4O The Evolution Hypothesis. 



existence of phenomena, in all respects that are essen- 

 tial to the point of view in question, identical with 

 those lying within experience, we are not entitled to 

 assume the applicability of the law beyond the region 

 in which its operation has been observed. No experi- 

 ential law carries with it the authority of a universal 

 truth. 



(2). Every law of nature, being a generalization 

 from experience, is more or less inexact. The degree 

 of inexactness varies from rough approximations to 

 formulae which may be made the basis of calculations 

 that are justified by the foretold event ; yet it will 

 not be claimed for any generalized experience that 

 it is characterized by absolute precision. The laws of 

 number and form dealing with purely abstract re- 

 lations are absolutely true ; but the laws of nature 

 have to do with concrete things not with abstrac- 

 tions. They express the mode of action of complex 

 realities. No experiential law can be established by 

 demonstration. Its truth lies in the exactness with 

 which it interprets the mode of action of classes of 

 concrete existences, and is not in any case absolute. 

 It might, indeed, be questioned if any object whatever 

 has been known to act with perfect precision accord- 

 ing to any known law or combination of known laws. 

 Law, as generalized from observation, is not in any 

 instance obeyed perfectly. Law is abstract: objects 

 are concrete. The formula which expresses a law 

 of nature cannot include the conditions which are 



