• Jerry Fodor
• David Chalmers
• Randall Munroe

When we were in Melbourne over Christmas, Ishani and I went to Marysville for a couple of days. We wanted to get out of the city for a little, and spend a little time in the bush and in a pretty country town. It was very pleasant there, especially staying at “Rendezvous Cottages”:http://www.rendezvouscottages.com.au/, which was incredibly pretty. It was especially nice to see so many birds flying around happily – not least because they were so well fed by the hosts at Rendezvous.

And now it is, as far as we can tell, “all gone”:http://www.abc.net.au/news/stories/2009/02/08/2485378.htm. There are a handful of buildings, at best, standing in the town of Marysville. On the main street (which I think doesn’t quite include Rendezvous, though the terminology is ambiguous) apparently the only building standing is, of all things, the bakery. At least 12 people, in a very small town, have died.

There’s very little we can do from a distance to help, but there are several ways to contribute financially to the immediate aid, and to reconstruction. The “Australian Red Cross”:http://www.abc.net.au/news/stories/2009/02/08/2485378.htm seems to be the primary donation source. But you might also want to support “Wildlife Victoria”:http://www.wildlifevictoria.org.au/cms/index.php?option=com_wrapper&view=wrapper&Itemid=43, which is looking after a lot of displaced and distressed animals. “John Quiggin”:http://johnquiggin.com/index.php/archives/2009/02/10/fire-disaster-appeal/ is running one of his many successful blog-based fundraising appeals, and you can donate through that if you want to help show how much blog readers help out in times of need.

Quick posts from around the web.

* Brian Leiter has a thread about “hot topics in metaphysics”:http://leiterreports.typepad.com/blog/2009/02/hot-topics-in-metaphysics.html. For a while there metaphysics seemed to be all mereology/meta-ontology, all the time, with a special focus on meta-ontological questions about mereology. I think (and hope) that’s not really a fair characterisation of what’s going on now, so head over to Leiter’s and tell us all what’s been happening.
* A new edition of _Nous_ is “now out”:http://www3.interscience.wiley.com/journal/117997227/home?CRETRY=1&SRETRY=0 featuring articles by Graham Oppy, Yuri Cath, and Jeremy Fantl and Matthew McGrath, among others.
* Terry Tao notes a “worrying research cut”:http://terrytao.wordpress.com/2009/02/06/proposed-stimulus-amendment-eliminates-14-billion-in-nsf-funding/ in a proposed amendment to the stimulus bill. I have no idea what’s happening throughout the stimulus debates, but it would be a worry if the horse trading cost us a lot of NSF funding.

A few snippets from around the webs.

• The speaker list for the “Arché metholodogy conference”:http://www.st-andrews.ac.uk/~armeth/2009/02/arche-methodology-conference-speakers/ has been posted, and it is a real all-star lineup. It looks like for the second year in a row, I’ll be arriving in St Andrews shortly after the best conference of the year.
• Rutgers now has an undergraduate philosophy journal.
• Jonathan Schaffer has posted some results of some “interesting experiments”:http://fleetwood.baylor.edu/certain_doubts/?p=908 about knowledge and contrasts.
• There is a new philosophy of science group blog, It’s Only a Theory

Here’s a simple question about game theory.

Imagine that you think (a) that coherent credences need not satisfy countable additivity, and you think (b) that sometimes mixed strategies are optimal, and so we should consider all mixed strategies in deciding what an agent should do. I’m not particularly fond of either (a) or (b), but I know that I have readers who endorse each, and I suspect that I have readers who endorse the conjunction of the two.

Now imagine we’re trying to analyse a game where a player has a countable infinity of option in front of them. Should we take one of the player’s options to be the mixed strategy where the player has, for each option, probability 0 of taking that option? If so, then (a) how do we evaluate how good a strategy that is, and (b) are there any cases where this is the optimal strategy?

Here’s a more particular instance of this puzzle. Row and Column are playing a game of infinite matching pennies. Each player has to select a positive integer. Row wins if they select the same number, Column wins if they select a different number. I imagine that the opponent of countable additivity will want to say that the solution to the game is that both players play the strategy of selecting a random number, with each number having probability zero of being selected. But I don’t know how the opponent of countable additivity figures out what the expected return of this strategy (or any other infinitary strategy) is for each player, so I don’t know why they would think it is an equilibrium. So what should someone who believes (a) and (b) say about this game?

I’m a bit late to the party on this one, but I wanted to note a very exciting service that David Bourget and David Chalmers have set up, “PhilPapers”:http://philpapers.org/. Here is how the site describes itself.

bq. PhilPapers is a comprehensive directory of online philosophy articles and books by academic philosophers. We monitor journals in many areas of philosophy, as well as archives and personal pages.

At first glance, the page seems to do everything I wanted an online philosophy archive and index to do. The only downside is that I have so much reading to do now!

What is it to forget that _p_? A simple analysis is that _S_ forgets that _p_ iff at one time _S_ knows that _p_, and at a later time, _S_ does not know that _p_. But this can’t be right, for the following four reasons.

If at t1, _S_ knows that _p_, and at t2, _S_ is dead, so knows nothing, _S_ has not forgotten that _p_.

At t1, George knows that he has hands. At t2, he reads the Meditations, and starts to doubt that he has hands. That is, he no longer believes he has hands. He doesn’t any more know that he has hands, but nor has he forgotten that he has hands.

At t1, John knows that the New Deal substantially lowered unemployment. At t2, John reads a newspaper column, in a usually reliable newspaper, saying that this was not true. With his new evidence, he now (quite reasonably) doubts that the New Deal substantially lowered unemployment. So he does not know this. But nor has he forgotten it.

At t1, Paul knows that his meeting is scheduled for 2pm. At t2, he gets an email (falsely) saying that the meeting has been moved to 3pm. Paul glances at the email, but doesn’t take in what it says. So he still believes that the meeting is at 2pm. Nevertheless, he doesn’t know this, for the email is a defeater for his knowledge. But nor has he forgotten the time of the meeting.

That seems to dispose of the simple theory fairly conclusively. But is there anything we can put in its place?

The call for papers for this year’s Bellingham Summer Philosophy Conference has just gone out, though I don’t believe there’s a link yet. But papers (of up to 25 pages) for consideration should be sent to Dennis Whitcomb (Dennis.Whitcomb-at-wwu-dot-edu) by March 1.

I’ve been thinking a bit about Sleeping Beauty, and I’ve found it a little easier to think about this variation on the original case. I was wondering whether anyone thinks this changes the case substantially.

On Sunday, Sleeping Beauty is told about the game setup, and a coin is tossed, but Beauty isn’t told the results.

On Monday, Beauty is woken iff the coin lands tails, is put back to sleep, and has her memory erased.

On Tuesday, Beauty is woken, stays awake for as long as she would have stayed awake for if she had been woken on Monday, then is put back to sleep.

On Wednesday, Beauty is woken, is told that it is Wednesday, and goes on with her life.

And the interesting question is, on each day, what should be her credence that the coin landed heads?

The primary change from the standard form of the story is to make the only day of waking if heads to be Tuesday, not Monday. This makes it somewhat easier to think about what Beauty should think on Wednesday. I also made it explicit that she doesn’t have her memory erased on Tuesday, and that she’s told on Wednesday that it is Wednesday.

The reason I’ve been thinking about this version of the case is that it makes it easier to see what Beauty should say on Wednesday. And the reason I was thinking about that is that I think it pulls apart two ways of thinking about the problem. (This is all inspired by Robert Stalnaker’s book _Our Knowledge of the Internal World_. But I don’t say that Stalnaker would endorse any of this.)

One way of thinking about the problem is in terms of centered worlds propositions. Beauty’s knowledge, at any moment, consists of the centered worlds that for all she knows are her centered world at that time. So on Tuesday, she can think the thought “This is Tuesday”, and this means that the centre is on Tuesday. And that’s a thought that is true on Tuesday and false on Wednesday.

Another way of thinking about the problem uses regular possible worlds propositions, but makes free use of demonstrative reference to times to ‘latch on’ to propositions about the time. So on Tuesday Beauty can think the thought “This₁ is Tuesday.” She might not know whether that is true, but she can consider the proposition. And she can think that thought on Wednesday, if she has sufficient memory to track that demonstrated time. And that proposition doesn’t change its truth value over time.

Now here’s one nice consequence of the latter way of thinking about the puzzle. Let’s say we want to say that on Tuesday, her credence in heads should be 1/3. (I’m not endorsing this, but a lot of people do. And I’m silent here about (a) what we should say about Monday, or for that matter Sunday, or (b) what the dynamic explanation is of how we get from Sunday to Monday to Tuesday.) And let’s also say, as I think we really must, that when she learns it is Wednesday, her credence in heads should be 1/2. What should be the explanation of the change from Tuesday to Wednesday?

On the regular propositions approach, all that happens is that Beauty conditionalises on her new information. On Tuesday she thinks the thought “This₁ is Tuesday.” She gives it credence 2/3, since she gives equal credence to each of the following possibilities.

• This₁ is Tuesday and the coin landed heads.
• This₁ is Tuesday and the coin landed tails.
• This₁ is Monday and the coin landed tails.

Then on Wednesday she learns that that₁ was Tuesday, so she can drop the third possibility. Conditionalising on the falsehood of that possibility gives her a new credence in heads of 1/2. That seems like an elegant solution to one part of the Sleeping Beauty problem.

Here’s an argument that every respectable epistemologist will reject the conclusion of. But I wonder which premise most people will think is false.

1. If S has a justified, true belief that _p_, then S is aware that _p_.
2. If S is aware that _p_, then S knows that _p_
3. So, if S has a justified, true belief that _p_, then S knows that _p_.

At a pinch, I’d say premise 2 is false. But I’d be interested to know which premise other people think is false.