504 LOGIC OF THE MORAL SCIENCES. 



fying the general sufficiency of the theory. The test of the 

 degree in which the science affords safe ground for predicting 

 (and consequently for practically dealing with) what has not 

 yet happened, is the degree in which it would have enabled us 

 to predict what has actually occurred. Before our theory of 

 the influence of a particular cause, in a given state of circum- 

 stances, can be entirely trusted, we must be able to explain and 

 account for the existing state of all that portion of the social 

 phenomena which that cause has a tendency to influence. If, 

 for instance, we would apply our speculations in political 

 economy to the prediction or guidance of the phenomena of 

 any country, we must be able to explain all the mercantile or 

 industrial facts of a general character, appertaining to the 

 present state of that country : to point out causes sufficient to 

 account for all of them, and prove, or show good ground for 

 supposing, that these causes have really existed. If we cannot 

 do this, it is a proof either that the facts which ought to be 

 taken into account are not yet completely known to us, or 

 that although we know the facts, we are not masters of a suffi- 

 ciently perfect theory to enable us to assign their consequences. 

 In either case we are not, in the present state of our know- 

 ledge, fully competent to draw conclusions, speculative or 

 practical, for that country. In like manner if we would 

 attempt to judge of the effect which any political institution 

 would have, supposing that it could be introduced into any 

 given country ; we must be able to show that the existing 

 state of the practical government of that country, and of what- 

 ever else depends thereon, together with the particular character 

 and tendencies of the people, and their state in respect to the 

 various elements of social well-being, are such as the institu- 

 tions they have lived under, in conjunction with the other cir- 

 cumstances of their nature or of their position, were calculated 

 to produce. 



To prove (in short) that our science, and our knowledge of 

 the particular case, render us competent to predict the future, 

 we must show that they would have enabled us to predict the 

 present and the past. If there be anything which we could 



