Page:Mind (New Series) Volume 6.djvu/221

 ON THE NATUEB OF THE NOTION OP EXTERNALITY. 205 than F, G, D, B, there is still a real need, if thought is to be possible, that the perceptive faculty should always repeat the sequence in the same order. In other words, repetition or routine is an essential condition of thought ; the actual order of the sequence is immaterial, but whatever it may be, it must repeat itself if knowledge is to be possible. We express this briefly in the law : That the same set of causes is always accompanied by the same effect." x " When we scientifically state causes we are really describing the successive stages of a routine of experience." 2 "Cause is scientifically used to denote an antecedent stage in a routine of perceptions." 3 "Change of sense-impression is the proper term for external perception." 4 " Scientific law ... is a brief description in mental shorthand of as wide a range as possible of the sequences of our sense- impressions." 5 Full of errors as is the formula above alluded to, our immediate concern is with only one of these, but that the most important: in upholding which, however, Professor Karl Pearson in justice to him be it said is merely echoing a doctrine first given clear utterance by the truly great Berkeley ; a doctrine, too, that forms an integral part of the causal theory of Kant. There is not any routine of perceptions. In order to the substantiation of this contention in a preliminary manner and in the fewest possible words, it may be pointed out that the cause (essential antecedents) of any physical phenom- enon that comes under our personal observation may itself elude observation by happening before our attention is turned to the series of events in question. In such cases the cause (i.e., what is scientifically reckoned as such) of the phenomenon is entirely absent from the series of actual perceptions : while even in imagination (representation) it is not present to the mind until, at best, after the occur- rence of the effect. According to Professor Karl Pearson's formula, on the other hand, the cause would always have to be sought for among the perceptions which precede or accompany the effect. Nor can the theory be even partially saved by saying that in such cases the representation of the cause is scientifically to be regarded as the actual cause ; unless to mention only the most obvious objection to such a course we are prepared to sacrifice the axiom that "the i The Grammar of Science, pp. 162-163. 2 Op. cit., p. 156. 3 Op. cit., p. 180. * Op. cit., p. 330. 5 Op. cit., p. 135.