BOOK V. 



GENERALISATION, ANALOGY, AND 

 CLASSIFICATION. 



CHAPTER XXVII. 



GENERALISATION. 



I HAVE endeavoured to show in preceding chapters that 

 all inductive reasoning is an inverse application of de- 

 ductive reasoning, and consists in demonstrating that the 

 consequences of certain assumed laws agree with facts of 

 nature gathered by active or passive observation. The 

 fundamental process of reasoning, as stated in the outset, 

 consists in inferring of a thing what we know of similar 

 objects, and it is on this principle that the whole of deduc- 

 tive reasoning, whether simply logical or mathematico- 

 logical, is founded. All inductive reasoning must be 

 founded on the same principle. It might seem that by a 

 plain use of this, principle we could avoid the complicated 

 processes of induction and deduction, and argue directly 

 from one particular case to another, as Mill proposed. If 

 the Earth, Venus, Mars, Jupiter, and other planets move 

 in elliptic orbits, cannot we dispense with elaborate pre- 

 cautions, and assert that Neptune, Ceres, and the last 

 discovered planet must do so likewise ? Do we not know 

 that Mr. Gladstone must; die, because he is like other 



