Page:Philosophical Review Volume 6.djvu/20

4 his conception of the genus may and should simultaneously increase in richness of content and depth of meaning. This is an important psychological fact, and as such should find recognition in any psychological account of the growth of knowledge. A complete 'theory of knowledge' may very well be expected to overlap this portion of genetic psychology. But logic has nothing directly at least, nothing primarily - to do with the varying degrees of knowledge of different indi- viduals or with the different stages in the history of an individual mind. For logic ' extension' ought to mean the total appli- cability of the concept, and ' intension ' the total content or meaning of the concept, if its content were completely known. That is to say, here, as in other cases, logic has to do not with what may happen to be in this or that person's mind, nor even with what, as a matter of fact, is in the mind of the average person, but with an ideal standard of knowledge to which any actual human thought can at best only approximate. It is meaningless to attempt to compare such varying and contingent matters as the number of individual roses, or even the number of species and varieties of rose, that any particular person hap- pens to know of at any moment, with the fulness of the descrip- tion which he could give at the same moment of the genus Rosa. To use and extend the convenient terminology of Dr. Keynes, 1 'subjective intension' and 'subjective extension' are quantities too fluctuating and indeterminate to admit of comparison; whereas 'objective intension' and 'objective extension ' do conceivably at least admit of comparison. For the purpose of illustration and exposition we must be content to take 'conventional intension' and compare it with the actually known applicability of the term. ' Conventional intension ' Dr. Keynes uses for " those attributes which con- stitute the meaning of a name " ; he does not say 'to whom.' I suppose we must understand ' to the average well-informed person of our acquaintance.' This use of ' conventional 1 Formal Logic, 3d ed., pp. 24, 25. The names " subjective and objective exten- sion" which I here suggest, seem to me to express a distinction more useful and important than that which Dr. Keynes draws between denotation and extension on page 31.