Absolute identity seems at first sight to be presupposed in the branch of formal logic called identity theory. Classical identity theory may be obtained by adjoining a single schema to ordinary quantification theory.

It may be seen from the foregoing that Pauline's existence is multiply jeopardized; or rather, that my right to use 'Pauline' as a name, the way I said I was going to, is very doubtful, for I agree with Parmenides that one cannot name what is not there to be named. The words I have used to describe Pauline's various perils are full of what Ryle aptly called "systematically misleading expressions"; but we need not worry about that for the moment-enough (...) for now if the words succeed in bringing the various cases before our minds--and we can tidy up our language as we come to see things more clearly. (shrink)

1. Introductory. The notions of existence and necessity have held the interest of philosophers longer than many other problems in the philosophy of logic. The nature of necessity has been debated since the ancient Greeks; and many philosophers have pronounced their opinions on whether ‘existence is a predicate’. In this essay, I shall discuss the notion of existence. In its planned sequel, the same methods will be applied to the concepts of necessity and possibility.