THE NATURE OF JUDGMENT. 185 seem to have a claim to necessity also, just as it is un- doubtedly universal. Kant speaks of it as ' a rule borrowed from experience ' (ib., p. 34). By this language and by his use of ' Bodies are heavy ' as convertible with it, he would seem to suggest that he would not base its empirical character solely on its extensional interpretation. If, as seems probable, he would allow ' Body is heavy ' or ' Man is mortal,' to be equally empirical propositions, then it is plain that what he calls empirical may involve necessity. It is certain, at all events, that if we are to understand by em- pirical propositions only such as experience can justify, such a proposition as ' All bodies are heavy ' cannot be regarded as empirical. It is based on the proposition ' Body is heavy,' with which, if it is to be used for purposes of inference, it must be regarded as convertible. I assume, therefore, that Kant would not have refused to regard ' Body is heavy ' as an empirical proposition. It would seem certainly to come under his class of ' rules drawn from experience, ' whereas
- All bodies are heavy,' regarded solely as extensional, cannot
be called a rule. The use of this example would seem to lead to important results with regard to the true definition of empirical propositions. But let us first return to ' All bodies are heavy '; since even this would seem to involve in its very meaning an assertion of necessity. If it be taken purely in extension, it must be resolved into ' This body, and that body, and that body, ad infinitum, are, have been and will be heavy '. It involves, therefore, the proposition ' This body is heavy '. But in any proposition of this simple categorical form the notion of substance and attribute is already involved. 1 Wherever a predicate is asserted of a subject, it is implied that the subject is a thing ; that it is something marked by the possession of certain attributes and capable of possessing others. ' This body is heavy ' presupposes, therefore, ' Body is a thing, and heaviness is a mere attribute '. For we could not convert the proposition into ' Heaviness is corporeal '. But that ' Body is a thing,' and that ' Heaviness is an attribute,' would seem to be necessary propositions. We may indeed be mis- taken in supposing that they are true ; but if we were ever to find that heaviness was not an attribute, we should be bound to conclude that it never had been and never would be, not that it was so once but had ceased so to be. All such judg- ments are truly ' thought along with their necessity '. They are as necessary as that 2+2 = 4. The difference between 'Cf. R.V., p. 86.
