Tendency of the mind to search for causes, and the necessity for their discovery.
When we contemplate the seemingly infinite variety, the endless succession, of events that pass under our observation in what we call the external world, we are led by an irresistible tendency to trace what we call a causal connexion between them. The tendency to discover the causes of things appears indeed to be innate in the constitution of our minds and indispensable to our continued existence. It is the link that arrests and colligates into convenient bundles the mass of particulars drifting pell-mell past on the stream of sensation; it is the cement that binds into an edifice seemingly of adamant the loose sand of isolated perceptions. Deprived of the knowledge which this tendency procures for us we should be powerless to foresee the succession of phenomena and so to adapt ourselves to it. We should be bewildered by the apparent disorder and confusion of everything, we should toss on a sea without a rudder, we should wander in an endless maze without a clue, and finding no way out of it, or, in plain words, unable to avoid a single one of the dangers which menace us at every turn, we should inevitably perish. Accordingly the propensity to search for causes is characteristic of man in all ages and at all levels of culture, though without doubt it is far more highly developed in civilised than in savage communities. Among savages it is more or less unconscious and instinctive; among civilised men it is deliberately cultivated and rewarded at least by the applause of their fellows, by the dignity, if not by the more solid recompenses, of learning. Indeed as civilisation progresses the enquiry into causes tends to absorb more and more of the highest intellectual energies of a people; and an ever greater number of men, renouncing the bustle, the pleasures, and the ambitions of an active life, devote themselves exclusively to the pursuit of abstract truth; they set themselves to discover the causes of things, to trace the regularity and order that may be supposed to underlie the seemingly irregular, confused, and arbitrary sequence of phenomena. Unquestionably the progress of civilisation owes much to the sustained efforts of such men, and if of late years and within our own memory the pace of progress has sensibly quickened, we shall perhaps not err in supposing that some part at least of the acceleration may be accounted for by an increase in the number of lifelong students.
The idea of cause is simply that of invariable sequence suggested by the observation of many particular cases of sequence.
Now when we analyse the conception of a cause to the bottom, we find as the last residuum in our crucible nothing but what Hume found there long ago, and that is simply the idea of invariable sequence. Whenever we say that something is the cause of something else, all that we really mean is that the latter is invariably preceded by the former, so that whenever we find the second, which we call the effect, we may infer that the first, which we call the cause, has gone before it. All such inferences from effects to causes are based on experience; having observed a certain sequence of events a certain number of times, we conclude that the events are so conjoined that the latter cannot occur without the previous occurrence of the former. A single case of two events following each other could not of itself suggest that the one event is the cause of the other, since there is no necessary link between them in the mind; the sequence has to be repeated more or less frequently before we infer a causal connexion between the two; and this inference rests simply on that association of ideas which is established in our mind by the reiterated observation of the things. Once the ideas are by dint of repetition firmly welded together, the one by sheer force of habit calls up the other, and we say that the two things which are represented by those ideas stand to each other in the relation of cause and effect. The notion of causality is in short only one particular case of the association of ideas. Thus all reasoning as to causes implies previous observation: we reason from the observed to the unobserved, from the known to the unknown; and the wider the range of our observation and knowledge, the greater the probability that our reasoning will be correct.
The savage draws his ideas of natural causation from observation of himself. Hence he explains the phenomena of nature by supposing that they are produced by beings like himself. These beings may be called spirits or gods of nature to distinguish them from living human gods.
All this is as true of the savage as of the civilised man. He too argues, and indeed can only argue on the basis of experience from the known to the unknown, from the observed to the hypothetical. But the range of his experience is comparatively narrow, and accordingly his inferences from it often appear to civilised men, with their wider knowledge, to be palpably false and absurd. This holds good most obviously in regard to his observation of external nature. While he often knows a good deal about the natural objects, whether animals, plants, or inanimate things, on which he is immediately dependent for his subsistence, the extent of country with which he is acquainted is commonly but small, and he has little or no opportunity of correcting the conclusions which he bases on his observation of it by a comparison with other parts of the world. But if he knows little of the outer world, he is necessarily somewhat better acquainted with his own inner life, with his sensations and ideas, his emotions, appetites, and desires. Accordingly it is natural enough that when he seeks to discover the causes of events in the external world, he should, arguing from experience, imagine that they are produced by the actions of invisible beings like himself, who behind the veil of nature pull the strings that set the vast machinery in motion. For example, he knows by experience that he can make sparks fly by knocking two flints against each other; what more natural, therefore, than that he should imagine the great sparks which we call lightning to be made in the same way by somebody up aloft, and that when he finds chipped flints on the ground he should take them for thunder-stones dropped by the maker of thunder and lightning from the clouds?3 Thus arguing from his limited experience primitive man creates a multitude of spirits or gods in his own likeness to explain the succession of phenomena in nature of whose true causes he is ignorant; in short he personifies the phenomena as powerful anthropomorphic spirits, and believing himself to be more or less dependent on their good will he woos their favour by prayer and sacrifice. This personification of the various aspects of external nature is one of the most fruitful sources of polytheism. The spirits and gods created by this train of thought may be called spirits and gods of nature to distinguish them from the human gods, by which I mean the living men and women who are believed by their worshippers to be inspired or possessed by a divine spirit.
In time men reject polytheism as an explanation of natural processes and substitute certain abstract ideas of ethers, atoms, molecules, and so on.
But as time goes on and men learn more about nature, they commonly become dissatisfied with polytheism as an explanation of the world and gradually discard it. From one department of nature after another the gods are reluctantly or contemptuously dismissed and their provinces committed to the care of certain abstract ideas of ethers, atoms, molecules, and so forth, which, though just as imperceptible to human senses as their divine predecessors, are judged by prevailing opinion to discharge their duties with greater regularity and despatch, and are accordingly firmly installed on the vacant thrones amid the general applause of the more enlightened portion of mankind. Thus instead of being peopled with a noisy bustling crowd of full-blooded and picturesque deities, clothed in the graceful form and animated with the warm passions of humanity, the universe outside the narrow circle of our consciousness is now conceived as absolutely silent, colourless, and deserted. The cheerful sounds which we hear, the bright hues which we see, have no existence, we are told, in the external world: the voices of friends, the harmonies of music, the chime of falling waters, the solemn roll of ocean, the silver splendour of the moon, the golden glories of sunset, the verdure of summer woods, and the hectic tints of autumn—all these subsist only in our own minds, and if we imagine them to have any reality elsewhere, we deceive ourselves. In fact the whole external world as perceived by us is one great illusion: if we gave the reins to fancy we might call it a mirage, a piece of witchery, conjured up by the spells of some unknown magician to bewilder poor ignorant