ORGANIC EVOLUTION. Si 



certainly not demonstrated as a matter of scien- 

 tific fact. But when a theory has been raised to 

 such a level of probability as this, it is, for all 

 practical purposes, as good as a demonstration. 

 Thus, in the particular instance before us, even 

 if the sceptical demand for evidence, which from 

 the nature of the case is clearly impossible, were 

 granted, and if we could actually observe the 

 transmutation of species, the fact would not 

 exert any further influence on the progress of 

 science than is now exerted by the large and 

 converging bodies of evidence which leave no 

 other rational theory open to us than that such 

 transmutation has taken place. Therefore, it 

 seems to me, the hypercritical objection which 

 we are considering is really founded on a mis- 

 conception of scientific method, and of what it 

 is that justifies a scientific doctrine. Assuredly, 

 in the case of every theory, as distinguished 

 from a demonstration, there must always be a 



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