FACT OF EVOLUTION TO THE PHILOSOPHY OF EVOLUTIONISM 353 



Are There Laws of Evolution? 



If we can model our discussion of natural laws upon the 

 methods of physics, the science which has for several centuries 

 set the pace for methodological procedure, three closely inter- 

 related tasks must be performed in establishing a body of 

 knowledge (1) isolate the phenomena to be studied; (2) de- 

 scribe unambiguously what is happening; and (3) discern some 

 specific permanence in the flux of events under observation. 

 By this process, for example, the laws of conservation were 

 formulated/* 



We have seen how equivocity enters into the very texture of 

 evolutionary theory at every level of the " fact." Consequently, 

 in this difficult question of prehistory and origins, there is a 

 special and sometimes insurmountable difficulty in knowing 

 whether the first two conditions above are satisfied. Isolating 

 facts of prehistory and describing them unambiguously is, by 

 the very nature of the problem, a large order. Assuming the 

 most complete and reliable analyses of phylogenies, however, 

 can we discern some specific permanence in the flux of events 

 under observation.'^ 



B. Rensch takes up the problem of the " laws of evolution " 

 in his paper for the Centennial Convention, and the question of 

 the direction of evolution was fully discussed.^'' At first sight, 

 it seems that in the flow of evolutionary events many laws can 

 be formulated: (1) the law of increasing complexity; (2) the 

 law of progressive speciation of phyletic branches; (3) the law 

 of increasing size; (4) the law of migrations; (5) the law of 

 adaptive radiation; (6) the law of irreversibility (Dollo's law) ; 

 (7) the law of evolutionary continuity, etc.''° Rensch lists sixty 

 different rules which seem to have the quality of regularity, 

 and he admits that they can be multiplied indefinitely.*^^ But 



** G. Holton, Introduction to Concepts and Theories in Physical Science (Cam- 

 bridge, 1952) p. 278. ^, 



68 >< 



60 



61 



" The Laws of Evolution," BAD, I, 95-116. /< \C»M /^ 



R. Collin, Evolution (New York, 1959) p. 55. -^^'^^^''''''Tr*^*^ 



EAD,T,UO. /oYo^* 



