474 LOGIC OF THE MORAL SCIENCES. 



supposes that the causes from which part of the effect pro- 

 ceeded are already known ; and as we have shown that these 

 cannot have been known by specific experience, they must 

 have been learnt by deduction from principles of human 

 nature ; experience being called in only as a supplementary 

 resource, to determine the causes which produced an unex- 

 plained residue. But if the principles of human nature may 

 be had recourse to for the establishment of some political 

 truths, they may for all. If it be admissible to say, England 

 must have prospered by reason of the prohibitory system, 

 because after allowing for all the other tendencies which have 

 been operating, there is a portion of prosperity still to be 

 accounted for; it must be admissible to go to the same source 

 for the effect of the prohibitory system, and examine what 

 account the laws of human motives and actions will enable us 

 to give of its tendencies. Nor, in fact, will the experimental 

 argument amount to anything, except in verification of a con- 

 clusion drawn from those general laws. For we may subtract 

 the effect of one, two, three, or four causes, but we shall never 

 succeed in subtracting the effect of all causes except one: 

 while it would be a curious instance of the dangers of too 

 much caution, if, to avoid depending on a priori reasoning 

 concerning the effect of a single cause, we should oblige our- 

 selves to depend on as many separate a priori reasonings as 

 there are causes operating concurrently with that particular 

 cause in some given instance. 



We have now sufficiently characterized the gross mis- 

 conception of the mode of investigation proper to political 

 phenomena, which I have termed the Chemical Method. So 

 lengthened a discussion would not have been necessary, if the 

 claim to decide authoritatively on political doctrines were con- 

 fined to persons who had competently studied any one of the 

 higher departments of physical science. But since the gene- 

 rality of those who reason on political subjects, satisfactorily 

 to themselves and to a more or less numerous body of 

 admirers, know nothing whatever of the methods of physical 

 investigation beyond a few precepts which they continue to 

 parrot after Bacon, being entirely unaware that Bacon's con- 



