ASPECTS OF KINETIC EVOLUTION 227 



Science deals primarily with facts, and only incidentally with 

 inferences or theories, though the latter are of immense use in 

 helping to ascertain facts and test their causal relations. Useful 

 theories arrange facts in what appear to be connected sequences, 

 and enable us to project ourselves into the realm of the un- 

 known without hopelessly losing our way in the maze of unre- 

 lated data which we are otherwise likely to encounter. We 

 follow the theory until we encounter facts which prove or dis- 

 prove it, or until a more direct or more coherent theory has 

 been suggested. 



Theories are like legislative enactments; the surest way to be 

 rid of a bad one is to enforce it. A false theory, if studied with 

 sufficient care will correct itself, because the places will be found 

 where it is inapplicable. Moreover, the theories and laws which 

 are the most difficult to repeal are those which contain a large 

 measure of truth and justice, and which have been long in force, 

 so that many vested interests have grown up around them. 

 They take possession, as it were, of the field of investigation, 

 divide it up and place on guard a multitude of technical terms 

 and distinctions which defend the approaches of the citadel of 

 error by a battery of words, which go far to keep a new idea 

 unintelligible. 



The prevalent doctrine that evolution is caused or actuated by 

 natural selection is such a theory, containing a large and impor- 

 tant truth, and at first immensely fertile in scientific results and 

 practical applications, but essentially erroneous, and in some 

 fundamental respects dangerous to agriculture and to man 

 himself. 



The basal axioms, the things taken for granted in the selec- 

 tion theory are (i) that species are normally stationary and con- 

 stant in their characters and (2) that their evolutionary progress 

 is caused by the environment, but neither of these assumptions 

 proves to accord with the facts. It has not been shown that 

 either environment itself or the selection which it exerts are 

 true, efficient causes of evolution. Neither has evidence been 

 found to prove that a species has ever remained stationary in all 

 its characters, or that the component individuals tend to become 

 "exactly alike," even under the most uniform conditions. 



