218 OPERATIONS SUBSIDIARY TO INDUCTION. 



in the most important and the most numerous cases 

 are evolved by abstraction from the very phenomena 

 which it is their office to colligate. I am far from 

 wishing to imply that it is not often a very difficult 

 thing to perform this process of abstraction well, or 

 that the success of an inductive operation does not, in 

 many cases, principally depend upon the skill with which 

 we perform it. Bacon, in his forcible manner, desig- 

 nated as one of the principal obstacles to good induc- 

 tion, general conceptions wrongly formed, " notiones 

 temer a rebus abstractas:" to which Mr. Whewell adds, 

 that not only does bad abstraction make bad induc- 

 tion, but that in order to perform induction well, we 

 must have abstracted well; our general conceptions 

 must be " clear" and " appropriate" to the matter in 

 hand. Nor can it be doubted that, in what they thus 

 said, both Bacon and Mr. Whewell, though they 

 expressed their meaning vaguely, had a meaning, and 

 a highly important one. 



3. In attempting to show what the difficulty in 

 this matter really is, and how it is surmounted, I 

 must beg the reader, once for all, to bear this in mind : 

 That although in discussing Mr. WhewelFs opinions 

 I am willing to adopt his language, and to speak, 

 therefore, of connecting facts through the instrumen- 

 tality of a conception, this technical phraseology 

 means neither more nor less than what is commonly 

 called comparing the facts with one another and 

 determining in what they agree. Nor has the tech- 

 nical expression even the advantage of being meta- 

 physically correct. The facts are not connected; they 

 remain separate facts as they were before. The ideas 

 of the facts may become connected, that is, we may 

 be led to think of them together; but this conse- 



