BOOK V. 



GENEBALIZATION, ANALOGY, AND CLASSIFICATION. 



CHAPTER XXVII. 



GENERALIZATION. 



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 propositions or 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 any thing 

 what we know of similar objects, and it is on this prin- 

 ciple that the whole of deductive reasoning, whether 

 simply logical or mathematico-logical, is founded. All 

 inductive reasoning must therefore be founded on the 

 same principle. Now it might seem that by a very plain 

 use of this principle we might avoid the complicated pro- 

 cesses of induction and deduction, and argue directly from 

 one particular case to another, as the late Mr. J. S. Mill 

 proposed. If the Earth, Venus, Mars, Jupiter, and other 

 planets move in elliptic orbits, cannot we dispense with 

 all elaborate precautions, and assert that Neptune, Ceres, 

 or the last discovered planet must do so likewise 1 ? Do 



