Modality without Possible Worlds

Although I don't specialize in metaphysics, I'm perennially interested in it and like to keep on it as much as I can. Anyway, I've read several articles on modality recently that really piqued my interest, and which  and figured it couldn't hurt to share them. The first article I came across is Jonathan Jacobs', "A Powers Theory of Modality: or, How I Learned to Stop Worring and Reject Possible Worlds." Then I read Barbara Vetter's recent paper in Analysis, "Recent Work: Modality without Possible Worlds."

I think (naively, perhaps) that what Vetter calls the "new actualist" approach to modality -- understanding modality in terms of essences or dispositions rather than possible worlds -- may be a real agenda-setting development. So much philosophical argument over the past several decades seems to have been predicated upon what Vetter and Jacobs call a Humean/Lewisean metaphysical picture: a picture where objects and properties bear no necessary connections. What if, as the new actualists suggest, this Humean/Lewisean picture is false? Anyway, I think the stuff is interesting and well worth reading, if only as a stimulating counterpoint to a now orthodox way of thinking.

Comments

[eyeyethink]

Thanks for the sharing Marcus; I hadn't seen the Vetter and I'm glad to know of it.

Yes, new actualism is definitely agenda-setting. But is it a good agenda? Well, like most anything, there's probably some good and some bad. What is especially controversial is the supposition that scientific laws are metaphysically (not just physically) necessary. To my mind, that undermines one of the key reasons to distinguish between physical and metaphysical necessity in the first place (though other reasons remain).

One wants to make sense of counterfactuals where the laws of nature are different. E.g., it is an important scientific truth that "if the strong nuclear force had been 2% stronger than it is, the physics of stars would be drastically different and life as we know it would not exist." So folks usually say that the truth of such a thing is determined by a world that is not physically possible but still metaphysically possible. But with new actualism, there are no longer any metaphysically possible worlds with different laws. So how is the new actualist going to make sense of these counter-nomic statements? (We shouldn't say that their truth is determined by worlds that are merely logically possible. For then the counter-nomic statement has the same modal status as any ole non-contradictory statement).

My own proclivities are more Quinean, but I disagree with Fine's statement (quoted at the beginning of Vetter) that Quine thought modal notions had no sense whatsoever. After all, Quine himself used modal notions in formulating his views (e.g., "any statement is revis*able* in light of recalcitrant experience") But that is a whole other discussion.

[eyeyethink]

(Erratum, Fine-style essentialists are not committed to the metaphysical necessity of laws; I should have spoke of dispositionalists instead of new actualists generally.)

[Marcus Arvan]

eyeyethink: Thanks for your comment, as well as the erratum (I was about to write, in response to your first post, "Wait a minute: not all new actualists take laws to be necessary", but now I don't have to!).

Anyway, I agree with your suggestion that there's probably some good and some bad in the research program. Here are my thoughts at the moment. I think it is probably a mistake to do away with possible worlds altogether. Very different worlds are possible, and a bare form of new actualism can't make adequate sense of this (given that they take modality to be determined by the nature of actual objects and properties).

Here, though, is what I think the actualists have right: there are certain dispositions (or perhaps essences) that should be understood as constraining modal semantics in ways that a *bare* possible worlds approach does not. Allow me to explain.

Here is what I think the new actualists have right. I don't think it is metaphysically possible for *me* to jump tall buildings in a single bound. This is because I am made of protons, neutrons, and electrons, and it is metaphysically impossible for anything made of protons, neutrons, and electrons to do *that*.

I think the new actualists are right in this regard because it seems to me that *I*, essentially, am made of these things. Something made of very different stuff wouldn't be *me*. It would at most be someone *like* me.

But I think we need possible worlds to make sense of *that*. I think it *is* metaphysically possible for someone very much like me -- call him Super-Marcus -- to jump tall buildings in a single bound. But I just don't think it would be *me*. I think it would merely be someone like me.

Anyway, traditional possible worlds theorists will say (as you suggest) that the first part of this collapses metaphysical and physical possibility. But this is what I think new actualists have *right*. There is a sense in which, given my essence, metaphysical modal truths about me are restricted by my *actual* composition. Where I think new actualists go wrong is in wanting to say this is all there is and get rid of possible worlds.

In short, I'm inclined, at least for now, to think that neither traditional possible-worlds modal semantics nor new actualism are right. The right view, rather, is a combination of the two: a possible-worlds semantics *constrained* by dispositions or essences.

What do you think?

[A.P. Taylor]

Marcus, along the same lines, you might want to check out Williams and Borghini (2008) "A Dispositional Theory of Possibility" in Dialectica 62: 21=41.

[eyeyethink]

Hi Marcus,
Thanks for your remarks. It seems, however, that according to you the relevant modal truths are restrained not merely by your actual composition. It's also that, apparently, they are restrained by the actual laws that govern your particle-parts (or at least some of those laws). But again, there seem to be important truths about what happens if such laws were different.

Maybe there's a trade-off and it's ultimately better to go your route. But it seems you would be giving up something in the trade...