^: 



324 INDUCTION. 



not invariably followed by success ; but they succeed in so large a propor- 

 tion of cases, and against such powei'ful obstacles, that their tendency to 

 restore health in the disorders for which they are prescribed may be re- 

 garded as an experimental truth,* 



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 applicable 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 si^e- 

 cific experience — will one day be quoted as among the most unequivocal 

 marks of a low state of the speculative faculties in any age in which it is 

 accredited. Nothing can be more ludicrous than the sort of parodies on 

 experimental reasoning which one is accustomed to meet with, not in pop- 

 ular discussion only, but in grave treatises, when the affairs of nations 

 are the theme. " How," it is asked, " can an institution be bad, when the 

 country has prospered under it?" "How can such or such causes have 

 contributed to the prosperity of one country, when another has prospered 

 without them?" Whoever makes use of an argument of this kind, not in- 

 tending to deceive, should be sent back to learn the elements of some one 

 of the more easy physical sciences. Such reasoners ignore the fact of 

 Plurality of Causes in the very case which affords the most signal example 

 of it. So little could be concluded, in such a case, from any possible colla- 

 tion of individual instances, that even the impossibility, in social phenomena, 

 of making artificial experiments, a circumstance otherwise so prejudicial to 

 directly inductive inquiry, hardly affords, in this case, additional reason of 

 regret. For even if we could try experiments upon a nation or upon the 

 human race, with as little scruple as M. Magendie tried them on dogs and 

 rabbits, we should never succeed in making two instances identical in every 

 respect except the presence or absence of some one definite circumstance. 

 The nearest approach to an experiment in the philosophical sense, which 

 takes place in politics, is the introduction of a new operative element into 

 national affairs by some special and assignable measure of government, 

 such as the enactment or repeal of a particular law. But whei*e there are 

 so many influences at work, it requires some time for the influence of any 

 new cause upon national phenomena to become apparent ; and as the causes 

 operating in so extensive a sphere are not only infinitely numerous, but in 

 a state of perpetual alteration, it is always certain that before the effect of 



* What is said in the text on the applicability of the experimental methods to resolve par- 

 ticular questions of medical treatment, does not detract from their efficacy in ascertaining the 

 general laws of the animal or human system. The functions, for example, of the different 

 classes of nerves have been discovered, and probably could only have been discovered, by ex- 

 \ periments on living animals. Observation and experiment are the ultimate basis of all knowl- 

 L edge : from them we obtain the elementary laws of life, as we obtain all other elementary truths. 

 It is in dealing with the complex combinations that the experimental methods are for the most 

 part illusory, and the deductive mode of investigation must be invoked to disentangle the com- 

 plexity. 



