SCIENTIFIC METHOD IN PHILOSOPHY 103 



namely, that, although almost everything in science is 

 found sooner or later to require some correction, yet this 

 correction is almost always such as to leave untouched, or 

 only slightly modified, the greater part of the results 

 which have been deduced from the premiss subsequently 

 discovered to be faulty. The prudent man of science 

 acquires a certain instinct as to the kind of uses which 

 may be made of present scientific beliefs without incurring 

 the danger of complete and utter refutation from the 

 modifications likely to be introduced by subsequent 

 discoveries. Unfortunately the use of scientific generalisa- 

 tions of a sweeping kind as the basis of philosophy is 

 just that kind of use which an instinct of scientific caution 

 would avoid, since, as a rule, it would only lead to true 

 results if the generalisation upon which it is based stood 

 in no need of correction. 



We may illustrate these general considerations by 

 means of two examples, namely, the conservation of 

 energy and the principle of evolution. 



(i) Let us begin with the conservation of energy, or, 

 as Herbert Spencer used to call it, the persistence of 

 force. He says :^ 



" Before taking a first step in the rational inter- 

 pretation of Evolution, it is needful to recognise, 

 not only the facts that Matter is indestructible and 

 Motion continuous, but also the fact that Force 

 persists. An attempt to assign the causes of Evo- 

 lution would manifestly be absurd if that agency to 

 which the metamorphosis in general and in detail 

 is due, could either come into existence or cease to 

 exist. The succession of phenomena would in such 

 case be altogether arbitrary, and deductive Science 

 impossible." 



* First Princtples (1^62), Part II, beginning of chap. viii. 



