INTRODUCTION xxiii 



selection is an indispensable condition of life. The very idea of 

 Evolution implies progress, though whither that progress ulti- 

 mately tends we caimot say ; and progress is impossible unless 

 selection permit exclusively of the survival of the fittest, conse- 

 quently of those who alone are capable of accomphshing any 

 progress. 



Even as the social sphere differentiates itself by phenomena 

 sui generis from the biological and physico-chemical spheres, 

 so does selection operate within it in a distinct manner. Selection 

 utilises the forces which social life has developed, in order to 

 convert them into iastruments for ensuring the progress of 

 society and for eUminating those elements which impede pro- 

 gress. Among the other species the test of fitness is a purely 

 physical one ; among the inferior types of the human species, 

 also, physical superiority is alone sufficient. But as social 

 evolution slowly develops types of greater complexity of struc- 

 ture, and engenders forces which are absent from among other 

 living types, these forces assume a role of ever greater importance 

 in the determining of the fitness or adaptive capacity of a society. 

 Not that physical qualities come to lose any of their importance ; 

 on the contrary, physical qualities play as decisive a role in the 

 evolution of the higher forms of human society as in the evolu- 

 tion of every other form of life. But with the development of social 

 life there is added another criterion of fitness as important as the 

 physical criterion. It is not sufficient for a society to be com- 

 posed of physically fit individuals ; it must possess, also, certain 

 qualities of cohesion and integration which are likewise indis- 

 pensable to it in the struggle for existence with other societies. 

 For without this cohesion and this integration, a society will be 

 torn asunder by the conflicting interests of the different elements 

 which compose it. But a society can endure only on condition 

 that it have an aim, a common purpose, a common ideal, towards 

 the realisation of which all the efforts of all its component indi- 

 viduals must be directed. Hence the cardinal importance of a 



