CHAPTER HI 

 IS ORGANIC EVOLUTION AN ESTABLISHED PRINCIPLE? 



i. Is there definite proof of organic evolution? 



2. If so, what is the nature of the proof ? 



3. What are the evidences of evolution, and in what ways do these 

 bear witness that evolution has occurred and is still occurring ? 



Before presenting in any detail the several bodies of data that 

 constitute the "evidences of evolution," let us anticipate a little by 

 attempting to answer the three questions just propounded. 



1. Reluctant as he may be to admit it, honesty compels the 

 evolutionist to admit that there is no absolute proof of organic 

 evolution. But, for that matter, there is no absolute proof of any- 

 thing that depends on records of past events. We have no absolute 

 proof that Caesar or Napoleon once lived, or fought, or conquered. 

 All we have are the accounts left by the historians which we accept 

 without question because they are the products of human thought and 

 imagination. There is no absolute proof for either of the more or less 

 directly opposed theories of the origin of the material universe: the 

 "nebular hypothesis" of Laplace, and the " planetesimal hypothesis" 

 of Chamberlin and Moulton. Both of these theories rest upon 

 exactly the same types of evidences as does the theory of organic evolu- 

 tion, viz., the amassing of facts which appear to be explicable on the 

 assumption that the one or the other theory is true. If all of the facts 

 are in accord with it, and none are found that are incapable of being 

 reconciled with it, a working hypothesis is said to have been advanced 

 to the rank of a proved theory. As yet it is impossible to say that 

 either of these theories as to the origin of the universe has been proved. 

 Yet there is much less popular opposition to the acceptance of these 

 theories as facts than there is to the general theory of organic evolu- 

 tion. Similarly, there are certain widely accepted theories of the 

 origin of the present conditions of the earth's crust, and its liquid and 

 gaseous envelopes. The accepted theory, as given us by Hutton and 

 especially by Lyell, is essentially an evolutionary theory and depends 

 for its proof on almost exactly the same types of evidence as does that 



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