EVOLUTION 39 



for scientific discussion — but in their comprehension of 

 what the theory really meant and in their failure to realize 

 that a theory with so much prima facie probability might 

 in accordance with all scientific precedent be used deduc- 

 tively to test its validity.! 



It is clear that the Spencerian treatment was wanted 

 as a co-factor with the Darwinian treatment. His work 

 was in our hands just at the right time, and there is no 

 doubt whatever that large numbers of science students 

 were enormously stimulated thereby. The two prime 

 methods of induction and deduction were for us per- 

 sonified by the two great founders of the doctrine of 

 Evolution. 



In pointing out that the more liberal use of the deduc- 

 tive method in the biological sciences was urgently 

 needed at that period it must be imderstood that from 

 the scientific point of view the scientific use of the method 

 only comes under consideration. To accept a deduction 

 as a scientific truth without verification is unscientific, 

 and it must be confessed that both Darwinians and 

 Spencerians have been too apt to accept ' what might be ' 

 or ' what ought to be ' for ' what is '. But from the 

 philosophical point of view a deduction takes another 

 aspect. Granting that such or such a principle arrived 

 at inductively is true, then such or such results should 

 follow. That is the deduction for both Philosophy and 

 Science. Now it is the business of Philosophy in the 

 Spencerian sense, if it is in possession of the broadest 

 of generalizations, to formulate these deductive con- 

 clusions — to tell us for guidance * what might be ' or 

 ' what ought to 'be '. If that be disallowed, then there 

 seems to be no scope for Philosophy as an instrument 

 either of scientific progress or of human culture. If the 

 deductive conclusions are accepted off-hand as demon- 

 strated truths, so much the worse for Science ; if they are 



» See, for instance, Darwin's letter to D. T. Ansted in i860, published 

 in my address to the Entomological Society of 1-ondon in 1897 ; More 

 Letters, vol. ii, p. 175. 



