I've thought a bit about counterpart-theoretic semantics last year, both for natural language and for quantified modal logic. Here's a paper in which I present my preferred version of this framework as applied to natural language: Counterpart Theory and the Paradox of Occasional Identity. Apart from the semantics itself, my main claim is that the advantages of counterpart semantics do not require the metaphysics of "counterpart theory".
Here is another paper which covers related grounds, but from a more logical point of view: How Things are Elsewhere: Adventures in Counterpart Semantics. Comments on either paper are very welcome.
I've just replaced the Online Papers in Philosophy Feed by a newer version. Let me know if you run into any problems with that. (You may also consider switching to a feed from PhilPapers.)
Have I mentioned that the source code for the scripts that generate the feed is on github? Well, now I have.
(While I'm in the swing of mentioning, I might as well also mention (i) that my paper on updating self-locating beliefs is forthcoming in Phil Studies, (ii) that I won't be at the AAP this year, although I will be at various other events, like here, here and there, and (iii) that Holly and I are not "in a relationship" any more. In case you wondered about any of these.)
To some extent, one can account for semantic phenomena without
assigning meanings to words or sentences or thoughts. For instance, we
might say that beliefs and other attitudes are relations to
sentences, i.e. to strings of symbols. Roughly, to believe a
sentence S is to be disposed to utter (or assent to) S (or some
translation of S) under certain conditions. When people talk to each
other, such dispositions may be transferred: after hearing
me utter the sounds "it is raining", you acquire the disposition to
utter those sounds yourself. Apart from communication, we can also
account for things like synonymy and analyticity. Roughly, two sentences
are synonymous if necessarily, anyone who stands in the belief
relation to one of them also stands in the belief relation to the
other. There is no compositional semantics in this picture, because
there is no semantics at all. But there might be recursive rules for
translating from one language to another.
A lot has been written in the last 10 years or so on updating
self-locating beliefs, mostly in the context of the Sleeping Beauty
problem. One thing almost all of these papers have in common is that
they quote Lewis's remark in "Attitudes de dicto and de se" (1979,
p.534), where he says:
it is interesting to ask what happens to decision theory
if we take all attitudes as de se. Answer: very little. We replace the
space of worlds by the space of centered worlds, or by the space of
all inhabitants of worlds. All else is just as before.
This is supposed to imply that Lewis took standard
conditionalisation to be the correct update rule for self-locating
belief.
Professor Procrastinate has to make an important phone call. The
call is long overdue because Procrastinate has been playing Farmville
all week. The problem is that Procrastinate values current pleasure
higher than future pleasure. So when he applies his decision theory,
he finds that it is better to play some more Farmville now and make
the phone call later instead of making the call now: it doesn't matter much
whether the call is delayed by a few more hours, and this way the
immediate future will be much more pleasant.
There has been some discussion recently about whether propositions
are true or false absolutely, or only relative to a possible world, or
relative to a world and a time. What hasn't been considered, to my
knowledge, is whether propositions are true or false only relative to
a branch of the wave function of the universe.
For example, suppose we shoot a photon at a half-silvered
mirror. It then enters into a superposition of passing through
and getting reflected: these are the two "branches" of the
superposition. More precisely, it is not the photon that enters into
the superposition, but the entire setup, and there are actually many
more branches, corresponding to various precise paths the photon can
take. Moreover, these branches are only the position branches
of the superposition -- there are other branches of the same
superposition, corresponding to resolutions of other properties.
In metaphysics, "Humeans" are people who believe that truths
about laws of nature, counterfactuals, dispositions and the like
(truths about what must or would be the case) are in
some sense reducible to non-modal truths (about what is the
case).
One way to be a Humean is to deny that there are any laws
of natures, non-trivial counterfactuals, etc.: if there are no modal
truths, then trivially all modal truths are reducible to non-modal
truths. On this account, there are no "necessary connections between
distinct existences": eating arsenic might in fact be followed by
death, but it could just as well be followed by hiccups or anything
else.
This paper (recently
featured on the
physics arXiv blog) argues that if the universe never comes to an
end, then the universe will probably come to an end within the next 5 billion
years. The reasoning, as far as I can tell, goes roughly like
this.
First, define the probability of an event of type A given an event
of type B as the total number of A events over the number of B
events. If the universe is infinite, then the total number of A events
and B events will often be infinite. But infinity over infinity isn't
well-defined. So to have well-defined probabilities, the relevant
counts of A and B events must be restricted, e.g. to a finite initial
segment of the universe.
OK. We're back in Canberra. I've also finished the completeness proof
that I've been working on for the last few months. More on that soon. In the
meantime, here are some pictures from this year's bike
trip through the Alps.
.
Suppose you add to the language of first-order logic a sentence operator L for which you stipulate that all instances of
(L(p -> q) & Lp) -> Lq
are valid and that validity is closed under prefixing L's:
if p is valid, then so is Lp.
For example, L could be the modal operator 'necessarily', or it could
mean the same as '![$m[1]](/texer/images/?format=gif&fontsize=12pt&tex=%5Cforall+x)
'. If it means the same as
'', then