XXXIV INTRODUCTION. 



govern our assent when rightly yielded, know also that 

 all degrees of doubt may and do attach to hypotheses, 

 even in the minds of their originators themselves. 



So stands it with the Darwinian hypothesis when 

 looked at from the scientific point of view. A degree of 

 doubt still hangs over it, as to the amount of which and 

 the co-relative amount of evidence in its favour we must 

 defer to the opinion of the best biologists, supposing them 

 logical and free from mental bias. But it is otherwise 

 when the scientific hypothesis is converted by biologists 

 like Haeckel into a universal philosophical theory a 

 change which, though great and significant in its con- 

 sequences, is easily and often made without notice being 

 taken of it. When the scientific hypothesis of Darwin is 

 turned into a philosophical system called Darwinism, or 

 is made the leading principle in the allied though more 

 complete system of Herbert Spencer, called the Evolu- 

 tion Philosophy ; when it is regarded not merely as a 

 probable scientific hypothesis, but as a full philosophical 

 interpretation of the universe and of the whole course of 

 organic evolution, to say nothing of mental, moral, and 

 social evolution in man ; then it is quite another matter, 

 and we have a right to object to the all-embracing pre- 

 tensions of the hypothesis, even though we be neither 

 specialists nor advanced students in biology. 



In fact, when Natural Selection a name barely 

 serving to mask the infinite play of Chance, which is its 

 essential feature is offered us as the chief or sole creative 

 agency ; when the only principle employed by Nature in 

 the elaboration of the marvels of organic and of all other 

 evolution is said to have been the principle of utility ; 

 when the unfolding of the purpose of the universe is re- 

 solved into movement in " the line of least resistance ; " 

 in a word, when Chance and physical necessity, to the 



