So here's something that's been puzzling me, and I've made very little progress on. The neo-Carnapian holds that ontological debates are shallow. When two ontologists argue as to whether there are Fs, the neo-Carnapian says that this isn't a genuine ontological debate: that at worst these two theorists are simply talking past one another; at best their disagreement is merely linguisitc, over the correct usage of the English terms involved.
Now, it's obviously trivial that we could use the term 'exists' differently, so that 'there exists an F' would have had the opposite truth value from what it in fact has. We could have meant by 'there exists' what we in fact mean by 'there doesn't exist', for example. That's not interesting. So what is the neo-Carnapian thesis? Sider characterises it, correctly, as the doctrine that there are multiple meanings for the quantifier and that none of them is more natural than any of the others. (Either because there's no such thing as naturalness, or because there is and they're all equally natural.) Okay, but we just used a quantifier to state that: there are multiple meanings for the quantifier that are equally natural. So if neo-Carnapianism is true, wouldn't their own theory tell them that their theory is not a substantial theory: that is, one whose truth is sensitive not to the metaphysics but simply to what we mean by our words? If neo-Carnapianism is false, it's substantially false, but if it's true it's trivial (in one good sense of trivial).
Is that right? And if so, is it a problem for neo-Carnapianism? It's a strange dialectical position to be in, to hold a view that is trivial if true and substantially false if false, but it's not obviously incoherent.
(I've been considering a neo-Carnapian who thinks that all ontologiacal disputes are shallow; of course, many don't - Hirsch, for example, thinks disputes about the existence of complex objects etc are shallow, but not disuputes about the existence of, e.g., numbers and sets. So let the question be: does the above give us reason to reject global neo-Carnapianism: to hold that at least the question as to whether there is a most natural meaning for the quantifier is a substantive ontological question?)