AUTONOMY OF THE SCIENCES 223 



of human knowledge. The science of astronomy is governed by 

 mathematical laws ; but what difEerentiates astronomy, what 

 makes it into an autonomous science, is precisely the possession 

 of laws sui generis governing phenomena sui generis. In the 

 same way, mathematical laws are at the basis of the physico- 

 chemical sciences ; but phenomena with which the latter more 

 especially -deal do not come within the domain proper of mathe- 

 matics. Because the more speciahsed sciences cannot be estab- 

 lished independently of the more general laws which govern more 

 generalised phenomena ; because sociology has to take accoimt 

 of the individual unit of society, and has to study the laws to 

 which the psychological development of the individual conforms ; 

 because the psychological activity of the individual, in its turn, 

 is conditioned by the brain structure, which has to be studied 

 as a physiological entity, and in relation to the physiological 

 metaboUsm of the organism ; because physiology merges gradually 

 into organic chemistry, which, in its turn, resolves itself into 

 inorganic chemistry ; because, in the final instance, all pheno- 

 mena, from the most general to the most special, from the most 

 homogeneous to the most complicated, are governed by the 

 imiversal law of gravitation ; are we justified in saying, therefore, 

 that sociology is but individual psychology generaMsed ; that 

 psychology is but a branch of physiology ; that physiology itself 

 is but a complication of physico-chemical phenomena ; and that 

 physico-chemical phenomena are but peculiar conditions of 

 material equilibria which come within the scope of mathe- 

 matical laws ? If we deny the right of sociology to autonomous 

 existence by reducing it to a ' social psychology,' after the 

 manner of Tarde, or the right of psychology to autonomous 

 existence by reducing it to a branch of physiology, we likewise 

 deny the right of every science, apart from mathematics, to 

 autonomous existence ; and we shall be logical in reducing all 

 phenomena, physico - chemical, physiological, psychological, 

 social, to the one universal mathematical law of gravitation. 



