Semantics for nihilists

Microphysical mereological nihilists believe that only simples exist—things like leptons and quarks, perhaps. You can be a mereological nihilist without being a microphysical mereological nihilist (e.g. you can believe that ordinary objects are simples, or that the whole world is one great lumpy simple. Elsewhere I use this observation to respond to some objections to microphysical mereological nihilism). But it’s not so much fun.

If you’re a microphysical mereological nihilist, you’re likely to start getting worried that you’re committed to an almost universal error-theory of ordinary discourse. (Even if you’re not worried by that, your friends and readers are likely to be). So the MMN-ists tend to find ways of sweetening the pill. Van Inwagen paraphrases ordinary statements like “the cat is on the mat” into plural talk (the things arranged cat-wise are located above the things arranged mat-wise”). Dorr wants us to go fictionalist: “According to the fiction of composition, the cat is on the mat”). There’ll be some dispute at this point about the status of these substitutes. I don’t want to get into that here though.

I want to push for a different strategy. The way to do semantics is to do possible world semantics. And to do possible world semantics, you don’t merely talk about things and sets of things drawn from the actual world: you assign possible-worlds intensions as semantic values. For example, the possible-worlds semantic value of “is a cordate” is going to be something like a function from possible worlds to the things which have hearts in those worlds. And (I assume, contra e.g. Williamson) that there could be something that doesn’t exist in the actual world, but nevertheless has a heart. I’m assuming that this function is a set, and sets that have merely possible objects in their transitive closure are at least as dubious, ontologically speaking, as merely possible objects themselves.

Philosophers prepared to do pw-semantics, therefore, owe some account of this talk about stuff that doesn’t actually exist, but might have done. And so they give some theories. The one that I like best is Ted Sider’s “ersatz pluriverse” idea. You can think of this as a kind of fictionalism about possiblia-talk. You construct a big sentence that accurately describes all the possibilities. Statements about possibilia will be ok so long as they follow from the pluriverse sentence. (I know this is pretty sketchy: best to look at Sider’s version for the details).

Let’s call the possibilia talk vindicated by the construction Sider describes, the “initial” possibila talk. Sider mentions various things you might want to add into the pluriverse sentence. If you want to talk about sets containing possible objects drawn from different worlds (e.g. to do possible world semantics) then you’ll want to put some set-existence principles into your pluriverse sentence. If you want to talk about transworld fusions, you need to put some mereological principles into the pluriverse sentence. If you add a principle of universal composition into the pluriverse sentence, your pluriverse sentence will allow you to go along with David Lewis’s talk of arbitrary fusions of possibilia.

Now Sider himself believes that, in reality, universal composition holds. The microphysical mereological nihilist does not believe this. The pluriverse sentence we are considering says that in the actual world, there are lots of composite objects. Sider thinks this is a respect in which it describes reality aright; the MMN-ist will think that this is a respect in which it misdescribes reality.

I think the MMN-ist should use the pluriverse sentence we’ve just described to introduce possibilia talk. They will have to bear in mind that in some respects, it misdescribes reality: but after all, *everyone* has to agree with that. Sider thinks it misdescribes reality in saying that merely possible objects, and transworld fusions and sets thereof, exist—the MMN-ist simply thinks that it’s inaccuracy extends to the actual world. Both sides, of course, can specify exactly which bits they think accurately describe reality, and which are artefactual.

The MMN-ist, along with everyone else, already has the burden of vindicating possibilia-talk (and sets of possibilia, etc) in order to get the ontology required for pw-semantics. But when the MMN-ist follows the pluriverse route (and includes composition priniciples within the pluriverse sentence), they get a welcome side-benefit. Not only do they gain the required “virtual” other-worldly objects; they also get “virtual” actual-worldy objects.

The upshot is that when it comes to doing possible-world semantics, the MMN-ist can happily assign to “cordate” an intension that (at the actual world) contains macroscopic objects, just as Sider and other assign to “cordate” an intension that (at other worlds) contain merely possible objects. And sentences such as “there exist cordates” will be true in exactly the same sense as it is for Sider: the intension maps the actual world to a non-empty set of entities.

So we’ve no need for special paraphrases, or special-purpose fictionalizing constructions, in pursuit of some novel sense in which “there are cordates” is true for the MMN-ist. The flipside is that we can’t read off metaphysical commitments from such true existential sentences. Hey ho.

(cross-posted on Metaphysical Values)

Illusions of gunk

I’ve just finished revisions to my “Illusions of gunk” paper. This defends microphysical mereological nihilists (folks who think that the only particulars that exist are microphysical simples) against Ted Sider’s argument that they run into gunky trouble.

The paper is up here, and the abstract follows:

The possibility of gunk has been used to argue against mereological nihilism. This paper explores two responses on the part of the microphysical mereological nihilist: (1) the contingency defence, which maintains that nihilism is true of the actual world; but that at other worlds, composition occurs; (2) the impossibility defence, which maintains that nihilism is necessary true, and so gunk worlds are impossible. The former is argued be ultimately unstable; the latter faces the explanatorily burden of explaining the illusion that gunk is possible. It is argued that we can discharge this burden by focussing on the contingency of the microphysicalist aspect of microphysical mereological nihilism. The upshot is that gunk-based arguments against microphysical mereological nihilism can be resisted.

One thing that I argue for in the paper is that microphysical mereological nihilists are committed to a more far reaching error-theory than you might initially have thought: not only are there no cats and dogs (or compound objects), but there could not have been cats and dogs (or compound objects). I mention in a footnote that this seems to me a real problem for the “counterfactual” fictionalist strategy that Cian Dorr favours to explicate nihilism. Basically, if “cat” isn’t even assigned an intension (as I argue), then “were things to compose but the arrangement of subatomic particles to be exactly as it actually is, then there’d be cats” will be false.

There are problems for alternatives to Dorr’s account too (e.g. I never understood what sense Van Inwagen is supposed to make out of English plural sentences such as “some authors admire only one another”). One future project of mine is to develop a way of doing vanilla possible world semantics in a nihilist world, by tweaking the story about how possible worlds, and possibilia, are constructed…

Phil studies

Those nice people at Philosophical Studies (NB: no url link, because I haven’t found a way to link to specific springerlink journals) have just let me know that they will publish my paper on conversation and conditionals. What makes me particularly happy about this is that I whiled away many happy hours as a phD student playing “hunt the Stalnaker explanation” (Agustin Rayo being the guilty party who introduced me to this strangely addictive game…)

The idea is simple. The idea is to explain as many philosophical puzzles as possible using Bob Stalnaker‘s conversational dynamics. The consummate player is, of course, Stalnaker himself: read the papers in his Context and Content for the paradigmatic examples, including e.g. compelling explanations of what’s going on with Kripke’s puzzling Pierre, negative existentials, Referential/attributive distinction.

At the time, I was particularly keen to use it to try and explain some stuff about de re belief reports (for the cogniscienti: I was looking at Kaplan’s “youngest spy” counterexample to Quine’s principle of universal exportation). To my regret, I couldn’t make it work, and fell back in the end on using Gricean stuff rather than Stalnakerian stuff in the paper that resulted (and I always find relying on Grice unsatisfying, since I never understood where the various “cooperative maxims” come from).

Anyway, the conditionals paper makes use of the Stalnakerian framework to explain a couple of puzzles about conditionals: in particular, showing how to explain away “Sobel” and “reverse Sobel sequences” on any account of conditionals at least as strong as the material conditional; and showing how to explain away the “Gibbard phenomenon” on my favoured implementation of the Stalnaker-style “closest-worlds” account of the semantics of the indicative conditional.

folding up posts on blogger

I’ve been playing around with a blogger hack that allows short summaries of posts to be displayed on the main blog page: with full posts appearing when you view the main post (they appear “below the fold”.

It seems nicer to me: maybe others disagree. The only bit that irritates me is that you don’t get any indication, from viewing what appears on the main page, whether or not there’s extra content “below the fold”. So you have to write this in yourself.

Against against against vague existence

Carrie Jenkins recently posted on Ted Sider‘s paper “Against Vague Existence“.

Suppose you think it’s vague whether some collection of cat-atoms compose some further thing (perhaps because you’re a organicist about composition, and it’s vague whether kitty is still living). It’s then natural to think that there’ll be corresponding vagueness in the range of (unrestricted) first order quantifier: it might be vague whether it ranges over one billion and fifty five thing or one billion and fifty six things, for example: with the putative one billion and fifty-sixth entity being kitty, if she still exists. Sider thinks there are insuperable problems for this view; Carrie thinks the problems can be avoided. Below the fold, I present a couple of problems for (what I take to be) Carrie’s way of addressing the Sider-challenge.

Sider’s interested in “precisificational” theories of vagueness, such as supervaluationism and (he urges) epistemicism. The vagueness of an expression E consists in there being multiple ways in which the term could be made precise, between which, perhaps, the semantic facts don’t select (supervaluationism), or between which we can’t discriminate the uniquely correct one (epistemicism). (On my account, ontic vagueness turns out to be precisificational too). The trouble is alleged to be that vague existence claims can’t fit this model. One underlying idea is that multiple precifications of an unrestricted existential quantifier would have to include different domains: perhaps precisification E1 has domain D1, whereas precisification E2 has domain D2, which is larger since includes everything in D1, plus one extra thing: kitty.

But wait! If it is indeterminate whether kitty exists, how can we maintain that the story I just gave is true? When I say “D2 contains one extra thing: kitty”, it seems it should be at best indeterminate whether that is true: for it can only be true if kitty exists. Likewise, it will be indeterminate whether or not the name “kitty” suffers reference-failure.

Ok, so that’s what I think of as the core of Sider’s argument. Carrie’s response is very interesting. I’m not totally sure whether what I’m going to say is really what Carrie intends, so following the standard philosophical practice, I’ll attribute what follows to Carrie*. Whereas you’d standardly formulate a semantics by using relativized semantic relations, e.g. “N refers to x relative to world w, time t, precification p”, Carrie* proposes that we replace the relativization with an operator. So the clause for the expression N might look like: “At world w, At time t, At precisification p, N referes to x”. In particular, we’ll say:

“At precisfication 1, “E” ranges over the domain D1;
At precisification 2, “E” ranges over the domain D1+{kitty}.”

In the metalanguage, “At p” works just as it does in the object language, binding any quantifiers within its scope. So, when within the scope of the “At precisification 2” operator, the metalinguistic name “kitty” will have reference, and, again within the scope of that operator, the unrestricted existential quantifier will have kitty within its range.

This seems funky so far as it goes. It’s a bit like a form of modalism that takes “At w” as the primitive modal operator. I’ve got some worries though.

Here’s the first. A burden on Carrie*’s approach (as I’m understanding it) will be to explain under what circumstances a sentence is true. usually, this is just done by quantification into the parameter position of the parameterized “truth”, i.e.

“S” is true simpliciter iff for all precisifications p, “S” is true relative to p.

What’s the translation of this into the operator account? Maybe something like:

“S” is true simpliciter iff for all precisifications p, At p “S” is true.

For this to make sense, “p” has to be a genuine metalinguistic variable. And this undermines some of the attractions of Carrie*’s account: i.e. it looks like we’ll now the burden of explaining what “precisifications” are (the sort of thing that Sider is pushing for in his comments on Carrie’s post). More attractive is the “modalist” position where “At p” is a primitive idiom. Perhaps then, the following could be offered:

“S” is true simpliciter iff for all precisification-operators O, [O: “S” is true].

My second concern is the following: I’m not sure how the proposal would deal with quantification into a “precisification” context. E.g. how do we evaluate the following metalanguage sentence?

“on precisification 2, there is an x such that x is in the range of “E”, and on precisification 1, x is not within the range of “E””

The trouble is that, for this to be true, it looks like kitty has to be assigned as the value of “x”. But the third occurence is within the scope of “on precisification 2”. On the most natural formulation, for “on precisification 2, x is F” to be true on the assignment of an object to x, x will have to be within the scope of the unrestricted existential quantifier at precisification 1. But Kitty isn’t! There might be a technical fix here, but I can’t see it at the moment. Here’s the modal analogue: let a be the actual world, and b be a merely possible world where I don’t exist. What should the modalist say about the following?

“At a, there is an object x (identical to Robbie) and At b, nothing is identical to x”

Again, for this to be true, we require an open sentence “At b, nothing is identical to x” to be true relative to an assignment where some object not existing at b is the value of “x”. And I’m just not sure that we can make sense of this without allowing ourselves the resources to define a “precisification neutral” quantifier within the metalanguage in reference to which Sider’s original complaint could be reintroduced.

Being doctored, and might counterfactuals

Last week there was a reunion of the PhD students from St Andrews, five of whom (myself included) worked at the Arche centre. In an act of coordination rarely seen among philosophers, we managed to all get our dissertations submitted and passed within a few months of each other, and so everyone was able to graduate at the same time.

I have to say, it’s kinda funky being an official “doctor”. Leastwise, I now have ways to distinguish myself from the other Robbie Williams. One thing I did while up in St Andrews was give a talk about “might” counterfactuals (continued below the fold).

While at St Andrews, I gave a talk on “might” counterfactuals based on this paper, defending the claim that there are cases where both “If p, it might be that not q” and ” If p then it would be that q” are true. If that’s right, then an argument that Lewis uses against “conditional excluded middle” doesn’t work. And I like conditional excluded middle). The issue ends up turning on attitudes to the lottery paradox, and how exactly we formulate modal constraints on knowledge (safety, sensitivity etc).

After reading a paper that Antony Eagle has just put up online, I’m getting more and more interested in these “might” counterfactuals—it feels like I’m just looking at the tip of an iceberg at the moment. Antony’s paper is highly recommended, by the way: it’s central theme is to explain why it sounds bad to assert the “if p, would be that q, but if p, might be that not q”. I really owe an opinion on this issue myself, as my position in the paper I gave was exactly to argue for the truth of instances of this claim (Carrie Jenkins was acting as my conscience on this point while I was up in St Andrews). Possibly more on this later, therefore…

Work in progress

I’ve rewritten my paper on supervaluational consequence . Material from the blog post below is now included in a separate section. The basic moral is this: (a) supervaluationalists (at least those guys who identify truth with supertruth) do need to go with global consequence rather than local consequence, as Williamson always insisted. But (b) contra orthodoxy, global consequence doesn’t give you counterexamples to familiar logical rules like contraposition and reductio. (There is a proviso, which is obliquely discussed here).

I’ve also revamped my work in progress page, which contains versions of forthcoming papers and a fair amount of genuine work-in-progress. I’m in the camp of people who put up drafts online pretty quickly. I’ve got a tendancy to work up something in draft and then let it languish on my hard disk for months or years… putting papers online is a pretty good reminder system, and also strong motivation not to let stuff sit around with errors in it.

Pro globalization

Writing the last post reminded me of something that came up when I was last up in St Andrews visiting the lovely people at Arche (doubly lovely that time since they gave me a phD the same week). While thinking about stuff presented by (among others) Achille Varzi, Greg Restall and Dominic Hyde, I suddenly realized something disturbing about super and sub-valuationists notions of “local validity”. (Local validity, by the way, is important because everyone accepts that *its* not revisionary. The substantial question is whether *global* validity is revisionary. Lots of people think it is, and I’m inclined to think not). Below the fold, I explain why….

It’s easiest to appreciate the worry in the dual “subvaluationist” setting. Take a standard sorites argument, taking you from Fa, through loads of conditional premises, to the repugnant conclusion Fz. Now the standard subvaluationist line is that though every premise is (sub-)true, the reasoning is invalid (*global* subvaluational consequence departs from classical consequence on multi-premise reasoning of just this sort.). But local validity matches classical validity even on multi-premise reasoning (details are e.g. in the paper Achille Varzi presented to Arche).

Problem! We’ve got a valid argument with true premises, whose conclusion is absurd (and in particular, it’s not true: even a dialethist can’t accept it). It really doesn’t come much worse than that.

You can reconstruct the same problem for a supervaluationist using local validity, if you take multi-conclusion logic seriously. And you should. It addresses this question: if you’ve established that a load of propositions fail to be true, what can you conclude? If the conclusions C follow from the premises A, then if each of the conclusions are “rejectable” (fails to be true) one of the premises is rejectable (fails to be true).

Take a sorites series a, b, c,….,z and consider the following set of formulae: {Fa&~Fb; Fb&~Fc; ….;Fy&~Fz}. In a classical multi-conclusion setting, the premises {Fa, ~Fz} entail this set of conclusions. The result therefore carries over to a supervaluationist setting under local validity (but – crucially – not with global validity).

Now, each of the conclusions is really bad (only an epistemicist could buy into one of them). For the supervaluationist, they’re each rejectable. So one of the premises must be rejectable too. But of course, neither is.

Either way, this seems to me pretty devastating for “local validity” fans. (NB: I chatted about this to Achille Varzi, and he’s put forward a response in the footnotes of the paper cited above. I don’t think it works, but it raises some really nice questions about what we want a notion of consequence for.)

Illusions of validity

I seem to spend loads of time thinking how to defend supervaluationism these days. That’s reasonably peculiar, since I don’t defend its application in many areas: not to vagueness, especially not as a cure-all to the problem of the many (I’m a many-man myself: there are *billions* of mountains around Kilimanjaro). I’m not particularly chuffed with it as a way of handling the inscrutability of reference, either. So basically we’re down to a few bits and pieces: perhaps partially defined predicates, perhaps theoretical terms (though even there I have my doubts).

I do like the spirit of the thing, though, and some relatives of supervaluationism appeal to me as a way of thinking about vagueness (e.g. Edgington-style degree theory).I also like something isomorphic to supervaluationism as a way of thinking about ontic indeterminacy and the like. So I’ve got some investment in it. (continued below the fold)

I’ve recently had a go at defending supervaluationism from the charge that it’s logically revisionary. My line, in affect, is that the arguments that it’s revisionary (most famously pushed by Tim Williamson in the marvelous “Vagueness” book) work only if you think “definitely” is a logical operator. And I can’t see any reason to believe that. (A draft is available here).

Because of this, I was intrigued to find an argument that supervaluationists are (and should be!) logically revisionary in a recent paper by Delia Graff (it’s in the JC Beall “Liars and Heaps” volume). The idea is the following. Suppose that we have a sorites series on the predicate F, and R is an “adjacency” relation along the series. Then from Fa and ~Fb, it should follow for the supervaluationist that ~Rab. For the whole supervaluationist thing is that if there’s a gap between the last F’s and the first ~F’s. But the contrapositive principle (simplifying) is that from Rab you can get ~(Fa v~Fb). That gives you all you need for a negated-conjunction “long sorites” argument.

I think that defender of non-revisionary supervaluation should say that *in no sense* does ~Rab follow from Fa and ~Fb. Yet *intuitively* it does follow (just repeat it to yourself!). But we’ve come against this sort of situation before: the answer is going to be that we *confuse* the inference from Fa and ~Fb to ~Rab with the inference from Def[Fa] and Def[~Fb] to Def[~Rab]. That inference may well be in goodstanding in some sense (it’s obviously not logically valid, but still…) but we won’t get in trouble if we take the contrapositive to be in equal goodstanding. (My moves here are independently motivated because I’m basically replaying the Fine/Keefe “confusion hypothesis” moves that the supervaluationist (and others) need in order to account for the seductiveness of the sorites (there’s a brief presentation of this here).)

So *I think* the Graff thing doesn’t force us to be revisionists any more than the Williamson arguments. But there’s lots of rich stuff around here: plenty more things to think about.

Restart of this blog!