Thursday, June 29, 2006

Against 'Against 'Against Vague Existence''!

Robbie Williams has a response to my post Against 'Against Vague Existence' over on his blog Theories 'n Things.

I've recently written up a short note based on the idea in my original post, which I've put online here. I hope it goes some way to addressing Robbie's concerns (which centre on the thought, shared by Sider, that I need to say something about what kind of thing a precisification is on the envisaged account).

Wednesday, June 28, 2006

Extended Simples and Quantized Space

David Braddon-Mitchell and Kristie Miller have a fun new paper arguing that we can both believe in spatially extended mereological simples and agree that every extended object o has a part at each sub-region of the region which o occupies. The trick which is supposed to enable us to marry these two theses is to claim that space has smallest regions which have no sub-regions. (This is a position I've heard defended in conversation by others as well, so I'm coming round to the view that it ought to be taken seriously.)

For many of us, quantized space seems a very strange idea on the face of it, but Braddon-Mitchell and Miller argue that it must be taken seriously because of certain results in physics. They claim that 'physicists tell us that we cannot divide up space into any finer-grained regions than those constituted by Planck squares [i.e. areas of 10 to the power -66 centimetres squared]' and that physics 'tells us that talk of space breaks down altogether once we talk about regions smaller than the Planck square'. 'Hence', they conclude, 'we know that talking about something occupying a sub-region of a Planck square makes no sense: there is no such sub-region' (p. 224).

When they give a few details of what the physics actually shows, it turns out to be that 'there is nothing that could be taking place within these squares'. Braddon-Mitchell and Miller take it (and this is where I get puzzled) that this 'is to say that in principle, there cannot be anything that occupies the sub-regions of such a square' (p. 224, their emphasis).

For all I know, physicsists may well be claiming this sort of import for that sort of result, but I can't see how the transition could be that straightforward. What I can't understand is how any claim about what can or cannot take place with a Planck square - which is of course the sort of thing physicists can helpfully tell us about - could settle the question of whether such a square has sub-regions. Specifically, I wonder what sort of results are supposed to distinguish between the hypotheses:
1. that Planck squares have no sub-regions
2. that any Planck square (and therefore any sub-region of a Planck square) must, as a matter of nomic necessity, be uniformly filled.

The claim that nothing can be 'taking place' within a Planck square seems at best to get us as far as 2. What justifies the further step to 1? What sort of result from physics as it is currently practiced could possibly justify this further step?

(I ask these questions in self-confessed ignorance of the physics, but with a dose of scepticism as to whether we can get this much metaphysics out of it, whatever it is!)

Tuesday, June 27, 2006

Job News

I've just accepted a job offer from the University of Nottingham. I start there on 1st September, although I will be in Australia until September 2007.

My favourite colleague is also moving to Nottingham. We are sorry to leave behind lots of great colleagues in St Andrews, but are very excited about joining the Nottingham crowd!

Monday, June 26, 2006

Philosophy of Flirting

Just for fun, I've written up a few thoughts on the philosophy of flirting. I'm trying to make progress towards a set of necessary and sufficient conditions for when an act of flirtation has taken place. Let me know what you think!

Wednesday, June 21, 2006

TAR at new address

For those who read Brian Weatherson's blog as well as this one (I imagine an improper subset of those who read this blog), Thoughts Arguments and Rants is now at after the original address was hijacked.

Sunday, June 18, 2006

They'll All Be Concept-Grounding Theorists Soon ...

More evidence that a priori knowledge is hitting the big time again - and that people are starting to ask just the right sorts of questions about it (that is, the questions that motivate my view ... :)

Saturday, June 10, 2006

Infallibility and Modal Epistemology

The Arche Modality Conference has just finished, and has been excellent fun. I've put some photos on my website. In the end, my comments on Scott Sturgeon's talk mainly focussed on the claim that the infallibility of idealized conceivability methods is the wrong focal point for his worry. He's worried that if we are realists, we shouldn't think that metaphysics and epistemology will fit together the way the infallibilist requires - there should be room to make a mistake. For idealized conceivability (as he thinks of it) involves only mental idealization (allowing unlimited time, capacities etc.). How can we have a guarantee of getting a true belief, if we have only idealized these mental processes, and said nothing about their relationship to the world?

But I argued that we still have a worry of the same kind for fallibilist conceivability views. My point here was just an analogue of what we tell students who think Hume’s worries about induction show that we aren’t guaranteed to get true beliefs by inductive methods, but still think these beliefs are likely to be true. What I claimed is that, for the same reasons Sturgeon thinks we should be worried about the infallibility of conceivability, namely because epistemology and realist metaphysics don’t fit together like that, we should also be worried about the claim that it’s likely that conceivability will deliver true beliefs. Epistemology and realist metaphysics don’t fit together like that either – you don’t get good ways of finding out about the independent world when you idealize along only mental dimensions. Good ways of finding out about the independent world require input, which is a world-involving relationship, and not purely mental.

So infallibility is not necessary to generate the problem. In fact, I claimed, it’s not sufficient either. Sturgeon’s worry will go away if we can somehow add a mind-world input element into our account of ideal conceivability. This sort of ideal conceivability can unproblematically be infallible, for the same reasons Sturgeon thinks idealized vision (which is, among other things, always veridical) can unproblematically be infallible.

The deep problem in the vicinity of Sturgeon's worry is a very old one: how can a priori reflection be a source of knowledge of facts which are construed realistically? But of course, there are many answers to this and debates about them which would have to be engaged with before we could claim to have pressed the point in a new way.

Monday, June 05, 2006

Responding to Kripke

Right, I'm back ... minus one appendix. And straight back into the thick of it, with the Arche academic audit starting today. We've had talks by Mark Sainsbury, Paul McCallion, Philip Ebert and Marcus Rossberg (jointly) and Frank Jackson, with topics ranging from famous fictional characters such as Sherlock Holmes to infamous real ones such as Julius Caesar and Timothy Williamson.

In my spare time :) I'm meant to be preparing some comments on Scott Sturgeon's talk at the upcoming Modality Conference, which is based on this paper. He is arguing against the following combination of views:

1. Kripke is right that ideal conceivability does not imply possibility.
2. But we should make minimal adjustments to deal with 1 - i.e. we should hold that ideal conceivability implies possibility except in the particular kinds of case Kripke brings to our attention.

One thing I'm not sure of is whether this combination of views is defended in print by anyone. (Scott doesn't mention anyone in the version of the paper I've seen.) But more interestingly, I wonder whether many people really (perhaps tacitly) think this is the appropriate thing to do.