8 INTRODUCTION. 



analytical cliemlsti-y are not the less valuable, though it should be dis- 

 covered that all which we novs^ call simple substances are really com- 

 pounds. All other things are at any rate compounded of those 

 elements : whether the elements themselves admit of decomposition, 

 is an important inquiry, but does not affect the certainty of the science 

 up to that point. 



I shall, accordingly, attempt to analyze the process of inference, 

 and the processes subordinate to inference, so far only as may be 

 requisite for ascertaining the difference between a correct and an 

 incorrect perfonnance of those processes. The reason for thus hmit- 

 ing our design, is evident. It has been said by objectors to logic, that 

 we do not learn to use our muscles by studying their anatomy. The 

 fact is not quite fairly stated ; for if the action of any of om* muscles 

 were vitiated by local weakness, or other physical defect, a knowledge 

 of their anatomy might be very necessaiy for effecting a cvire. But 

 we should be justly liable to- the criticism involved in this objection, 

 were we, in a treatise on Logic, to carry the analysis 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 fi-om those which ought not. To a similar extent, and 

 no further, it is necessaiy that the logician should analyze the mental 

 processes with which Logic is concerned. Any ulterior and minuter 

 analysis must be left to transcendental metaphysics ; which in this, as 

 in other parts of our mental nature, decides what are ultimate facts, 

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

 found that the conclusions arrived at in this work have no necessary 

 connexion with any particular views respecting the ulterior analysis. 

 Logic is common gi'ound 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 philosophers will no doubt occasion- 

 ally be controverted, since all of them were logicians as well as meta- 

 physicians ; but the field on which their great battles have been fought, 

 lies beyond the boundaries of our science ; and the views which will 

 be here promulgated, may, I believe, be held in conjunction with the 

 principal conclusions of any one of their systems of philosophy. 



It cannot, indeed, be pretended that logical principles can be alto- 

 gether iiTelevant to those more abstruse discussions ; nor is it possible 

 but that the view we are led to take of the problem which logic pro- 

 poses, must have a tendency favorable to the adoption of some one 

 opinion on these controverted subjects rather than another. Logic, 

 although differing from the higher metaphysics like the other half of a 

 great whole (the one being the science of the appreciation of evidence, 

 the other having for its main object to determine what are the propo- 

 sitions for the establishment of which evidence is not required), yet 

 when viewed under another of its aspects, stands in the same relation 

 to this, its sister science, as it does to all the other sciences. For 

 metaphysics, in endeavoring to solve its own peculiar problem, must 

 employ means, the validity ofwhich falls under the cognizance of logic. 

 It proceeds, no doubt, as far as possible, merely by a closer and more 

 attentive interrogation of our consciousness, or, more properly speak- 

 ing, of our memory ; and so far is not amenable to logic. But where- 



