§ 5. Causality as Ideal Construction. — On the purely perceptual level, there is a tendency to repeat modes of procedure which have proved successful in the past, and to discontinue modes of procedure which have proved unsuccessful. To this extent, the category of causality operates in perceptual consciousness. But for the merely perceptual consciousness the question why a given course produces a given effect has no existence. Ideal construction is continually asking this question. It is the very essence of the process by which means are devised for the attainment of practical ends to interpose between the startingpoint and its termination a series of ideally represented links, each constituting an indispensable term in a train of causes leading up to the ultimate effect. These practical experiences yield material for interpreting events which take place apart from the agency of the subject. Thus it becomes possible to ask why A produces D, and to answer by saying that A produces B, and that B produces C, and that C produces D. So far as this ideal construction is determined by more or less practical experiences such as those connected with mechanical contrivance, it yields a true insight into the nature of physical process. But strong interests of a practical or theoretical kind often create a need for explanation where data for explanation are either altogether insufficient or absent. In such cases the ideal construction will take a form which appears from a higher point of view fanciful and absurd. Why has the robin a red breast? Because cocksparrow shot it with his bow and arrow. A good example of a simple causal series of this kind is the story of the old woman whose pig would not go over the stile. "As soon as the cat had lapped up the milk, the cat began to kill the rat, the rat began to gnaw the rope, the rope began to hang the butcher, the butcher began to kill the ox, the ox began to drink the water, the water began to quench the fire, the fire began to burn the stick, the stick began to beat the dog, the dog began to bite the pig, the pig in a fright jumped over the stile, and so the old woman got home that night." In savage thought, there are abundant examples of causal explanation which remind us of these nursery fables.

The word why may have another application. In asking why a given effect is produced, the interest may lie in discovering which of a given group of conditions are essential to the result, and which irrelevant. This inquiry naturally arises when the same result follows under circumstances apparently dissimilar on the whole, or fails to appear under circumstances apparently similar on the whole. To find a cause is here to find points of identity in apparently dissimilar conditions, and of difference in apparently similar conditions. There is a West African story according to which a hunter took the first hint for weaving nets from contemplating the spider's web. His wife suggested that he might make mats and similar articles in like manner. He tried, but failed to give them shape. Accordingly, he went back to observe the procedure of the spider, so as to note the points of difference between the animal's method and his own. He discovered that the spider started always with a fixed framework and wove its web on that. Going back to his own task, he made for himself a framework by means of sticks and poles, and so succeeded in giving proper shape to the articles he made. He had compared the two modes of procedure, so as to distinguish the points of agreement from the points of difference, and in this way was able to explain why a certain result should follow in the one case, and a different result in the other. It is by such processes of analytic comparison that universal laws of nature are ultimately discovered, which laws may form the basis of such exact and complicated mechanical contrivances as the steamengine or the electric telegraph. In early stages of development, the distinction of the essential part of a cause from the accidental is very crude and irrelevant, and is in the main proportioned to the degree of advancement in the mechanical arts. Arsenic and incantations, according to Voltaire, will kill a flock of sheep. The savage never thinks of using the arsenic without the incantations. The medicine man accompanies even surgical operations with all kinds of ceremonials having nothing to do with the result. In Charles Lamb's dissertation on roast pig, we have a fanciful exaggeration of this feature of savage thought. Bobo discovers the flavour of roast pig by accidentally setting fire to a house. The custom of firing houses in order to roast pigs continued "till in process of time . . . a sage arose, like our Locke, who made a discovery that the flesh of swine, or indeed of any other animal, might be cooked (burnt, as they called it) without the necessity of consuming a whole house to dress it."* The exaggeration in Lamb's story arises from his having chosen a case in which all essential conditions fall within the practical experience and control of the agents interested in the result, so that it would be easy for them to disengage the essential from the accidental. He would scarcely have exaggerated if he had chosen such natural phenomena as disease and death, in which the operative conditions are in the main beyond the control and even beyond the ken of the uncultured mind. Here ideal construction cannot fix upon what is essential; and since the strength of the practical interests concerned demands the discovery of some operative conditions to form a basis of practical procedure, causal efficacy is ascribed to all kinds of circumstances which are in reality totally irrelevant, such as the evil eye, the malignancy of departed spirits, the magical practices of witches, and the like. On these assumptions, elaborate methods of procedure are based. Such methods are often more or less intermingled with truly curative measures, which prevent the result being wholly a matter of accident. But on the whole, much more stress is laid on what is irrelevant and inefficient, than on what is relevant and efficient. In treating a disease, it is obvious that the cure does not depend merely on drugs, or the like; for the patient may either die or recover when the same drugs are used. Other conditions are therefore imagined which by their very nature cannot come except in a partial and uncertain way within the control of the medicine man.