Introduction 



the gulf between the two main divisions of 

 evolutionists is as wide to-day as it was when 

 Butler wrote. It will be well, perhaps, for 

 the benefit of readers who have not followed 

 the history of the theory of evolution during 

 its later developments, to state in a few words 

 what these two main divisions are. All evolu- 

 tionists agree that the differences between 

 species are caused by the accumulation and 

 transmission of variations, but they do not 

 agree as to the causes to which the varia- 

 tions are due. The view held by the older 

 evolutionists, Buffon, Erasmus Darwin and 

 Lamarck, who have been followed by many 

 modern thinkers, including Herbert Spencer 

 and Butler, is that the variations occur mainly 

 as the result of effort and design ; the oppo- 

 site view, which is that advocated by Mr. 

 Wallace in "Darwinism," is that the varia- 

 tions occur merely as the result of chance. 

 The former is sometimes called the teleo- 

 logical view, because it recognises the presence 

 in organic nature of design, whether it be 

 called creative power, directive force, direc- 

 tivity, or vital principle; the latter view, in 



