156 



REASONING. 



§ 9. The preceding considerations 

 enable us to understand the true 

 nature of what is termed, by recent 

 writers, Formal Logic, and the rela- 

 tion between it and Logic in the 

 widest sense. Logic, as I conceive 



an abuse of language to say, that the proof 

 that Socrates is mortal is that all men are 

 mortal. Turn it in what way we will, this 

 seems to me to be asserting that a thing is 

 the proof of itself. Whoever pronounces 

 the words, All men are mortal, has affirmed 

 that Socrates is mortal, though he may 

 never have heard of Socrates; for since 

 Socrates, whether known to be so or not, 

 really is a man, he is included in the words, 

 All men, and in every assertion of which 

 they are the subject. If the reviewer does 

 not see that there is a difficulty here, I can 

 only advise him to reconsider the subject 

 until he does : after which he will be a 

 better judge of the success or failure of an 

 attempt to remove the difficulty. That be 

 had reflected very little on the point when 

 he wrote his remarks is shown by his over- 

 sight respecting the dictum de omni et nuUo. 

 He acknowledges that this maxim as com- 

 monly expressed, "Whatever is true of a 

 class is true of everything included in the 

 class," is a mere identical proposition, since 

 the class is nothing but the things included 

 in it. But he thinks this defect would 

 be cured by wording the maxim thus, — 

 " Whatever is true of a class is true of 

 everything which can be shown to be a 

 membei- of the class : " as if a thing could 

 '* be shown " to be a member of the class 

 without being one. If a class means the 

 sum of all the things included in the class, 

 the things which can " be shown " to be 

 included in it are part of the sum, and the 

 dictum is as much an identical proposition 

 with respect to them as to the rest. One 

 would almost imagine that in the reviewer's 

 opinion things are not members of a class 

 until they are called up publicly to take 

 their place in it— that so long, in fact, as 

 Socrates is not known to be a man he is not 

 a man, and any assertion which can be 

 made concerning men does not at all re- 

 gard him, nor is affected as to its truth or 

 falsity by anything in which he is con- 

 cerned. 



The difference between the reviewer's 

 theory and mine may be thus stated. Both 

 admit that when we say, All men are 

 mortal, we make an assertion reaching 

 beyond the sphere of our knowledge of 

 individual cases ; and that when a new 

 individual, Socrates, is brought within the 

 field of our knowledge by means of the 

 minor premise, we learn that we have 

 already made an assertion respecting Soc- 

 rates without knowing it : our own gene- 

 ral formula being, to that extent, for the 

 first time interpreted to us. But according 

 to the reviewer's theory, the smaller asser- 



it, is the entire theory of the ascer- 

 tainment of reasoned or inferred truth. 

 Formal Logic, therefore, which Sir 

 William Hamilton from his own point 

 of view, and Archbishop Whately 

 from his, have represented as the 



j tion is proved by the larger : while I con- 

 tend that both assertions are proved to- 

 ] gether by the same evidence, namely, the 

 j grounds of experience on which the gene- 

 I ral assertion was made, and by which it 

 I must be justified. 



I Tiie reviewer says, that if the major pre- 

 I mise included the concluson, "we should 

 be able to affirm the conclusion without the 

 intervention of the minor premise ; but 

 every one sees that that is impossible." 

 A similar argument is urged by Mr. De 

 Morg&n (For 7nal Logic, -p. 259): "The whole 

 objection tacitly assumes the superfluity 

 of the minor; that is, tacitly assumes we 

 know Socrates* to be a man as soon as 

 we know him to be Socrates." The objec- 

 tion would be well grounded if the asser- 

 tion that the major premise includes the 

 conclusion, meant that it individually 

 specifies all it includes. As, however, the 

 only indication it gives is a description by 

 marks, we have still to compare any new 

 individual with the marks; and to show 

 that this comparison has been made is the 

 office of the minor. But since, by suppo- 

 sition, the new individual has the marks, 

 whether we have ascertained him to have 

 them or not ; if we have affirmed the major 

 premise, we have asserted him to be mortal. 

 Now my position is that this assertion can- 

 not be a necessary part of the argument. 

 It cannot be a necessary condition of 

 reasoning that we should begin by making 

 an assertion whicli is afterwards to be em- 

 ployed in proving a part of itself. I can 

 conceive only one way out of this difficulty, 

 viz. that what really forms the proof is the 

 other part of the assertion ; the portion of 

 it, the truth of which has been ascertained 

 previously ; and that the unproved part is 

 bound up in one foimula with the proved 

 part in mere anticipation, and as a memo- 

 randum of the nature of the conclusions 

 which we are prepared to prove. 



With respect to the minor premise in 

 its formal shape, the minor as it stands in 

 the syllogism, predicating of Socrates a 

 definite class name, I readily admit that it 

 is no more a necessary part of reasoning 

 than the major. When there is a major, 

 doing its work by means of a class name, 

 minors are needed to interpret it : but 

 reasoning can be carried on without either 

 the one or the other. They are not the 

 conditions of reasoning, but a precaution 



* Mr. De Morgan says "Plato," but to 

 prevent confusion I have kept to my own 

 exemplum. 



