CHAPTER XXIII. 



THE USE OF HYPOTHESIS. 



IF the views upheld in this work be correct, all inductive 

 investigation consists in the marriage of hypothesis and 

 experiment. When facts are in our possession, we frame 

 an hypothesis to explain their relations, and by the success 

 of this explanation is the value of the hypothesis to be 

 judged. In the invention and treatment of such hypotheses, 

 we must avail ourselves of the whole body of science 

 already accumulated, and when once we have obtained a 

 probable hypothesis, we must not rest until we have verified 

 it by comparison with new facts. We must endeavour by 

 deductive reasoning to anticipate such phenomena, espe- 

 cially those of a singular and exceptional nature, as would 

 happen if the hypothesis be true. Out of the infinite 

 number of experiments which are possible, theory must 

 lead us to select those critical ones which are suitable for 

 confirming or negativing our anticipations. 



This work of inductive investigation cannot be guided 

 by any system of precise and infallible rules, like those of 

 deductive reasoning. There is, in fact, nothing to which 

 we can apply rules of method, because the laws .of nature 

 must be in our possession before we can treat them. If 

 there were any rule of inductive method, it would direct 

 us to make an exhaustive arrangement of facts in all 

 possible orders. Given the specimens in a museum, we 

 might arrive at the best classification by going systematically 

 through all possible classifications, and, were we endowed 

 with infinite time and patience, this would be an effective 

 method. It is the method by which the first simple steps 



