610 LOGIC OF THE MORAL SCIENCES. 



§ 2. The first difficulty which meets us in the attempt to apply experi- 

 mental methods for ascertaining the laws of social phenomena, is that we 

 are without the means of making artificial experiments. Even if we could 

 contrive experiments at leisure, and try them without limit, we should do 

 so under immense disadvantage ; both from the impossibility of ascei'tain- 

 ing and taking note of all the facts of each case, and because (those facts 

 being in a perpetual state of change), before sufficient time had elapsed to as- 

 certain the result of the experiment, some material circumstances would al- 

 ways have ceased to be the same. But it is unnecessary to consider the log- 

 ical 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 can not adapt our logical means to our wants, by varying the circum- 

 stances as the exigencies of elimination may require. If the spontaneous 

 instances, formed by contemporary events and by the successions of phe- 

 nomena ^'ecorded in history, afford a sufficient variation of circumstances, 

 an induction from specific experience is attainable; otherwise not. The 

 question to be resolved is, therefore, whether the requisites for induction 

 respecting the causes of political effects or the properties of political agents, 

 are to be met with in history ? including under the term, contemporai*y his- 

 tory. 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 po- 

 litical inquiry or controversy ; 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 scientific question 

 to be investigated by specific experience. 



§ 3. In order to apply to the case the most perfect of the methods of ex- 

 perimental inquiry, the Method of Difference, we require to find two in- 

 stances which tally in every particular except the one which is the subject 

 of inquiry. If two nations can be, found which are alike in all natural ad- 

 vantages and disadvantages ; 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 tai-ift", or in other respects interferes 

 more with the freedom 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 expe- 

 rimentum cruets: a real proof by experience, which of the two systems is 

 most favorable to national riches. But the supposition that two such in- 

 stances can be met with is manifestly absurd. Nor is such a concurrence 

 even abstractedly possible. Two nations which agreed in every thing 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-existing causes. If the two nations differ in this 

 portion of their institutions, it is from some difference in their position, 

 and thence in their apparent interests, or in some portion or other of their 

 opinions, habits, and tendencies ; which opens a 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 condition, in more ways 

 than can be enumerated or imagined. There is thus a demonstrated im- 

 possibility of obtaining, in the investigations of the social science, the con- 

 ditions required for the most conclusive form of inquiry by specific experi- 

 ence. 



