THE CHEMICAL METHOD. 



575 



the same. But it is unnecessary to 

 consider the logical objections which 

 would exist to the conclusiveness of 

 our experiments, since we palpably 

 never have the power of trying any. 

 We can only watch those which nature 

 produces, or which are produced for 

 other reasons. We cannot adapt our 

 logical means to our wants by varying 

 the circumstances as the exigencies of 

 elimination may require. If the spon- 

 taneous instances formed by cotem- 

 porary events and by the successions 

 of phenomena recorded in history 

 afford a sufficient variation of circum- 

 stances, an induction from specific ex- 

 perience is attauiable ; otherwise not. 

 The question to be resolved is, there- 

 fore, whether the requisites for induc- 

 tion respecting the causes of political 

 effects or the properties of political 

 agents are to be met with in history ? 

 including under the term cotempo- 

 rary history. And in order to give 

 fixity to our conceptions, it will be 

 advisable to suppose this question 

 asked in reference to some special 

 subject of political inquiry or contro- 

 versy ; such as that frequent topic of 

 debate in the present century, the 

 operation of restrictive and prohibitory 

 commercial legislation upon national 

 wealth. Let this, then, be the scien- 

 tific question to be investigated by 

 specific experience. 



§ 3. In order to apply to the case 

 the most perfect of the methods of 

 experimental inquiry, the Method of 

 Difference, we require to find two 

 instances which tally in every par- 

 ticular except the one which is the 

 subject of inquiry. If two nations 

 can be found which are alike in all 

 natural advantages and disadvan- 

 tages ; whose people resemble each 

 other in every quality, physical and 

 moral, spontaneous and acquired ; 

 whose habits, usages, opinions, laws 

 and institutions are the same in all 

 respects, except that one of them has 

 a more protective tariff, or in other 

 respects interferes more with the free- 

 dom of industry ; if one of these 



nations is found to be rich and the 

 other poor, or one richer than the 

 other, this will be an experimentum 

 crucis — a real proof by experience 

 which of the two systems is most 

 favourable to national riches. But the 

 supposition that two such instances 

 can be met with is manifestly absurd. • 

 Nor is such a concurrence even 

 abstractedly possible. Two nations 

 which agreed in everything except 

 their commercial policy would agree 

 also in that. Differences of legisla- 

 tion are not inherent and ultimate 

 diversities — are not properties of 

 Kinds. They are effects of pre-exist- 

 ing causes. If the two nations differ 

 in this portion of their institutions, it 

 is from some difference in their posi- 

 tion, and thence in their apparent 

 interests, or in some portion or other 

 of their opinions, habits, and ten- 

 dencies ; which opens a view of fur- 

 ther differences without any assignable 

 limit, capable of operating on their 

 industrial prosperity, as well as on 

 every other feature of their condition, 

 in more ways than can be enumerated 

 or imagined. There is thus a de- 

 monstrated 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 in- 

 stances differing in nothing but the 

 presence or absence of a given circum- 

 stance, compares two classes of in- 

 stances respectively agreeing in no- 

 thing but the presence of a circum- 

 stance 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 ob- 

 tained,) 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 



