Monday, August 01, 2005

More on Vague Existence

Here's a more concise (and otherwise improved) version of a worry I was playing about with in my post a few days ago, and a look at a couple of manouevres that might be made in response.

There is a tension between the following three claims:
1. One is committed to Fs iff there are Fs among the range of the quantifiers appearing in one's best theory.
2. According to best theory, it is an ontically vague matter whether an F exists.
3. Someone whose best theory (correctly) asserts that it is a vague matter whether an F exists isn’t committed to saying that an F exists, nor is she committed to saying that one does not exist.

By 3, if 2 is true then we are not committed to the existence of an F. By 1, therefore, no F is among the range of the quantifiers appearing in our best theory. Hence our best theory can also truly contain the sentence ‘Nothing is an F’. But how can it be that our best theory can truly assert both that it is a vague matter whether or not there is an F and that nothing is an F? If nothing is an F, then it is not a vague matter whether or not there is an F: it is settled that there isn’t one.

Short of ditching 1 altogether, there seem to be two possible lines of response which a defender of 2 could appeal to. One is to argue (contra 3) that it is a vague matter whether the defender of vague existence is committed to Fs. The other is to revise 1 so that it reads: one is committed to Fs iff, determinately, there are Fs among the range of the quantifiers appearing in one's best theory.

I don’t find the first response appealing; acknowledging ontic vagueness seems to me to be a paradigmatic way of remaining decidedly non-committal. The second, though, may be thought more promising. Given that the defender of vague existence for Fs is not committed to Fs, the revised version of 1 will only deliver that it is not determinately true that there are Fs among the range of the quantifiers appearing in her best theory. This won’t entail that her best theory can truly say ‘Nothing is an F’.

However, some independent motivation for the revision is needed if it is not to appear ad hoc. And I'm not sure what form that motivation might take. There doesn’t seem (for all that’s been said here) to be anything wrong with the original 1 except that it makes claims of vague existence problematic. But until we are persuaded that vague existence is actually unproblematic, why should we regard that as a reason to revise 1?


Brian Weatherson said...

Could you say more about what work 'ontically' is doing here? As it stands, the argument seems to prove too much.

Say there is one person in the common room, and he is a borderline case of baldness. Let F be the predicate 'a bald person in the common room'. I think it's a vague matter (not an ontically vague matter, but vague) whether there are any Fs. So I'm not committed to the existence of Fs. So, by 1, my quantifiers can't include any Fs. So there are no Fs. But hang on, we said it was vague whether there are Fs!

I'm inclined to think your argument works and this little argument doesn't, but I'd like to know more about just where the differences are.

Carrie Jenkins said...

Hi Brian,

Funky objection!

Well, one thing some linguistic theorists of vagueness might like to say is that best theory will/should eradicate vague predicates.

But even if we're not going to be *that* kind of linguistic theorist, I think I can see how there could be principled reasons for linguistic theorists to restrict 1 to cases where F is non-vague. After all, they could say, 1 is a principle about what (we're committed to saying) is really out there, and the vagueness of the vague predicates we use has nothing to do with what (we think) is really out there. So vague predicates are bound to lead you astray if you plug them into 1, just as they would if you took them to be guides in other ways to what we think the world is really like - e.g. if you took us to be committed to a real vague property of baldness just because the predicate 'bald' appears in our best theory.

Elizabeth said...

Cool stuff. . .I don't think your revision of (1) is ad hoc, precisely because you've got the motivations for revising it as such based on the vagueness worries you've already covered. If you're going the Quinean route (silly Quineans. . .), then I don't think you're pressured to find 'independent motivation' for an ammendment to (1). Sure, (1) looks fine by itself, before you start fussing about vagueness, but once you've brought those issues to bear then (1) appears problematic. If you're fully Quinean though, even basic principles like (1)-(3) aren't going to be immune from revision based on considerations elsewhere, so worries about how (1) handles problems of vagueness ought to be precisely the sort of thing that would give you motivation to change it, without worries that you're being ad hoc -- provided you think that your best theory is one which says that ontic vagueness is the sort of thing you ought to be able to handle.

Elizabeth said...

Also, I love that in leaving comments on your blog I get to click 'publish'. It makes me feel like I've accomplished something (when in point of fact I've only put off a paper I really don't feel like writing at the moment; I love the internet).

Carrie Jenkins said...

Hi Elizabeth,

I know - it's fun to think that I've been 'publishing' on a daily basis for a while now ...

I guess the problem with revising 1 in response to the points about vagueness that I mentioned is that it's not going to help persuade anyone who thinks, for the reasons I gave, that vague existence is confused. Unless one already thinks that vague existence has something going for it, there isn't any motivation for the reivision. On the contrary, if your intuition is that vague existence makes no sense, you can just chalk this one up as another bit of helpful clarifying work done by (the unrevised) 1.

There isn't going to be a knock-down argument against vague existence here - more likely a stand-off. I agree that if your instinct was that vague existence was OK my argument might give you enough of a motivation for revising 1. (I think that would by itself be quite an interesting response, though!)

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