BIOLOGICAL EVOLUTION 77 



natural selection in the struggle between individuals where Dar- 

 win laid chief emphasis. 1 



There seems to be a strong tendency now to accept the theory 

 of mutations in the line of inheritable unit characters, to empha- 

 size the unity of the species in the struggle for existence and to 

 rate highly the importance of geographical isolation in the 

 formation of new species and ethnic groups. There seems to be 

 a tendency in certain quarters, also, following the lead of Nageli 

 and Driesch, to return to the hyper-scientific method of earlier 

 days and posit a life principle or force as the mainspring of 

 development. This is strongly opposed, however, by those who 

 hold that science is weakened just in proportion as it gets beyond 

 the domain of demonstrable facts, so on the whole sociology can 

 claim little support for this theory from biologists of recognized 

 authority. 2 



Most clear and certain of all, it would seem, stands out above 

 the confusion of present biological knowledge and hypotheses the 

 doctrine of adaptation though with differences of interpretation 

 and emphasis. In proportion as the struggle is between individ- 

 uals, either friends or foes, the weak and otherwise less adapted 

 tend to be eliminated, but in proportion as the struggle is between 

 groups certain instincts seem to have been evolved which have as 

 their specific function the strengthening of the group in collective 

 activity. Some of these instincts seem to work for the detriment 

 of the individual member who does not fit in with the " group 

 sentiment of safety " 3 or whose death will in some way be 

 advantageous to the group as in the destruction of the weak, the 



1 For a sane criticism of Darwinism, see Kellogg, Darwinism To-day, chs. Ill, 

 IV, V. 



2 Although this theory is in general repudiated as extra-scientific and tending 

 to turn scientists aside from their supreme task of finding out the efficient causes 

 of change, the vast realm of mystery that still baffles biologists in their endeavor 

 to explain the process of biological evolution and has led some to posit a force or 

 intelligence as the cause of these changes, gives a vantage ground for social phi- 

 losophers who are not limited, as are scientists, to mere description in terms of co- 

 existence and sequence, but have as their task to push their investigations and 

 formulations on to an underlying or final cause as have Ratzenhofer, Fiske, and 

 Ward. Cf. Kellogg, op. cit., pp. 226 f. 



3 Ward, Pure Sociology, pp. 134, 419. 



