24 INTRODUCTION. 



sary for effecting a cure. But we should be justly liable to the criticism' 

 involved in this objection, were we, in a treatise on logic, to carry the anal- 

 ysis of the reasoning process beyond the point at which any inaccuracy 

 which may have crept into it must become visible. In learning bodily 

 exercises (to carry on the same illustration) we do, and must, analyze the 

 bodily motions so far as is necessary for distinguishing those which ought 

 to be performed from those which ought not. To a similar extent, and no 

 further, it is necessary that the logician should analyze the mental processes 

 with which Logic is concerned. Logic has no interest in carrying the anal- 

 ysis beyond the point at which it becomes apparent whether the operations 

 have in any individual case been rightly or wrongly performed: in the 

 same manner as the science of music teaches us to discriminate between 

 musical notes, and to know the combinations of which they are susceptible, 

 but not what number of vibrations in a second correspond to each ; which, 

 though useful to be known, is useful for totally different purposes. The 

 extension of Logic as a Science is determined by its necessities as an Art : 

 whatever it does not need for its practical ends, it leaves to the larger 

 science which may be said to correspond, not to any particular art, but to 

 art in general ; the science which deals with the constitution of the human 

 faculties ; and to which, in the part of our mental nature which concerns 

 Logic, as well as in all other parts, it belongs to decide what are ultimate 

 facts, and what are resolvable into other facts. And I believe it will be 

 found that most of the conclusions arrived at in this work have no neces- 

 sary connection M'ith any particular views respecting the ulterior analysis. 

 Logic is common ground on which the partisans of Hartley and of Reid, 

 of Locke and of Kant, may meet and join hands. Particular and detached 

 opinions of all these thinkers will no doubt occasionally be controverted, 

 since all of them were logicians as well as metaphysicians; but the field on 

 which their principal battles have been fought, lies beyond the boundaries 

 of our science. 



It can not, indeed, be pretended that logical principles can be altogether 

 irrelevant to those more abstruse discussions ; nor is it possible but that 

 the view we are led to take of the problem which logic proposes, must 

 have a tendency favorable to the adoption of some one opinion, on tliese 

 controverted subjects, rather than another. For metaphysics, in endeavor- 

 ing to solve its own peculiar problem, must employ means, the validity of 

 which falls under the cognizance of logic. It proceeds, no doubt, as far as 

 possible, merely by a closer and more attentive interrogation of our con- 

 sciousness, or more properly speaking, of our memory; and so far is not 

 amenable to logic. But wherever this method is insufficient to attain the 

 end of its inquiries, it must proceed, Hke other sciences, by means of evi- 

 dence. Now, the moment this science begins to draw infei'ences from evi- 

 dence, logic becomes the sovereign judge whether its inferences are well 

 grounded, or what other inferences would be so. 



This, however, constitutes no nearer or other relation between logic and 

 metaphysics, than that which exists between logic and every other science. 

 And I can conscientiously affirm that no one proposition laid down in this 

 work lias been adopted for the sake of establishing, or with any reference 

 to its fitness for being employed in establishing, preconceived opinions in 

 any (lei)artmciit of knowledge or of inquiry on which the speculative world 

 is still undecided.* 



* The view tnken in the text, of tiie definition and pnrpose of Logic, stands in mnrked op- 

 position to thiit of tlie school of pliilosophy which, in this country, is represented by the writ- 



