Last week, I gave a talk in Manchester at a
(very nice) workshop on "David Lewis and His Place in the History of Analytic
Philosophy". My talk was on "Lewis's empiricism". I've now written it up as a
paper, since it got too long for a blog post.
The paper is really about hyperintensional epistemology. The question is how we
can make sense of the kind of metaphysical enquiry Lewis was engaged in if we
accept his models of knowledge and belief, which leave no room for substantive
investigations into non-contingent matters.
I wrote this short
piece for a special issue of the Journal of Consciousness Studies on
Chalmers's "The Meta-Problem
of Consciousness" (2018). Much of my paper rehashes ideas from section 5 of
Foundations" paper, but here I try to present these ideas more simply and
directly, without the Bayesian background.
The central claim I try to defend is that the hard problem of consciousness
arises from a particular method by which our brain processes sensory input.
Agents whose brain uses that method can be expected to be puzzled about
phenomenal consciousness, even if they live in a purely physical world.
The story is meant to answer the "meta-problem" of what gives rise to our
puzzlement about consciousness, but it is also meant to dissolve the first-order
problem: once we understand the source of the puzzlement, we should no longer
2018 paper, J. Dmitri Gallow shows that it is difficult to combine
multiple deference principles. The argument is a little complicated,
but the basic idea is surprisingly simple.
Suppose A and B are two weather forecasters. Let r be the
proposition that it will rain tomorrow, let A=x be the proposition
that A assigns probability x to r; similarly for B=x. Here are two
deference principles you might like to follow:
(1) Cr(r / A=x) = x.
(2) Cr(r / B=x) = x.
Now conceivably, A and B might issue different forecasts. So what
should you believe on the assumption that A=x and B=y, where x and y
are different? One natural idea is to split the difference:
Consider a world where eating doughnuts is illegal and where everyone
thinks it is OK to torture animals for fun. Suppose Norman at w is
eating doughnuts while torturing his pet kittens. Is he violating the
laws? Is he doing something immoral?
In one sense, yes, in another, no. His doughnut eating violates the
laws of w, but not the laws of our world. Conversely,
his kitten torturing violates a moral code accepted at our world, but
not a code accepted at w.
In general, when we ask whether people at other worlds do what they
ought to do, we can evaluate their actions relative to their
norms, or we can evaluate them relative to our norms. Both
perspectives make sense. But they lead to different deontic logics.
I recently refereed Eliezer Yudkowsky and Nate Soares's "Functional Decision
Theory" for a philosophy journal. My recommendation was to accept
resubmission with major revisions, but since the article had already
undergone a previous round of revisions and still had serious
problems, the editors (understandably) decided to reject it. I normally don't publish
my referee reports, but this time I'll make an exception because the
authors are well-known figures from outside academia, and I want to
explain why their account has a hard time gaining traction in academic
philosophy. I also want to explain why I think their account is wrong,
which is a separate point.
On the modal analysis of belief, 'S believes that p' is true iff p is
true at all possible worlds compatible with S's belief state. So
'believes' is a necessity modal. One might expect there to be a dual
possibility modal, a verb V such that 'S Vs that p' is true iff p is
true at some worlds compatible with S's belief state. But there
doesn't seem to be any such verb in English (or German). Why not?
What do we use if we want to say that something is compatible with
someone's beliefs? Suppose at some worlds compatible with Betty's
belief state, it is currently snowing. We could express this by "Betty
does not believe that it is not snowing". But (for some reason) that's
really hard to parse.
Gibbard's 1981 paper "Two recent theories of conditionals" contains
a famous passage about a poker game on a riverboat.
Sly Pete and Mr. Stone are playing poker on a Mississippi
riverboat. It is now up to Pete to call or fold. My henchman Zack sees
Stone's hand, which is quite good, and signals its content to Pete. My
henchman Jack sees both hands, and sees that Pete's hand is rather
low, so that Stone's is the winning hand. At this point, the room is
cleared. A few minutes later, Zack slips me a note which says "If Pete
called, he won," and Jack slips me a note which says "If Pete called,
he lost." I know that these notes both come from my trusted henchmen,
but do not know which of them sent which note. I conclude that Pete
One puzzle raised by this scenario is that it seems perfectly
appropriate for Zack and Jack to assert the relevant conditionals, and
neither Zack nor Jack has any false information. So it seems that the
conditionals should both be true. But then we'd have to deny that 'if
p then q' and 'if p then not-q' are contrary.
I've been reading about objective consequentialism lately. It's
interesting how pervasive and natural the use of counterfactuals is in
this context: what an agent ought to do, people say, is whichever
available act would lead to the best outcome (if it were
chosen). Nobody thinks that an agent ought to choose whichever act
will lead to the best outcome (if it is chosen). The
reason is clear: the indicative conditional is information-relative,
but the 'ought' of objective consequentialism is not supposed to be
information-relative. (That's the point of objective
consequentialism.) The 'ought' of objective consequentialism is
supposed to take into account all facts, known and unknown. But while
it makes perfect sense to ask what would happen under condition
C given the totality of facts @, even if @ does not imply C, it
arguably makes no sense to ask what will happen under condition
C given @, if @ does not imply C.
It has often been pointed out that the probability of an indicative
conditional 'if A then B' seems to equal the corresponding conditional
probability P(B/A). Similarly, the probability of a subjunctive
conditional 'if A were the case then B would be the case' seems to
equal the corresponding subjunctive conditional probability
P(B//A). Trying to come up with a semantics of conditionals that
validates these equalities proves tricky. Nonetheless, people keep
trying, buying into all sorts of crazy ideas to make the equalities
come out true.
I am puzzled about these efforts, for two reasons.
Dutch Book arguments are often used to justify various epistemic
norms – in particular, that credences should obey the
probability axioms and that they should evolve by
condionalization. Roughly speaking, the argument is that if someone
were to violate these norms, then they would be prepared to accept
bets which amount to a guaranteed loss, and that seems
But it's hard to spell out how exactly the argument is meant to go. In
fact, I'm not aware of any satisfactory statement. Here's my
For concreteness, I'll focus on the argument for probabilism,
but the case of conditionalization is similar.