AND ON LOGIC IN GENERAL. 



191 



Gauls, writer of his own campaigns. No one knows whether we have or have not specified 

 down to Julius Caesar. Add surviving author, and we are safe enough: add composer for the 

 pianoforte, and we are morally certain we have an empty box. But logic takes no account of 

 the actual effect of differences upon the numerical strength of the species. 



Extension and intension both exist, but extension predominates. We often think of 

 class as aggregate of classes, seldom as compound or common part of classes. We hardly 

 reconcile ourselves to the idea of the common part of two classes as a compound: by habit 

 we slip into the notion of the attribute of the common part as compounded of the attributes of 

 the two. Thus marine is a joint class, both soldier and sailor: but we rather say the marine, 

 the individual, unites both characters. 



2, Physical. This is the most common mode of thought in man's nature, as well as in 

 physics: and my use of the word is not far from that made in the old totum physicum, 

 I mean that this reading is the most common use of the word is : especially in controversy, 

 which is most often about the attributes of things and actions. Man is born and educated a 

 mathematician as to the subject of his propositions, a metaphysician* as to the predicate: he 

 thinks attributively of class in every wrong way and some right ones. His universals are 

 necessities, whether of inclusion or exclusion, not enumerated individual facts. One great use 

 of logic is to teach him the mathematical mode ; that is, to make it more of a habit : one 

 great use of natural history in liberal education is to bring down the metaphysical habit, and 

 raise up the mathematical one, until they are more nearly equipollent. The natural historian 

 predicates of class in class, arranges facts by facts : he savours of the physiologist so soon as 

 his predicate becomes attributive. The logician attempts to point out the human fault and 

 mend it in much the same way as a social reformer would attempt to improve a rude and dirty 

 peasantry, if he should begin by the assurance that they had always lived, and were living, in 

 neat glazed cottages, into which no pig had ever presumed to thrust his snout ; and that all 

 they had to do was to become aware of the fact. He assures the beginner that when he 

 said snow is white, he had not in thought a necessary attribute, for he never had any attri- 

 bute at all : he meant that snows are some white objects, with a distinct reference of possibility 

 to others unnamed. Logic would have been of greater use if it had been distinctly announced 

 that one of its great aims is the abatement of natural philosophy, the increase of the power 



* Contending as much as any one for the distinction be- 

 tween logic and metaphysics, I must yet remind my reader 

 that logic is concerned with the whole form of thought. The 

 necessary form of thought for all practical teaching, is any 

 form which all men actually have, whether we can imagine 

 them to be without it, or not. If every man, saint, savage, or 

 sage, have a certain form of thought, it is the business of logic 

 to teach him to use that form correctly. Now it is a fact that, 

 in their daily thoughts and judgments, all men are metaphy- 

 sicians, and always have been : and the uneducated more than 

 the educated, and children more than grown people. We have 

 all our ideas, which we are constantly applying, about natural 

 and unnatural, necessary and not necessary, e.ssential and not 

 essential, repugnant and not repugnant, cause and effect, de- 

 pendence and independence, possibility and impossibility, &c. 

 &c. &c. These are our strong points. We set out in all our 



inquiries with clear ideas of the naturally possible and impos- 

 sible : we sometimes feel our ignorance as to what is and is not, 

 but never as to what can be and cannot be. Now whether our 

 metaphysics be true or false, it is the business of logic to take 

 care that it be logical. Even if it be the truth that no notions 

 have either essential connexion, or necessary repugnance, it is 

 a law of our minds lo envisage them as having both, and it is 

 a law of our language to tallc of them as having both. But 

 many a man who is metaphysician enough to know that reason 

 is essential to man, is not logician enough to avoid the infer, 

 ence that it is therefore repugnant to the nature of brute. A 

 man may, in his closet, be both an idealist in philosophy and 

 a mathematician in logic : but the moment his toot is on the 

 pavement and his eye on the world, realism and metaphysics 

 resume their sway. 



