viii CONCEPTUAL RECONSTRUCTION 13-5 



deductive reasoning is often illusory because the generalis- 

 ations on which it rests are not strictly proven, and the 

 new combination may be precisely the modification in 

 which they will not hold good. All intellectual construc- 

 tion is therefore at bottom of hypothetical character, and 

 requires reference to experience to establish its premisses 

 and test its conclusions. 



3. Thus we can deal fruitfully with concepts, combining 

 and analysing them without reference back to experience, 

 provided always that the result of each operation depends on 

 the elements entering into it and on nothing else, and pro- 

 vided further that the elements entering into combination 

 have no effect on each other apart from that contemplated 

 in the combination. Fallacies arise when ignoring this 

 condition we attribute to physical things combined effects 

 corresponding to our constructions without specific evi- 

 dence of this correspondence. Fallacies arise also when 

 the concept is modified unawares as it passes from one 

 usage or combination to another. This happens the more 

 easily because in most reasoning the concept is represented 

 by a word which always will have many associations in 

 virtue of which its meaning is elastic and tends to bulge 

 on this side or that in accordance with the pressure or 

 tension of the context. The concept may thus come to 

 diverge materially from the experience out of which it was 

 educed, and so yield false combinations or engender unreal 

 difficulties. In particular, in the mere fact that it separates 

 from experience and sets up as an object of contempktion 

 on its own account, the concept undergoes changes of 

 character which are a fruitful source of fallacy. 



Fallacies of this order, arising ultimately from a mis- 

 interpretation of the relation of the concept to experience, 

 underlie much metaphysical speculation ancient and modern. 

 They are the source on the one side of Mysticism and on 

 the other of Materialism. They form the make up of the 

 legalistic and formalistic type of mind. It is therefore well 

 to examine them with some care and to illustrate them 

 with some detail, and in doing so we can draw all that we 

 need from contemporary thought. For though as I shall 



