542 LOGIC OF THE MORAL SCIENCES. 



view of further differences without any assignable 

 limit, capable of operating on their industrial pros- 

 perity, as well as on every other feature of their con- 

 dition, in more ways than can be enumerated or ima- 

 gined. 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, com- 

 pares 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 

 advantageous 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 circum- 

 stances, but it must be for want of the protecting 

 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 re- 

 strictions. This will be allowed to be a very favour- 

 able specimen of an argument from specific experience 



