160 THE FALLACIES OF NATURAL SELECTION. 



such development within a year, these ducks may, 

 within a million of years, develop into higher species 

 and genera ; and a perfect analogue will be had, of the 

 argument from increase of structure following increased 

 activity. The webbed feet are but the re-development, 

 of what was once lost, by the species in question; and 

 any argument, founded thereupon, designed to prove 

 the possibility of indefinitely continued development, 

 is manifestly a gross petitio principii. 



Third: As we have seen, Darwin argues, that there 

 must be slight advances in development, because, in 

 each generation, Natural Selection picks out "the 

 stronger and more vigorous" to continue the line of 

 descent. Whatever semblance of strength is in this 

 argument, we have shown to be due to the most 

 transparent of fallacies. Conscious, probably, of the 

 absurdity of such an argument, Darwin deemed it 

 necessary to supplement this mode of getting the 

 slight development, for Natural Selection to accumu- 

 late, with a gratuitous assumption. 



He assumes, that there are pronounced variations 

 which arise, under nature, seemingly in the same inex- 

 plicable and spontaneous manner in which he deems 

 the improvements, under domestication, to present 

 themselves. This is his assumption. His argument 

 therefrom, runs to the effect; that, most probably the 

 possession of such a variation gives to the individual 

 possessing it, such an advantage in the struggle for 

 existence, as to ensure its survival, and the transmis- 

 sion of such variation to its descendants; that such 

 descendants, " in the course of thousands of genera- 



