting the emergencies of food and climate, in the wooing of mates and the waging of wars, and in the thousand other cases where they are called upon in their daily wanderings and doings to deal with novel and unprecedented situations.
When wild geese are feeding there is said to be always one of them that acts as sentinel. This one never takes a grain of corn while on duty. When it has acted awhile it gives the bird next to it a sharp peck and utters a querulous kind of cry, and the second one takes its turn. This is prudence, or forethought, which is a form of reason. When swans are diving there is generally one that stays above the water and watches. Sentinels have alarm sounds of various kinds, which they give to signify ‘enemy.’ ‘Ibex, marmots, and mountain-sheep whistle; prariedogs bark; elephants trumpet; wild geese and swans have a kind of bugle call; rabbits and sheep stamp on the ground; crows caw: and wild ducks utter a low, warning quack.’
In the Popular Science Monthly for March, 1901, is an account of a series of experiments on the intelligence of the turtle made by Professor Yerkes, of Harvard. The turtle was placed in a labyrinth, at the farther end of which was a comfortable bed of sand. It took just thirty-five minutes of wandering for the turtle to reach the nest the first time. But in the second trial the nest was reached in fifteen minutes, and by the tenth trip the turtle was familiar enough with the route to go through in three and one-half minutes, making but two mistakes. The turtle was afterwards placed in a more complex labyrinth, containing, among other features, a blind alley and two inclines. The inclines were puzzles, and it took one hour and thirty-five minutes of aimless rambling for the wanderer to reach its nest the first time. But the fifth trip was made in sixteen minutes, and the tenth in four minutes, which was not far from direct.
These experiments show that animals of almost proverbial density may learn with surprising quickness. English sparrows and other avian inhabitants of the city learn to live tranquilly along the busiest thoroughfares, exposed to all sorts of dangers, and subjected to what would be to many birds the most terrifying circumstances. Whizzing trolleys, tramping multitudes, and screaming engines have no terrors for them. They simply exercise the caution necessary to keep from being run over. They boldly build their nests right under passing elevated cars, where the roar is sufficient to scare the life out of an ordinary country bird. I have seen these testy little chaps sit and feed and jabber to each other in a perfectly unconcerned way within ten or fifteen feet of a thundering express train. They do not do these things from instinct: they learn to do them. They know that a diabolical-looking locomotive is harmless, because they have seen it before; and they know that an insignificant urchin with a savage heart and a sling is not harmless, and they know it simply because they have previously had dealings with him. English sparrows will disappear completely from a neighborhood if a few of them are killed. Cats, dogs, horses—all animals, in fact—acquire during life a fund of information as to how to act in order to avoid harm and extinction. If they did not, they would not live long. And they do it just as man does it, by memory and discrimination, by retaining impressions made upon them, and acting differently when an impression is made a second, third, or thirteenth time.