140 INDUCTION. 



generalizations is not very great; for, though it fre- 

 quently happens that we see no reason why that 

 which is true of most individuals of a class is not true 

 of the remainder, nor are able to bring the former under 

 any general description which can distinguish them 

 from the latter, yet if we are willing to be satisfied 

 with propositions of a less degree of generality, and to 

 break down the class A into sub-classes, we may 

 generally obtain a collection of propositions exactly 

 true. We do not know why most wood is lighter 

 than water, nor can we point out any general property 

 which discriminates wood that is lighter than water 

 from that which is heavier. But we know exactly 

 what species are the one and what the other. And if 

 we meet with a specimen not conformable to any 

 known species (the only case in which our previous 

 knowledge affords no other guidance than the approx- 

 imate generalization), we can generally make a specific 

 experiment, which is always a safer resource. 



It oftener happens, however, that the proposition, 

 Most A are B, is not the ultimatum of our scientific 

 progress, though the knowledge we possess beyond it 

 cannot conveniently be brought to bear upon the 

 particular instance. In such a case, we know well 

 enough what circumstances really distinguish the 

 portion of A which have the attribute B from the 

 portion which have it not, but have no means, or no 

 time, to examine whether those characteristic circum- 

 stances exist or not in the individual case. This is 

 generally the situation we are in when the inquiry is 

 of the kind called moral, that is, of the kind which 

 have in view to predict human actions. To enable us 

 to affirm anything universally concerning the actions 

 of classes of men, the classification must be grounded 

 upon the circumstances of their mental culture and 



