330 LOGIC 



that in every case categories should be incapable of reduction to 

 each other. 



A doctrine of categories seems to me to be of the greatest import- 

 ance in the systematization of knowledge, for no problem of relation 

 is even stateable correctly before the type of existence to which its 

 terms belong has been first determined. I submit one illustration 

 to reinforce this general statement, namely, the relation of mind to 

 body. If mind and body belong to the same type of existence, we 

 have one set of problems on our hands; but if they do not, we have 

 an entirely different set. Yet volumes of discussion written on this 

 subject have abounded in confusion, simply because they have 

 regarded mind and body as belonging to radically different types of 

 existence and yet related in terms of the type to which one of them 

 belongs. The doctrine of parallelism is, perhaps, the epitome of this 

 confusion. 



The doctrine of categories will involve not only the greater part 

 of formal and symbolic logic, but will undoubtedly carry the logician 

 into the doctrine of method. Here it is to be hoped that recent 

 tendencies will result in effectively breaking down the artificial dis- 

 tinctions which have prevailed between deduction and induction. 

 Differences in method do not result from differences in points of de- 

 parture, or between the universal and the particular, but from the 

 categories, again, which give the method direction and aim, and 

 result in different types of synthesis. In this direction, the logician 

 may hope for an approximately correct classification of the various 

 departments of knowledge. Such a classification is, perhaps, the 

 ideal of logical theory. 



