470 LOGIC OF THE MORAL SCIENCES. 



of further differences without any assignahle limit, capable of 

 operating on their industrial prosperity, as well as on every 

 other feature' of their condition, in more ways than can he 

 enumerated or imagined. There is thus a demonstrated 

 impossibility of obtaining, in the investigations of the social 

 science, the conditions required for the most conclusive form 

 of inquiry by specific experience. 



In the absence of the direct, we may next try, as in other 

 cases, the supplementary resource, called in a former place the 

 Indirect Method of Difference : which, instead of two instances 

 differing in nothing but the presence or absence of a given 

 circumstance, compares two classes of instances respectively 

 agreeing in nothing but the presence of a circumstance 

 on the one side and its absence on the other. To choose 

 the most advantageous case conceivable, (a case far too ad- 

 vantageous to be ever obtained,) suppose that we compare 

 one nation which has a restrictive policy, with two or more 

 nations agreeing in nothing but in permitting free trade. We 

 need not now suppose that either of these nations agrees with 

 the first in all its circumstances ; one may agree with it in 

 some of its circumstances, and another in the remainder. 

 And it may be argued, that if these nations remain poorer 

 than the restrictive nation, it cannot be for want either of the 

 first or of the second set of circumstances, but it must be for 

 want of the protective system. If (we might say) the restrictive 

 nation had prospered from the one set of causes, the first 

 of the free-trade nations would have prospered equally; if 

 by reason of the other, the second would : but neither has : 

 therefore the prosperity was owing to the restrictions. This 

 will be allowed to be a very favourable specimen of an argu- 

 ment from specific experience in politics, and if this be 

 inconclusive, it would not be easy to find another preferable 

 to it. 



Yet, that it is inconclusive, scarcely requires to be pointed 

 out. Why must the prosperous nation have prospered from 

 one cause exclusively? National prosperity is always the 

 collective result of a multitude of favourable circumstances ; 

 and of these, the restrictive nation may unite a greater number 



