504 INDUCTION. 



comparing the state of things following .the experiment with 

 the state which preceded it, is thus, in the case of intermixture 

 of effects, entirely unavailing ; because other causes than that 

 whose effect we are seeking to determine, have been operating 

 during the transition. As for the other mode of employing 

 the Method of Difference, namely by comparing, not the same 

 case at two different periods, but different cases, this in the 

 present instance is quite chimerical. In phenomena so com- 

 plicated it is questionable if two cases, similar in all respects 

 but one, ever occurred ; and were they to occur, we could not 

 possibly know that they were so exactly similar. 



Anything like a scientific use of the method of experiment, 

 in these complicated cases, is therefore out of the question. 

 We can in the most favourable cases only discover, by a suc- 

 cession of trials, that a certain cause is very often followed by 

 a certain effect. For, in one of these conjunct effects, the 

 portion which is determined by any one of the influencing 

 agents, is generally, as we before remarked, but small ; and it 

 must be a more potent cause than most, if even the tendency 

 which it really exerts is not thwarted by other tendencies in 

 nearly as many cases as it is fulfilled. 



If so little can be done by the experimental method to 

 determine the conditions of an effect of many combined causes, 

 in the case of medical science ; still less is this method appli- 

 cable to a class of phenomena more complicated than even 

 those of physiology, the phenomena of politics and history. 

 There, Plurality of Causes exists in almost boundless excess, 

 and effects are, for the most part, inextricably interwoven 

 with one another. To add to the embarrassment, most of the 

 inquiries in political science relate to the production of effects 

 of a most comprehensive description, such as the public wealth, 

 public security, public morality, and the like : results liable to 

 be affected directly or indirectly either in plus or in minus by 

 nearly every fact which exists, or event which occurs, in human 

 society. The vulgar notion, that the safe methods on political 

 subjects are those of Baconian induction that the true guide 

 is not general reasoning, but specific experience will one day 

 be quoted as among the most unequivocal marks of a low state 



