Vallicella on Existence . . .
My cyber-buddy Bill Vallicella has an excellent post on the use of "is" as copula and "is" as existence, which he gets at via Jean Paul Sartre's novel of metaphysical ideas, Nausea, with its famous scene in which the protagonist, Roquentin, experiences an epiphany on the reality of "existence":
Never, until these last days, had I understood the meaning of 'existence.' I was like all the others, like the ones walking along the seashore, all dressed in their spring finery. I said, like them, 'The ocean is green; that white speck up there is a seagull,' but I didn't feel that it existed or that the seagull was an 'existing seagull'; usually existence hides itself. It is there, around us, in us, it is us, you can't say two words without mentioning it, but you can never touch it. (p. 127, tr. Lloyd Alexander)Bill then explicates this insight of Sartre's protagonist:
'The sea is green' and 'The green sea exists' are logically equivalent. But this equivalence rests on a tacit presupposition, namely, that the sentences are to be evaluated relative to a domain of existing items. The reason we can make the deflationary move of replacing the latter sentence with the former is because existence is already present, though hidden, in 'The sea is green.' 'The sea is green' can be parsed as follows: The sea is (exists) and the sea (is) green, where the parentheses around 'is' indicate that it functions as a pure copula, a pure predicative link and nothing more. The parsing makes it clear that the 'is' in 'The sea is green' exercises a dual function: it is not merely an 'is' of predication: it is also an 'is' of existence. Therefore, translation of 'The green sea exists' as 'The sea is green' does not eliminate existence . . .Bill is an analytic philosopher, but he's here taking the side of continental philosophers, arguing for a "thick" theory of existence ("is" as existence) against the analytic philosophers' "thin" theory of existence ("is" as copula). This distinction is interesting in itself, at least for some of us poor souls, but it has larger philosophical implications, particularly for ontology and theistic questions.
Clearly, Bill is more than logician; he is metaphysician. Go to his blog post for more, or to his book, A Paradigm Theory of Existence, for even more.