Now this is true not only of quite empty terms but of terms that carry a meaning. It is a mental necessity that we should make classes and use general terms, and as soon as we do that we fall into immediate danger of unjustifiably increasing the intension of these terms. You will find a large proportion of human prejudice and misunderstanding arises from this universal proclivity. 1.7. NEGATIVE TERMS. There is a particular sort of empty terms that has been and is conspicuously dangerous to the thinker, the class of negative terms. The negative term is in plain fact just nothing; “Not-A” is the absence of any trace of the quality that constitutes A, it is the rest of everything for ever. But there seems to be a real bias in the mind towards regarding “Not-A” as a thing mysteriously in the nature of A, as though “Not-A” and A were species of the same genus. When one speaks of Not-pink one is apt to think of green things and yellow things and to ignore anger or abstract nouns or the sound of thunder. And logicians, following the normal bias of the mind, do actually present A and not-A in this sort of diagram:-- (the letter A inside a circular boundary, together with the words Not A, all inside a bigger circular boundary.) ignoring altogether the difficult case of the space in which these words are printed. Obviously the diagram that comes nearer experienced fact is:-- (the word Not, followed by the letter A inside a circular boundary, followed by the letter A) with no outer boundary. But the logician finds it necessary for his processes to present that outer Not-A as bounded (Vide e.g. Kayne’s “Formal Logic” re Euler’s diagrams and Immediate Inferences.), and to speak of the total area of A and Not-A as the Universe of Discourse; and the metaphysician and the commonsense thinker alike fall far too readily into the belief that this convention of method is an adequate representation of fact.