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THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



trine of Locke, as fully expounded in the fourth 

 book of his great Essay, that knowledge is the 

 perception of the agreement or disagreement of 

 our ideas. 



" Knowledge, then," says Locke, " seems to 

 me to be nothing but the perception of the con- 

 nection and agreement, or disagreement and re- 

 pugnancy, of any of our ideas. In this alone it 

 consists. "Where this perception is, there is knowl- 

 edge ; and, where it is not, there, though we may 

 fancy, guess, or believe, yet we always come short 

 of knowledge." 



Many other philosophers have likewise held 

 that a certain agreement between things, various- 

 ly described as resemblance, similarity, identity, 

 sameness, equality, etc., really constituted the 

 whole of reasoned knowledge as- distinguished from 

 the mere knowledge of sense. Condillac adopted 

 this view, and stated it with admirable breadth 

 and brevity, saying, " L'evidence de raison con- 

 siste uniquement dans l'identite." 



Mill has not failed to discuss this matter, and 

 his opinion on the subject is most expressly and 

 clearly stated in the chapter upon " The Import 

 of Propositions." 1 He analyzes the state of mind 

 called Belief, and shows that it involves one or 

 more of five matters of fact — namely, Existence, 

 Coexistence, Sequence, Causation, Resemblance. 

 One- or other of these is asserted (or denied) in 

 every proposition which is not merely verbal. 

 No doubt relations of the kinds mentioned form 

 a large part of the matter of knowledge, and 

 they must be expressed in propositions in some 

 way or other. I believe that they are expressed 

 in the terms of propositions, while the copula al- 

 ways signifies agreement, or, as Condillac would 

 have said, identity of the terms. But we need 

 not attempt to settle a question of this difficulty. 

 We are only concerned now with the position in 

 his system which Mill assigns to Resemblance. 

 This comes last in the list, and it is with some 

 expression of doubt that Mill assigns it a place 

 at all. He says : 2 



" Besides propositions which assert a sequence 

 or coexistence between two phenomena, there are, 

 therefore, also propositions which assert resem- 

 blance between them— as, this color is like that 

 color; the heat of to-day is equal to the heat of 

 yesterday. It is true that such an assertion might 

 with some plausibility be brought within the de- 

 scription of an affirmation of sequence by consid- 

 ering it as an assertion that the simultaneous con- 

 templation of the two colors is followed by a spe- 



1 Book I., chapter v. 



2 Book I., chapter v.. section 6. 



cific feeling termed the feeling of resemblance. 

 But there would be nothing gained by encumber- 

 ing ourselves, especially in this place, with a gen- 

 eralization which may be looked upon as strained. 

 Logic does not undertake to analyze mental facts 

 into their ultimate elements. Resemblance be- 

 tween two phenomena is more intelligible in it- 

 self than any explanation could make it, and un- 

 der any classification must remain specifically dis- 

 tinct from the ordinary cases of sequence and co- 

 existence." 



It would seem, then, that Mill had, to say the 

 least, contemplated the possibility of resolving 

 Resemblance into something simpler — namely, 

 into a special case of sequence and coexistence ; 

 but he abstains, not apparently because it would 

 be plainly impossible, but because logic does not 

 undertake ultimate analysis. It would encumber 

 us with a " strained generalization," whatever 

 that may be. He therefore accords it provision- 

 ally a place among the matters of fact which 

 logic treats. 



Postponing further consideration of this pas- 

 sage, we turn to a later book of the " System 

 of Logic," in which Mill expresses pretty clearly 

 his opinion that Resemblance is a minor kind of 

 relation to be treated last in the system of Logic, 

 as being of comparatively small importance. In 

 the chapter headed " Of the Remaining Laws of 

 Nature," 1 we find Mill distinctly stating that 2 

 " the propositions which affirm Order in Time, in 

 either of its two modes, Coexistence and Succes- 

 sion, have formed, thus far, the subject of the 

 present book. And we have now concluded the 

 exposition, so far as it falls within the limits as- 

 signed to this work, of the nature of the evidence 

 on which these propositions rest, and the pro- 

 cesses of investigation by which they are ascer- 

 tained and proved. There remain three classes 

 of facts : Existence, Order in Place, and Resem- 

 blance, in regard to which the same questions 

 are now to be resolved." 



From the above passage we should gather 

 that Resemblance has not been the subject treated 

 in the preceding chapters of the third book, or 

 certainly not the chief subject. 



Of the remaining three classes of facts, Exist- 

 ence is dismissed very briefly. So far as relates 

 to simple existence, Mill thinks 3 that the induc- 

 tive logic has no knots to untie, and he proceeds 

 to the remaining two of the great classes into 

 which facts have been divided. His opinion 



1 Book III., chapter xxiv. 



2 First section, near the beginning. 



3 Same section. 



