Criticisms of Theory of Natural Selection. 377 



other hand, as we have seen in the preceding chapter, 

 there is a vast accumulation of evidence in favour of 

 the theory. Hence, it is no wonder that the theory 

 has now been accepted by all naturahsts, with scarcely 

 any one notable exception, as at any rate the best 

 working hypothesis which has ever been propounded 

 whereby to explain the facts of organic evolution. 

 Moreover, in the opinion of those most competent to 

 judge, the theory is entitled to be regarded as some- 

 thing very much more than a working hypothesis : 

 it is held to be virtually a completed induction, or, 

 in other words, the proved exhibition of a general 

 law, whereby the causation of organic evolution ad- 

 mits of being in large part — if not altogether — 

 explained. 



Now, whether or not we subscribe to this latter 

 conclusion ought, I think, to depend upon v/hat we 

 mean by an explanation in the case which is before 

 us. If we mean only that, given the large class of 

 known facts and unknown causes which are conveni- 

 ently summarized under the terms Heredity and 

 Variability, then the further facts of Struggle and 

 Survival serve, in some considerable degree or 

 another, to account for the phenomena of adaptive 

 evolution, I cannot see any room to question that 

 the evidence is sufficient to prove the statement. 

 But it is clear that by taking for granted these great 

 facts of Heredity and Variability, we have assumed 

 the larger part of the problem as a whole. Or, more 

 correctly, by thus generalizing, in a merely verbal 

 form, all the unknown causes which are concerned in 

 these two great factors of the process in question, we 

 are not so much as attempting to explain the pre- 



