Page:Mind (Old Series) Volume 12.djvu/566

 PLACE OF HYPOTHESIS IN EXPERIMENTAL SCIENCE. 553 are necessary elements in causation, we define cause as the totality of the conditions which given a phenomenon invari- ably occurs, which not given it as invariably does not occur, we have to ask what we mean by ' totality of conditions '. The phrase may mean either the totality of the pheno- menal or sensible conditions of a phenomenon, or the totality of its conditions, insensible as well as sensible. Only in the former sense can the totality of the conditions of a pheno- menon be ascertained by observation and experiment; but in this limited sense the conditions of a phenomenon are merely so many particular facts, and the fullest account which could be given of them would amount to no more than a descrip- tion of the phenomenon, its concomitants and antecedents. On the other hand, the causes with which science is con- cerned are, as I shall show in the sequel, always insensible, the laws which it formulates always hypothetical. If, how- ever, the expression ' totality of conditions ' is to include the insensible as well as the sensible conditions of phenomena, it is too wide for practical utility, since the absolute totality of the conditions which determine a phenomenon is only know- able by omniscience. Whatever scientific men mean by cause, they mean neither the empirically uniform antecedents and concomitants of a phenomenon nor the totality of its conditions : they mean more than the one and less than the other. What then, the reader may ask with some impatience, do you say that they mean ? I answer : the distinction between cause and effect is simply one mode of the distinction between the real and the apparent. Physics starts with the postulate that the observed order is not the real order. It regards sensible appearances and their empirically uniform interconnexions as merely indices of a real order, which can only be apprehended by means of the exercise of a faculty which may with indifference be called reason or scientific imagination. Such a conception is implied in the mere use of the terms object and objective, and, as object and subject are correlative, is based upon the rock of self-consciousness. What the object or substance is to a group of sensible per- ceptions, that the cause is to an event or sequence of events. Physical science is an attempt to give precision to that con- ception of the world, as other than that which it appears, which is implicit in ordinary experience, and for this purpose its chief instrument is hypothesis. Observation and experi- ment are indeed indispensable, but only for the purpose of furnishing hypothesis with correct data and testing the adequacy, or, as Lewes well said, the " effectiveness," of a 36