ORGANIC EVOLUTION. 



is sufficient to explain the observed phenomena, 

 and all our science and all our philosophy are 

 scattered to the winds. For the law of logic 

 which Sir William Hamilton called the law of 

 parsimony — or the law which forbids us to 

 assume the operation of higher causes when 

 lower ones are found sufficient to explain the 

 observed effects — this law constitutes the only 

 logical barrier between science and superstition. 

 For it is manifest that it is always possible to 

 give a hypothetical explanation of any pheno- 

 menon whatever, by referring it immediately to 

 the intelligence of some supernatural agent; so 

 that the only difference between the logic of 

 science and the logic of superstition consists in 

 science recognising a validity in the law of 

 parsimony which superstition disregards. There- 

 fore I have no hesitation in saying that this way 

 of looking at the evidence in favour of natural 

 selection is not a scientific or a reasonable way 



