456 Evolution and Modern PhilosopliTj 



of our thoughts ; in other words, it assumes the validity of the 

 principle of causality. If organic species could arise without cause 

 there would be no use in framing hypotheses. Only if we assume 

 the principle of causality, is there a problem to solve. 



Though Darwinism has had a great influence on philosophy con- 

 sidered as a striving after a scientific view of the world, yet here is 

 a point of view — the epistemological — where philosophy is not only 

 independent but reaches beyond any result of natural science. 

 Perhaps it will be said : the powers and functions of organic beings 

 only persist (perhaps^also only arise) when they correspond sufficiently 

 to the conditions under which the struggle of life is to go on. 

 Human thought itself is, then, a variation (or a mutation) which 

 has been able to persist and to survive. Is not, then, the problem 

 of knowledge solved by the evolution hypothesis? Spencer had 

 given an affirmative answer to this question before the appearance 

 of The Origin of Species. For the individual, he said, there is an 

 d> priori, original, basis (or Anlage) for all mental life ; but in the 

 species all powers have developed in reciprocity with external con- 

 ditions. Knowledge is here considered from the practical point of 

 view, as a weapon in the struggle for life, as an "organon" which 

 has been continuously in use for generations. In recent years the 

 economic or pragmatic epistemology, as developed by Avenarius and 

 Mach in Germany, and by James in America, points in the same 

 direction. Science, it is said, only maintains those principles and 

 presuppositions which are necessary to the simplest and clearest 

 orientation in the world of experience. All assumptions which 

 cannot be applied to experience and to practical work, will suc- 

 cessively be eliminated. 



In these views a striking and important application is made of 

 the idea of struggle for life to the development of human thought. 

 Thought must, as all other things in the world, struggle for life. 

 But this whole consideration belongs to psychology, not to the 

 theory of knowledge (epistemology), which is concerned only with 

 the validity of knowledge, not with its historical origin. Every 

 hypothesis to explain the origin of knowledge must submit to cross- 

 examination by the theory of knowledge, because it works with the 

 fundamental forms and principles of human thought. We cannot go 

 further back than these forms and principles, which it is the aim of 

 epistemology to ascertain and for which no further reason can be 

 given ^ 



But there is another side of the problem which is, perhaps, of 



^ The preeent writer, many years ago, in hia Psychology (Copenhagen, 1882; Eng. 

 transl. London, 1891), criticised the evolutionistic treatment of the problem of knowledge 

 iiom the Kantian point of view. 



