The great physiologist Müller and the great philosopher Hegel are quoted by Mr. Mivart as maintaining, that “to form abstract conceptions of such operations as of something common to many under the notion of cause and effect, is a perfect impossibility to them” (animals[49]); and no doubt many other illustrious names might be quoted in support of the same statement. But it seems to me that needless obscurity is imported into this matter, by not considering in what our own idea of causality consists. It is clear that to attain a general idea of causality as universal, &c., demands higher powers of abstract thought than are possessed by any animals, or even by the great majority of men; but it is no less clear that all men and most animals have a generic idea of causality, in the sense of expecting uniform experience under uniform conditions. A cat sees a man knock at the knocker of a door, and observes that the door is afterwards opened: remembering this, when she herself wants to get in at that door, she jumps at the knocker, and waits for the door to be opened.[50] Now, can it be denied that in this act of inference, or imitation, or whatever name we choose to call it, the cat perceives such an association between the knocking and the opening as to feel that the former as antecedent was in some way required to determine the latter as consequent? And what is this but such a perception of causal relation as is shown by a child who blows upon a watch to open the case—thinking this to be the cause of the opening from the uniform deception practised by its parent,—or of the savage who plants nails and gunpowder to make them grow? And endless illustrations of such a perception of causality might be drawn from the everyday life of civilized man: indeed, how seldom does any one of us wait to construct a general proposition about causality in the abstract before we act on our practical knowledge of it. And that this practical knowledge in the case of animals enables them to form a generic idea, or recept, of the equivalency between causes and effects—such that a perceived equivalency is recognized by them as an explanation—would appear to be rendered evident by the following fact, which I carefully observed for the express purpose of testing the question. I quote the incident from an already-published lecture, which was given before the British Association at Dublin, in 1878.
“I had a setter dog which was greatly afraid of thunder. One day a number of apples were being shot upon the wooden floor of an apple-room, and, as each bag of apples was shot, it produced through the rest of the house a noise resembling that of distant thunder. My dog became terror-stricken at the sound; but as soon as I brought him to the apple-room and showed him the true cause of the noise, he became again buoyant and cheerful as usual.”[51]
The importance of clearly perceiving that animals have a generic, as distinguished from an abstract, idea of causation—and, indeed, must have such an idea if they are in any way at all to adjust their actions to their circumstances—the importance of clearly perceiving this is, that it carries with it a proof of the logic of recepts being able to reach generic ideas of principles, as well as of objects, qualities, and actions. In order to prove this important fact still more unquestionably, I will here quote a passage from the biography of the cebus which I kept for the express purpose of observing his intelligence.
“To-day he obtained possession of a hearth-brush, one of the kind which has the handle screwed into the brush. He soon found the way to unscrew the handle, and, having done that, he immediately began to try to find out the way to screw it in again. This he in time accomplished. At first he put the wrong end of the handle into the hole, but turned it round and round the right way for screwing. Finding it did not hold, he turned the other end of the handle, carefully stuck it into the hole, and began again to turn it the right way. It was, of course, a very difficult feat for him to perform, for he required both his hands to hold the handle in the proper position, and to turn it between his hands in order to screw it in; and the long bristles of the brush prevented it from remaining steady, or with the right side up. He held the brush with his hind hands, but even so it was very difficult for him to get the first turn of the screw to fit into the thread; he worked at it, however, with the most unwearying perseverance until he got the first turn of the screw to catch, and he then quickly turned it round and round until it was screwed up to the end. The most remarkable thing was that, however often he was disappointed in the beginning, he never was induced to try turning the handle the wrong way; he always screwed it from right to left. As soon as he had accomplished his wish, he unscrewed it again, and then screwed it on again the second time rather more easily than the first, and so on many times.”
The above is extracted from the diary kept by my sister. I did not myself witness the progress of this research with the hearth-brush, as I did so many of the other investigations successfully pursued by that wonderful animal. But I have a perfect confidence in the accuracy of my sister’s observation, as well as in the fidelity of her account; and, moreover, the point with which I am about to be concerned has reference to what followed subsequently, as to which I had abundant opportunities for close and repeated observations. For the point is that, after having thus discovered the mechanical principle of the screw in that one particular case, the monkey forthwith proceeded to generalize, or to apply his newly gained knowledge to every other case where it was at all probable that the mechanical principle in question was to be met with. The consequence was that the animal became a nuisance in the house by incessantly unscrewing the tops of fire-irons, bell-handles, &c., &c., which he was by no means careful always to replace. Here, therefore, I think we have unquestionable evidence of intelligent recognition of a principle, which in the first instance was discovered by “the most unwearying perseverance” in the way of experiment, and afterwards sought for in multitudes of wholly dissimilar objects.[52]
To these numerous facts I will now add one other, which is sufficiently remarkable to deserve republication for its own sake. I quote the account from the journal Science, in which it appeared anonymously. But finding on inquiry that the observer was Mr. S. P. Langley, the well-known astronomer, and being personally assured by him that he is certain there is no mistake about the observation, I will now give the latter in his own words.
“The interesting description by Mr. Larkin (Science, No. 58) of the lifting by a spider of a large beetle to its nest, reminds me of quite another device by which I once saw a minute spider (hardly larger than the head of a pin) lift a house-fly, which must have been more than twenty times its weight, through a distance of over a foot. The fly dangled by a single strand from the cross-bar of a window-sash, and, when it first caught my attention, was being raised through successive small distances of something like a tenth of an inch each; the lifts following each other so fast, that the ascent seemed almost continuous. It was evident that the weight must have been quite beyond the spider’s power to stir by a ‘dead lift;’ but his motions were so quick, that at first it was difficult to see how this apparently impossible task was being accomplished. I shall have to resort to an illustration to explain it; for the complexity of the scheme seems to belong less to what we ordinarily call instinct than to intelligence, and that in a degree we cannot all boast ourselves.
“The little spider proceeded as follows:—