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!


Istvan Aranyosi said...

Hi and Happy New Year!

I think an attempt at making the idea of a dependence in the other direction more plausible could point out first that experience is not always discriminative among alternative world structures, and second that in such cases it is modal facts that determine the objective structure.

As an example, consider Primitivism about de re modal properties. One such theory is that proposed by Laurie Paul in some papers („Logical Parts”, „Coincidence as Overlap”), according to which modal properties of objects are just a certain kind of parts of them. These properties are not grounded in the actual structure, yet they are parts of it. Arguably then there could be cases, at least as far as experience is concerned, when the same actual world structural facts are consistent with various modal facts, while difference in actual world structural facts will generate difference in modal facts.

Al said...

I think your take on the interplay of 1) and 2) is spot on. It neatly diverts attention to the hard question in this subject - the metaphysical relation between modal facts and actual facts.

I'm worried, though, about a complication concealed within the phrases 'the world's structure' and 'structural facts about the actual world'. Presumably the world's structure includes its causal structure, and on most accounts causal structure *is* modal structure. Structural facts about the actual world that are entirely non-modal would seem to be limited to Lewis-style patterns of occurrent properties, which most people think fail to do justice to the counterfactual elements of our scientific claims.

The most natural way to patch up this suggestion would be to expand 'the world's structure' to include the modal features of actual objects and processes. I think the previous comment suggests something like this, along with a primitivist account of those modal features. But this reintroduces mysterious elements: how does experience give us access to those primitive modal features?

So my worry is that things aren't as easy as they look for an account which makes modal facts metaphysically dependent on actual facts. Unless we have a good explanatory theory of how modal facts depend on the actual facts (eg Armstrong's recent attempt in 'Truthmakers'), or we have a theory of how we can have experiential access directly to modal facts, then there's still no obvious connection between what we do when we attempt to conceive and what we can access through experience.