98 NAMES AND PROPOSITIONS. 



ground unless I have the idea of the ground, and of a spade, 

 and of all the other things I am operating upon, and unless I 

 put those ideas together.* But it would be a very ridiculous 

 description of digging the ground to say that it is putting 

 one idea into another. Digging is an operation which is 

 performed upon the things themselves, though it cannot be 

 performed unless I have in my mind the ideas of them. And 

 in like manner, believing is an act which has for its subject 

 the facts themselves, though a previous mental conception 

 of the facts is an indispensable condition. When I say that 

 fire causes heat, do I mean that my idea of fire causes my 

 idea of heat? No: I mean that the natural phenomenon, 

 fire, causes the natural phenomenon, heat. When I mean 

 to assert anything respecting the ideas, I give them their 

 proper name, I call them ideas : as when I say, that a child's 

 idea of a battle is unlike the reality, or that the ideas enter- 

 tained of the Deity have a great effect on the characters of 

 mankind. 



The notion that what is of primary importance to the 

 logician in a proposition, is the relation between the two ideas 

 corresponding to the subject and predicate, (instead of the 

 relation between the two phenomena which they respectively 

 express,) seems to me one of the most fatal errors ever intro- 

 duced into the philosophy of Logic ; and the principal cause 

 why the theory of the science has made such inconsiderable 

 progress during the last two centuries. The treatises on Logic, 

 and on the branches of Mental Philosophy connected with 

 Logic, which have been produced since the intrusion of this 

 cardinal error, though sometimes written by men of extraor- 

 dinary abilities and attainments, almost always tacitly imply a 

 theory that the investigation of truth consists in contemplating 



* Dr. Whewell (Philosophy of Discovery, p. 242) questions this statement, 

 and asks, " Are we to say that a mole cannot dig the ground, except he has an 

 idea of the ground, and of the snout and paws with which he digs it ?" I do 

 not know what passes in a mole's mind, nor what amount of mental apprehen- 

 sion may or may not accompany his instinctive actions. But a human being 

 does not use a spade by instinct ; and he certainly could not use it unless he 

 had knowledge of a spade, and of the earth which he uses it upon. 



