uh. I.] THE RELATIVITY OF KNOWLEDGE. 11 



Secondly, the possibilities of thought are not identical or 

 coextensive with the possibilities of things. A proposition 

 is not necessarily true because we can clearly conceive its 

 terms ; nor is a proposition necessarily untrue because it 

 contains terms which are to us inconceivable. 1 



This great truth, which I have thus illustrated by a few 

 empirical examples, must now be illustrated deductively. It 

 must be shown how the impossibility of knowing or con- 

 ceiving anything save the Eelative results from the very 

 constitution of our minds — from the very manner in which 

 our thinking takes place. And this may be shown by several 

 distinct lines of argument. 



In the first place, all knowing is classifying. What do we 

 mean when we say that any given phenomenon has been 

 explained ? We mean simply that it has been ranked along 

 with similar phenomena which, having previously been 

 grouped together, are said to be understood. For example, 

 in walking out some clear November evening, your attention 

 is arrested by a bright, but suddenly vanishing track of light 

 across the sky, which you recognize as the appearance ol 

 a " falling-star." In doubt, perhaps, as to the true explana- 

 tion of this phenomenon, you appeal to some astronomer, who 

 tells you that a zone of planetary matter encircles the sun ; 

 that the course of this zone, lying near the course of the 

 earth's orbit and not being concentric with it, must intersect 

 it at sundry points ; and that when, at certain seasons of the 



1 Hence, as will appear more fully hereafter, we have no criterion of abso- 

 lute or objective truth. But it will also appear that, in the realm of pheno- 

 mena, with which alone are we practically concerned in forming the conclu- 

 sions which make up our common-sense, our science, and our philosophy, 

 we do possess a valid criterion of relative truth in the test of inconceiv- 

 ability. A proposition concerning phenomena, which contains an incon- 

 ceivable term, is ipso facto a proposition without a basis in cur experience of 

 phenomena, and is accordingly inadmissible. But a proposition concerning 

 noumena, which contains an inconceivable term, is entirely out of relation 

 with experience, since we have no experience of noumena ; and we have 

 accordingly no means of judging whether it is true or noi. This is ^vhat is 

 meant by the statement in the text. 



