October 7, 1922] 



NA TURE 



47i 



The New Way of Thinking Physical 

 Reality. 



(1) The Philosophy of Humanism and of other Subjects. 

 By Viscount Haldane. Pp. xiv + 302. (London: 

 J. Murray, 1922.) 125. net. 



(2) UExpSrience humaine et la causaliU physique. Par 

 Prof. Leon Brunschvicg. (Bibliotheque de Philo- 

 sophic Contemporaine.) Pp. xvi + 625. (Paris: 

 Felix Alcan, 1922.) 30 frs. 



(3) La Notion d'espace. Par Prof. D. Nys. (Fonda- 

 tion Universitaire de Belgique.) Pp. 446. (Bruxelles: 

 Robert Sand ; London : Oxford University Press, 

 1922.) 15s'. net. 



(4) The Evolution of Knoivledge. By George Shann. 

 Pp. vii + 100. (London : Longmans, Green and Co., 

 1922.) 45. 6d. net. 



THE direction which scientific research has taken 

 in the twentieth century is imposing on 

 philosophy a task the magnitude of which is probably 

 not yet realised by any one. Aristotle, in his doctrine 

 of the four causes and in his discovery of the syllogism, 

 the logical instrument which gave that doctrine the 

 appearance of precision, determined the type and the 

 mode to which all succeeding scientific research right 

 up to modern times has adhered. The essential thing 

 in the Aristotelian doctrine is that the analysis of the 

 physical universe proceeds in precisely the same way 

 as the analysis of the elementary conditions which 

 govern the production of a work of art. There is, that 

 is to say, a matter on which an agent impresses a form 

 in order to express an end or purpose. The modern 

 sciences of biology and psychology had already begun 

 to undermine this aesthetic mode of thinking reality 

 and now the Einstein theory in mathematical physics 

 has swept away its foundations. The result is that 

 once more in human history physics and metaphysics 

 are joined together. The union has been brought 

 about by physical science itself, without any betrayal 

 of its positive and experimental character, by fearless 

 acceptance of the apparently paradoxical results of 

 experiments. It is the outcome, we can now see, of a 

 historical progress of pure science in the last three 

 centuries, continuous in its development from Galileo 

 to Clerk Maxwell, Mach and Einstein, which has led 

 to a complete revolution in the way of thinking 

 physical reality. 



The philosophical current of human thought, 

 although always a reflection of the scientific current, 

 has not the same rhythm. It happens at times, un- 

 expectedly and as if by a sudden explosion, that the 

 scientific current is interrupted ; some wholly unlooked- 

 for results of experimental investigation have occurred, 

 NO. 2762, VOL. I IO] 



and the human mind has sprung at once to the general 

 principles whence those results proceed. A new vision 

 of truth then opens out before human consciousness 

 involving its whole conception of the universe and mind. 

 It was such a vision which produced the new birth of 

 modern philosophy in the seventeenth century. To- 

 day a new and most startling discovery, following 

 indeed a long historical development, but a develop- 

 ment we can appreciate only now because the discovery 

 has given us the vantage ground from which to look 

 back on the history, is opening to us a new vision of 

 truth and making us rethink our whole concept of the 

 nature of physical reality. 



(1) and (2) It is this new way of thinking physical 

 reality which, each in his own way, the authors we have 

 grouped together are seeking to express. In the case of 

 Lord Haldane's " Humanism " and Prof. Brunschvicg's 

 " L'Experience humaine " there is full consciousness of 

 it and a direct purpose of exposition. It is noteworthy 

 that two such books, widely different in their method 

 and scope and yet so singularly in agreement, both in 

 their viewpoint and aim, should appear together. 

 Lord Haldane, who is not a mathematician, devotes 

 himself to detailed philosophical analysis of the new 

 mathematical concept, while Prof. Brunschvicg, a 

 mathematician of distinction and known to us chiefly 

 by his editio princeps of Pascal's works, traces with an 

 extraordinary grasp of details the historical develop- 

 ment of the concept of physical causality which has 

 resulted in the generalised theory of relativity ; and 

 both interpret to us the new concept of the physical 

 universe in practically identical terms. The humanism 

 of the one is the human experience of the other, and 

 Lord Haldane's " foundational nature of knowledge " 

 is Prof. Brunschvicg's " philosophie de la pensee." 



The cosmology of Einstein differs fundamentally 

 from every previous doctrine inasmuch as it discards 

 both the factors which in the long history of human 

 thought have contended against one another for pre- 

 eminence. It regards neither the definition of the 

 concept, whence deduction is made, nor the datum of 

 experience, on which induction is based, as funda- 

 mental. Einstein's world is a world of figures, sup- 

 posing neither a priori concepts nor sensible images. 

 These figures, however, are not fictions, they are not 

 even abstractions, they correspond to coefficients 

 which reality furnishes. Mathematics determines for 

 us the invariant which passes from one system to 

 another. 



Between Newton and Einstein, Prof. Brunschvicg 

 tells us, there is this difference that according to Newton 

 the thing to be measured has an absolute content, 

 inaccessible it may be directly to man, but certainly 

 accessible to God. That is to say, the Newtonian 



