Saturday, December 31, 2005

What I'm Doing On My Holidays

I'm writing a paper on modal knowledge over this Christmas/New Year break. In it I'm trying to argue that we can answer two questions simultaneously:

1. How can experience be a guide to modal truth?
2. How can conceivability be a guide to modal truth?

by proposing that experience grounds our concepts (that is, makes them knowledge-conducive guides to the structure of the world), and that what we can conceive of is constrained by what our concepts are like in such a way that the information about the world's structure which is in encoded in the structure of our concepts is recoverable through the activity we call 'attempting to conceive'.

What's all that got to do with knowledge of what's possible and necessary? Well, things are easy if you think that modal facts are , or metaphysically depend upon, structural facts about the actual world. Because the latter are the kinds of facts that 'attempts to conceive' put us in touch with.

What I'm looking at now are ways in which people who don't like that metaphysical idea might also get in on my epistemological act. Ways, that is, in which you might think that information about actual-world structure can be an epistemic guide to modal facts even though these facts do not depend metaphysically on facts about actual-world structure.

One option is to believe in metaphysical dependence in the other direction: that is, to think that actual-world structural facts depend on modal facts. But that option doesn't have much prima facie plausibility (at least, not to me).

Alternatively you might think both actual-world structural facts and modal facts depend on some other class of facts in a way which explains the correlation between the two. (But what sort of facts would they be?)

There's always the option of brute correlation, but we'll need a damn good story about why we should take the correlation to be brute, to tell to those who think that it's actually evidence of metaphysical dependence in one direction or the other.

Finally, I thought, perhaps you might think there is some satisfying explanation of the correlation which does not appeal to metaphysical dependence at all. (But what would it look like?)

As always, any comments/suggestions/further possibilities are very welcome here.

Happy New Year!

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.

Friday, December 09, 2005

Non-trivial Counterpossibles

A reflection that was triggered by hearing Timothy Williamson give a paper here last weekend at the last ever Arché Modality Workshop.

Some people (classically, Lewis) think any counterfactual with an impossible antecedent is trivially true, and I'm prima facie inclined to agree. But we should be able to distinguish between ones where there appears to be something non-trivial going on, such as:
1. If the square root of 2 were rational, it could be represented as n/m with n, m integers
and ones which don't seem to have this feature, such as:
2. If the square root of 2 were rational, there would be lemonade rivers.

Two options are:
A: to say that the difference between trivial and non-trivial counterpossibles is one of assertability (1 is assertable in many contexts where 2 is not),
B: to say that this difference is a matter of epistemic accessibility (you can know 1 is true without knowing it has an impossible antecedent, whereas this looks doubtful for 2).

But I'm currently wondering whether, in some cases at least, neither assertability nor epistemic access gives the deepest or most insightful characterization of the difference - they may rather be symptoms. For instance, you might think that in some cases it is the existence of some metaphysically interesting connection between states of affairs described in 'A' and 'B' that really explains why a counterpossible conditional 'A []--> B' is non-trivially true. You would then expect this conditional to exhibit the pattern of assertability and epistemic accessibility usually associated with non-trivial counterpossibles, although that behaviour is not what its non-triviality amounts to but rather a sign of it.

(PS For the record, I don't assume there will be the same story to tell in every case about what sort of factor underlies the assertability and accessibility symptoms.)

(PPS I will - hopefully - get round to replying to the interesting comments on my previous post soon ...)

Saturday, December 03, 2005


Here's a common claim schema:

If ... is dependent on our language, then were our language to be different in relevant respects then so would ... be.


(1) If vagueness depends on our language, then were all semantic vagueness to be eliminated then there would be no vagueness.

A worry about this is that it seems a semantic theorist of vagueness (someone who thinks vagueness is entirely due to semantic features of our language, and has nothing to do with how the world is independently of our linguistic representations of it) might sensibly reject (1), and instead assert:

(2) Although vagueness depends on our language, if all semantic vagueness were eliminated, this apple would still be borderline red.

For the consequent of the counterfactual is couched in the very language which is supposed to be suitable for creating vagueness. Asserting (2) therefore does nothing to undermine the thought that it is the semantic features of our actual word 'red' language which are responsible for the borderlineness, in other worlds, of the apple's redness.

What do people think?