cbostrum (01/23/83)
Anselm's ontological argument for the existence of God (as recently presented in this group) seems to suffer from severe linguistic confusions. It is normally dismissed (almost rightly so I believe) with the contention that "existence is not a predicate". Ideas involving existence cannot be predicated of things sensibly since the fact that the thing is there to begin with is a presupposition of any predication whatsoever. But ideas involving existence can be predicated of *descriptions* if the idea is that there exists some thing that fills the description. Thus, we would have a predicate defineable in a second order logic (but *not* a first (well, not with standard predication: with predication in a set theory contrued as membership this would be possible)) something like: Exists-A(P) iff (E x) P(x). But it is very important to note the type distinctions before using such a predicate. If existence were a predicate, it wouldnt be useful or interesting, since all things, including perfect ones, would satisfy it. It must only be a predicate of descriptions, and then, there is no way to use it as anselm did. There is a modern variation of anselsms argument which uses modal logic, but I havent analysed it. I would imagine that it suffers from similar flaws.