Sunday, December 18, 2005

Chalmers, Carnap and Lightweight Existential Quantification

I clicked through to David Chalmers's powerpoint slides on Ontological Indeterminacy yesterday, wondering if I might get a discussion of ontic vagueness. In fact I found something else equally interesting: a discussion of 'deflationary' (=, roughly, Carnapian) views about certain existential questions.

I have a few comments (though NB I have not heard the full talk, so maybe some of these points are addressed there):

1. I'm not sure whether the kind of 'relativism' Chalmers describes should count as deflationary. To say that there are many equally good answers to a question (which I think is the core of the proposed 'relativism') is prima facie different from saying that there is *no* substantial answer to the question (deflationism). To get the latter from the former we seem to need to assume that relativism about answers to a question is incompatible with the thought that the question and its answers are metaphysically substantial.

2. I think substantial ontological existence claims can be what Chalmers calls 'lightweight', i.e. a priori knowable or analytic or something in that area. Which is to say, in effect, that I don't think 'lightweight' (a priori knowable) existential claims need be genuinely lightweight. The envisaged connection between 'lightweightness' and real , metaphysical, lightweightness is, I guess, supposed to be effected by the thought that a priori reflection can only address what Carnap would call 'internal' questions, while genuinely heavyweight ontological questions must be 'external'. But personally (for what it's worth), I think concept-led a priori reflection might well lead to knowledge of substantial conclusions, including existential conclusions. Once we acknowledge that concepts can be grounded - i.e. sensitive to the way the world is in such a way as to make them good epistemic guides to reality - we can think (in Carnapian terms) of frameworks as being selected on more-than-pragmatic grounds, that is, selected for their fit with the world. And then there is no reason to doubt that a priori reflection on concepts within a framework can give us epistemically respectable answers to (what Carnap would have called) external questions.


djc said...

Hi Carrie, I suspect that the first issue is somewhat terminological on "deflationary". Certainly there's a pretty natural sense in which a relativist view is less robustly realist than a non-relativist view. But of course robustness of realism has many dimensions. Hirsch's version of relativism is also "lightweight" in the more specific sense in my paper, in that his version holds that existential truths are analytically entailed by non-existential truths.

As fo the second issue, my use of "lightweight" was also meant to be somewhat stipulative. But I agree that it's coherent for a very robust ontological realist to hold that existential truths can be known a priori. So the lightweight/heavyweight distinction shouldn't be cast in terms of apriority. It's more naturally cast in terms of something like analyticity. I know I mentioned apriority as well as analyticity and conceptual necessity on the relevant slide (in the talk, I mentioned these three options for casting the distinction and then just said that the choice between them is somewhat complex), but I think it's better to focus on notions like the latter.

Let's say that existential quantification is lightweight if there are analytic existential claims, or if existential claims can be analytically entailed by non-existential claims (this definition might need to be refined, but this gives the idea). Then many people doing substantial ontology will deny that existential quantification is lightweight, and they'll say that any reading of quantified claims according to which the quantifier is lightweight isn't the reading that's relevant to ontology. Some people doing ontology, such as Wright/Hale and Jackson, will disagree with this, holding that ontologically relevant existential quantification is lightweight. But it's pretty natural to see these people as lightweight ontological realists, compared to heavyweight realists such as Sider and van Inwagen.

Of course, it's natural enough for a heavyweight realist to hold that existential claims can be known a priori, e.g. through some sort of rational insight or even through abductive a priori reasoning. But presumably they'll hold (if they talk this way) that the relevant claims are at best something like synthetic a priori, rather than being analytic.

Carrie Jenkins said...

Hi David,

Thanks for the comments.

"Certainly there's a pretty natural sense in which a relativist view is less robustly realist than a non-relativist view."

I'm not sure I see that. Suppose you're the kind of relativist who thinks there are many (fully real, fully robust) realities. I don't see how moving from one reality to many moves you along *any* realism/anti-realism axis - why can't you adopt a maximally realist view about each of the realities you end up with?

On lightweightness, I don't think analyticity or conceptual necessity would do it for me either, for the same reasons. Re: analyticity, I don't think conventionalist, 'made true just by meanings'-type, analyticity is a useful notion (nothing has that property); as far as I can tell, the only respectable notion around here is something epistemic - 'knowable just through knowledge of meaning' perhaps. But I think existential claims with that property can be as ontologically heavyweight as you like, provided you have an epistemological story in place to explain how thinking about meanings/concepts can give you knowledge of (robust) reality. I think it's true that Hale/Wright sound lightweight, but then their epistemological story doesn't tell you how you could get knowledge of heavyweight ontology just by noticing analyticities.

As far as I can tell, I'm a heavyweight realist (one who does not believe in rational insight or, in the relevant cases, appeal to abductive a priori reasoning) who thinks there can be a priori, analytic, conceptually necessary (etc.) heavyweight existential claims!

djc said...

At first hearing, a view that acknowledges "many fully robust realities"sounds like a sort of objective pluralism to me, rather than relativism. E.g. David Lewis had a view like this, and he wasn't a relativist! I suppose that a relativist view might be distinguished from Lewis's view by the claim that utterances or evaluations of existential sentences by different actual people are indexed to different realities. In ontology, I take it that the idea would be that there's e.g. one robust "reality" with numbers, one without numbers, with different speakers/assessors indexed to different realities. I'm not sure I've seen such a view developed -- got a reference? In any case I should acknowledge that I didn't have this sort of pluralism about robust realities in mind when I discussed relativism (I had in mind views with a single reality and some sort of relativism in evaluating utterances about that reality), so my remarks don't apply to it.

Of course there are many ways to draw the analytic/a priori distinction, which is one reason why I said the correct way to cast the lightweight/heavyweight distinction is complex. Certainly a conventionalist construal of analyticity won't do any work. If one wants to construe analyticity in epistemic terms, I think the distinction will amount to something like, trivial vs nontrivial knowability by someone possessing the relevant concepts. (Where triviality comes to something like Fregean cognitive insignificance.) If someone thinks that existential claims are trivially knowable by someone with the relevant concepts (as I think Wright/Hale and Jackson do), then I'll count their view as lightweight. If they think that existential claims are knowable a priori but only through nontrivial reflection involving the relevant concepts, then I'll count the view as heavyweight. Of course around here the distinction is somewhat stipulative, and also inherits the vagueness and imprecision of "trivial". But if you think that there's an intuitive sense of "lightweight" and "heavyweight" according to which this usage misclassifies your view, I'd be interested to hear more about that sense.

Carrie Jenkins said...

"I take it that the idea would be that there's e.g. one robust "reality" with numbers, one without numbers, with different speakers/assessors indexed to different realities"

That's what I was thinking - call it (without prejudice ;) 'crazy relativism'. I don't think it has many defenders ... certainly I didn't have anyone in particular in mind here, just an option in logical space.

Although, reflecting, if all that's needed for relativism in your sense is "a single reality and some sort of relativism in evaluating utterances about that reality" then that seems compatible with a good dose of anti-deflationist realism: you could get that sort of result just by adopting a sort of perspectival view, e.g. saying that there is a single, robust reality out there and different conceptual 'takes' on it render true different ontological claims for different (possible) beings. The core of the view I think you're interested in (certainly what I think Carnap was after) seems to be different from this in that on such a view the perspective/conceptual scheme wholly *creates* the facts, i.e. the facts obtain just in virtue of the conceptual scheme - which is where the anti-realism/deflationism gets into the picture. But it seems to me that claims like this about *dependence* on a scheme should be distinguished from claims about *relativity* to a scheme, since the latter is compatible with the weaker perspectival view where there is some sort of relativity but also a single underlying reality that is what ultimately makes all the relevant utterances true (as well being compatible with 'crazy relativism').

As to the rest, my answer depends on what you intend by 'trivial'. Certainly the kind of view I like will tend to agree with (say) Wright/Hale about how *easy* it is to know about mathematical ontology through conceptual reflection. But I don't think that means the resulting arithmetical ontology is lightweight, if that's to mean something like: Carnap-internal, or that knowledge of it is trivial, if that's to mean something like: only knowledge of a Carnap-internal matter. I think if concepts were grounded in experience of the world there could be a (not-merely-pragmatic) rationale for the selection of concepts, and correspondingly a possibility that what we learn just by noticing analyticities involving these concepts can count as knowledge of a robust reality. (In case you're interested in the details, the relevant paper is 'Knowledge of Arithmetic' available from my home page.)

Anonymous said...

Hey Carrie!
You say, "we can think (in Carnapian terms) of frameworks as being selected on more-than-pragmatic grounds, that is, selected for their fit with the world." I am wondering how this 'fit' between frameworks and the world would be more than pragmatic? It's not clear to me.

I have a feeling that Carnap would say that these 'frameworks' themselves are merely useful fictions.

Isn't a semantic account of correctness itself a fiction with pragmatic value (or not)?

Kind regards,
F. Power