178 PRESENT-DAY RATIONALISM 



basis ; and the very suggestion of any alternative is quite un- 

 thinkable. 



When, however, we turn to Nature and try to discover how 

 Evolution has come about ; that is to say, how and under what 

 circumstances, variations of structure make their appearance, 

 become fixed, and so give rise to new varieties and species, we 

 have the two alternatives which Darwin laid before us — Adap- 

 tation and Natural Selection. 



The former is based on as innumerable a supply of facts 

 as Evolution itself, because, as we have seen, it lies at the 

 foundation of Evolution or may be said to be identical with it. 

 Given the responsive power of protoplasm and some new con- 

 ditions of life — Evolution is the result. 



On the other hand, Natural Selection is based on two as- 

 smnptions : (i) that individual differences give rise to variations 

 of a sufficient amount and constancy to have a selective value ; 

 (2) that when new conditions of life are present, the offspring 

 vary indefinitely. On these two hypothetical "axioms" 

 Natural Selection was considered as solving all problems in the 

 organic world, including man and his psychological phenomena, 

 and even to include death ! 



Natural Selection is thus quite comparable to the numerous 

 "final causes" or "designs" of the older teleologists' a priori 

 assumptions without an inductive basis — they easily explained 

 everything by assuming that it was "designed". Such, at 

 once, put a barrier to all further investigations ; and so does a 

 belief in Natural Selection. 



Bacon saw the utterly unphilosophical character of this 

 deductive method of reasoning : " The handling of final causes, 

 mixed with the rest in physical enquiries, hath intercepted the 

 severe and diligent enquiry of all real and physical causes, and 

 given men the occasion to stay upon these satisfactory and 

 specious causes, to the great arrest and prejudice of further 

 discovery " } 



Natural Selection has had a precisely similar effect. It has 



' De Augment. Sc, ii., 105. 



