430 The Inward Urge to Change 



of a species; but it has also led to excessive specialization to 

 the point of handicapping individuals and species. We have 

 no satisfactory theory to explain orthogenetic variation, ex- 

 cept the assumption of an " inherent tendency," of some- 

 thing in the nature of living matter. This assumption need 

 not be in the form of a mystic dismissal of a scientific prob- 

 lem: it may be an objective, although tentative, description 

 of living matter as having, among others, the property or 

 tendency of developing along such and such lines. 



The attempt to explain what happens in the living 

 world runs into the existence of many orders or levels of 

 reality, so related to one another that, while happenings in 

 one level are contingent upon events in another, we have no 

 way of knowing just what the connection is. We can work 

 out satisfactory laws of causo-mechanic relationship within 

 a given order, but cannot transfer these laws to a different 

 order. The idea of emergence helps to bridge these gaps, at 

 least formally. It helps us to search for causo-mechanical 

 principles in living beings without waiting to build up a 

 complete system of knowledge covering the entire universe, 

 from the electron to the soul of man in society. It helps us 

 to accept the appearance of new qualities, new kinds of 

 phenomena, without resorting to miracles and magic. It 

 helps us to conceive of evolution as an orderly process with- 

 out insisting upon absolute continuity or upon " missing 

 links." A better understanding of the actual workings of 

 living bodies makes possible our reliance upon general laws or 

 uniformity and at the same time our recognition of constant 

 change as inherent in life. 



