412 The Inward Urge to Change 



The attempt to apply mechanistic thinking to hfe and evolu- 

 tion, however, is constantly running into such difficulties. 

 On the one hand, evolution as a historical process has meant 

 continuity, gradual change, uninterrupted sequence of cause 

 and effect. On the other hand, the accumulated facts and 

 the new theories now require us to contemplate discon- 

 tinuity. Is not this a substitution of miracle for law? 



It has taken long ages to liberate a comparatively small 

 part of the human race from reliance upon miracles, both 

 as a means of understanding and as a means of practical 

 control of affairs. The cultivation of the concept of " law '* 

 has meant substantial progress in thinking and in elevating 

 the spirit as well as in yielding concrete values through tech- 

 nology and industry. It is possible, however, that this has 

 imposed upon us a new dogma that in its turn obstructs 

 further growth. 



We find again and again that our mechanistic explana- 

 tions will not explain satisfactorily the more complex phe- 

 nomena of life and mind. We are tempted therefore either 

 to give up the effort as futile, and to fall back upon magic 

 and miracles, or to invent categories of forces and agencies 

 that do not let themselves be treated " mechanistically." 

 Yet the only demand which principles of scientific method 

 make upon us is that of uniform causation. 



It is not necessary that we shall be able to explain a 

 mutation in terms of elementary chemistry; or that we shall 

 explain mental processes in terms of levers and valves. It 

 is necessary only that whatever uniformities we discover in 

 any order of events shall be truly universal for that order. 

 For example, a push against an object and the consequent 

 movement represent an event which we can explain in cause- 

 and-effect terms. A push by one man's foot against an- 

 other's toe and the subsequent movements, which may be 

 very intricate indeed, also present an event which we can 

 explain in cause-and-effect terms. Yet nobody supposes 

 that the mechanism of push-and-movement is the same as 

 the mechanism of stimulus-and-response, however simple 



