318 LOGIC 



a mental fact and what riot, with a prevailing tendency to draw the 

 remarkable conclusion that all facts are somehow mental or experi- 

 enced facts. The situation would be worse for psychology than it is, 

 if that vigorous science had not learned from other sciences the valu- 

 able knack of isolating concrete problems and attacking them 

 directly, without the burden of previous logical or metaphysical 

 speculation. Thus knowledge, which is the peculiar province of logic, 

 is increased, while we wait for the acceptable definition of a mental 

 fact. But definitions, be it remembered, are themselves logical 

 matters. Indeed, some psychologists have gone so far as to claim 

 that the distinction of a fact as mental is a purely logical distinc- 

 tion. This is significant as indicating that the time has not yet come 

 for the identification of logic and psychology. 



In refreshingly sharp contrast to the vagueness and uncertainty 

 which beset the definition of a mental fact are the palpable concrete- 

 ness and definiteness of knowledge itself. Every science, even history 

 and philosophy, are instances of it. What constitutes a knowledge 

 ought to be as definite and precise a question as could be asked. 

 That logic has made no more progress than it has in the answer to it 

 appears to be due to the fact that it has not sufficiently grasped the 

 significance of its own simplicity. Knowledge has been the important 

 business of thinking man, and he ought to be able to tell what he does 

 in order to know, as readily as he tells what he does in order to build 

 a house. And that is why the Aristotelian logic has held its own so 

 long. In that logic, " the master of them that know " simply rehearsed 

 the way he had systematized his own stores of knowledge. Naturally 

 we, so far as we have followed his methods, have had practically 

 nothing to add. In our efforts to improve on him, we have too often 

 left the right way and followed the impossible method inaugurated 

 by Locke. Had we examined with greater persistence our own 

 methods of making science, we should have profited more. The 

 introduction of psychology, instead of helping the situation, only 

 confuses it. 



Let it be granted, however, in spite of the vagueness of what is 

 meant by a mental fact, that logical processes are also mental pro- 

 cesses. This fact has, as I have already suggested, an important 

 bearing on their genesis, and sets very definite limits to the freedom 

 of thought in creating. It is not, however, as mental processes that 

 they have the value of knowledge. A mental process which is know- 

 ledge purports to be connected with something other than itself, 

 something which may not be a mental process at all. This connection 

 should be investigated, but the investigation of it belongs, not to 

 psychology, but to logic. 



I am well aware that this conclusion runs counter to some meta- 

 physical doctrines, and especially to idealism in all its forms, with the 



