Wolfgang Schwarz

Homecoming

I'm back in Germany. Nice and rainy here. Blogging will also resume at some point or other.

Content, form, and hyperintensions

I'm off to the Blue Mountains for a week. In lieu of philosophical content, here is a rant on semantic contents and hyperintensions that I wrote last year.

When philosophers talk about meanings (or contents, or semantic values), they rarely explain what these things are meant to do -- what constraints an adequate theory of meaning would have to meet. Trying to figure out those constraints from what is implicitly used in discussions and arguments, one gets a laundry list of miscellaneous features with hardly any theoretical unity. Meanings are supposed to determine (together with syntactic structure) the truth-value of sentences; they are supposed to be known by competent speakers; they are supposed to be conventionally associated with symbols and sounds; they are supposed to track what a sentence is (intuitively) about, and also in which possible worlds it is (intuitively?) true; they are supposed to be part of a model of how our brain processes and generates words; they are supposed to be possible objects of beliefs and desires; they are supposed to play various roles in speech act theory; they are supposed to the referents of 'that' clauses; they are supposed be such that one can truly utter 'Fred said that P' if and sonly if Fred uttered a sentence whose meaning is the same as the meaning of 'P'. And so on and on.

philpapers

The "something even bigger" that I mentioned when I made the online papers feed public has finally arrived: philpapers.org.

News

Sometime later this year I will move to Cologne (Germany) as part of a recently approved Emmy Noether project on apriority and understanding. The other parts of the project so far are Brendan Balcerak Jackson and Magdalena Balcerak Jackson, but we're looking for PhD students. If you might be interested, here are the details.

Unrelatedly, I made some changes to the blog. Let me know if anything's broken.

Lewis book

I forgot to mention that my book on Lewis has been released a couple of weeks ago. It's a distant descendant of my PhD thesis, and in German.

Values and consequences in economics and quantum mechanics

One of the novelties in Richard Jeffrey's "Logic of Decision" (1965) was to unify the space over which probabilities and values are defined: both probability and desirability are distributed over the space of possible worlds, of ways things might be. By contrast, in earlier theories like that of Savage, probabilities were defined over states (or events) and utilities over consequences, which were taken to be distinct kinds of things. Technically, this difference between Savage and Jeffrey isn't terribly important as long as anything an agent may care about can be found in the set of 'consequences'. However, the distinction and the labeling in Savage's treatment carries a danger to overlook the complexity of human values. This has, I believe, led to a number of serious mistakes.

Chance, credence, and centers

Rational credence should match the expectation of objective chance. Here I will have a brief look at what happens to this connection between credence and chance on the assumption that credence is centered and chance is not.

1. Fixing the time. Both credences and chances evolve over time. When a coin is tossed twice, the chance of two heads may initially be 1/4; after the first toss has come up heads, it is 1/2. So when your beliefs should match the assumed chance, it can only match the chance you assume to obtain at some particular time. At what time?

Can evidence be inadmissible?

First, a quick reminder of history. David Lewis once proposed a principle (the 'Principal Principle') linking rational credence and objective chance. It says (or rather, entails) that your rational credence in any proposition A, on the assumption that the objective chance of A is x, should also be x, no matter what (further) evidence E you have:

OP: P(A | ch(A)=x & E) = x.

This principle, the 'Old Principle', is widely taken to suffer from two defects. First, suppose your evidence E includes ~A. Then probability theory ensures that P(A | ch(A)=x & E) = 0, irrespective of x. Lewis responded by restricting OP to cases where E is 'admissible'. He suggested that a (true) proposition is admissible iff it is entailed by the history of the world up to now together with the laws of nature.

Are cartoon characters persons?

A judge in the New South Wales Supreme Court has decided that Bart and Lisa Simpson are persons under the age of 16.

This is odd. According to The Simpsons, Bart and Lisa are certainly persons under the age of 16; but 'according to The Simpsons, P' does not entail P, I would have thought. Indeed, according to the Simpsons, Bart and Lisa exist, while in reality they don't. And since Bart doesn't exist, no-one is Bart Simpson; so in particular, every person under the age of 16 is not Bart Simpson; therefore Bart Simpson is not a person under the age of 16.

Mike Titelbaum on Shifting and Sleeping Beauty

In the last entry, I have suggested that

EEP) P_2(A) = P_1(+A|+E)

is a sensible rule for updating self-locating beliefs. Here, E is the total evidence received at time 2 (the time of P_2), and '+' denotes a function that shifts the evaluation index of propositions, much like 'in 5 minutes': '+A' is true at a centered world w iff A is true at the next point from w where new information is received. (EEP) therefore says that upon learning E, your new credence in any proposition A should equal your previous conditional credence that A will obtain at the next point when information comes in, given that this information is E.