In response to Philip Goff at the OCC David Chalmers has argued that his 2D argument against physicalism is not committed to what Goff called Phenomenal Transparency. PT, to a first approximation, is the claim the having a phenomenal concept allows one to know the true nature of the concept. Opaque concepts do not. Consider the concept of WATER. You can have full mastery of that concept and yet not know that water is H2O. This was the state of everyone prior to the discovery that water was H2O. I have argued that if we take the spirit of the identity theory and transpose it into the 2D framework we get a view that is immune to the zombie argument as this translates into the claim that the primary and secondary intensions for phenomenal concepts come apart. Dave now says that the zombie argument should none the less go through on such a view. It doesn’t depend on phenomenal transparency just like conceiving of Twin Earth doesn’t depend on chemical transparency. In the Two-Dimensional Argument Against Materialism Dace says,
…it is worth noting that (contrary to a common supposition), the assumption that Q has the same primary and secondary intensions is not necessary for the [zombie argument] to go through. To see this, we can consider the version of the argument where we adjoin a “that’s-all” clause to P. From (1) (1) [P&~Q is conceivable] and (2) [If P&~Q is conceivable, then P&~Q is 1-possible], we can derive the conclusion that there is a minimal world verifying P in which the primary intension of Q is false. If P has the same primary and secondary intensions, then this world will be a minimal P-world in which the primary intension of Q is false. This world must differ from our world, because the primary intension of Q is true in our world…It follows that there is a minimal P-world that is not a duplicate of our world, so that physicalism is false of our world. It could be that strictly speaking physicalism will be true of consciousness, because P necessitates Q, but physicalism will be false of properties closely associated with consciousness, namely those associated with the primary intension of Q. We might think of this sort of view as one on which phenomenal properties are physical properties that have non-physical properties as modes of presentation.
But the claim here should be that transparency is required in order for (1) to be true. Consider the case of water and H2O. Since WATER is opaque may have seemed to Aristotle that he could conceive of a world where there was H2O but no water. He might have thought he could conceive of this because WATER is opaque. We cannot tell by either looking at water casually or examining our concept WATER that it is H2O. When a concept is opaque in this way we can conceive of worlds where the primary intension picks out something other than what it does here but we are not licensed to conceive of worlds where the secondary intension isn’t there unless we are in a position to say what the secondary intension of the concept is. Otherwise we would have to admit that Aristotle could conceive of a world physically just like ours without water! So the zombie argument does depend on transparency not as a way to get (2) as Philip suggested but as a way to get (1).
Richard Brown 
hi, my name is marlon, I had you las a teacher previously and I had a question regarding free will and the multiverse. I’m something of an amateur physicist and recently I’ve been giving some thought to the multiverse theory, the idea that infinite worlds exist where all things are simultaneously possible, so in these parallel worlds where we make one choice there is another world where we made another choice. This goes on ad infinitum until no matter what the choice, somewhere I made it (just to use me as an example). If this multiverse theory is true then all these universes exist, and the way physicists seem to present their idea is that we would choose a different outcome and it is this choice that would actually create the parallel worlds. My problem here is that if the universe where we make the choice exists because we made the choice. So to exist within any particular universe wouldnt that mean that we had to make that choice? So our lives are predetermined based on our existence in this universe?
Of course if the multiverse theory is incorrect my arguments against free will not apply. But I want to know if my reasoning on free will is sound. I’m sure you’re busy but if you have time you can look into the multiverse theories, in case my explanation was too convoluted. Sorry for hijacking your blog but I figured you might have an interesting take on this
Hi Dr Brown,
I’m absolutely with you on this, however I have decided to approach it in a slightly different manner.
I think Chalmer’s is right in arguing that Q does not need to be semantically neutral for the zombie argument to go through. If P&~Q is 1-possible physicalism about consciousness is false. But this stems from restricting the set of worlds to P worlds. If physicalism is true of P – if the physical stuff of P is sufficient* for Q – then it is true of all P worlds – irrespective of whether they are being considered as actual or as counterfactual. Likewise if physicalism is false of P it is necessarily false of P. There is no consistent set of worlds where the truth of physicalism about P is contingent.
As such, when we perform a 2-d analysis of P&~Q we should really be drawing 2 matrices: one in which physicalism is true of P and P&~Q has a necessarily false primary and secondary intension, and one in which physicalism is false of P in which case P&~Q has a necessarily false 2-intension (since we know Q to be true of this world) and a contingent 1-intension.
In other words, since we do not know whether Q extends to a physical state or to some non-physical ‘spooky state’ we cannot say whether or not P&~Q will be ideally 1-conceivable.
It seems to me that a lot of the conviction that zombies are ideally 1-conceivable stems from people conceiving about inconsistent sets of possible worlds. By thinking that since P&~Q is true when a world in which physicalism is false (and no one is conscious) is considered as actual P&~Q must be ideally 1-conceivable. However, since if physicalism turns out to be true of P, it will be necessarily true of P, there will be no consistent P world in which physicalism is false to be considered as actual.
The crux of the argument is that claiming P&~Q is ideally 1-conceivable presupposes the falsity of physicalism (or Russellean monism) (or the falsity of the CP thesis)
Perhaps that’s not especially clear, but I would be very interested in your thoughts on the matter.
*sufficient for Q, as opposed to necessitates Q, because it seems to me that anti-zombies or (reverse zombies as you call them) only require that we can deduce from the physical facts “that X is conscious” not that we can deduce “what that consciousness is like”
actually, to clarify on *
* when Q is a specific ‘what its like’ phenomenal truth such as ‘S is in pain’.
[…] The Zombie Argument Depends on Phenomenal Transparency […]
This is a very interesting point, and I wonder if Prof Brown discusses it further elsewhere! I’d really like to follow it better than I probably do.
Here’s my reaction/beware a nonspecialist/nonphilosopher who is confused and trying to find bearings! My sense is the analogy here is P~H2O, Q~water, and the idea is to challenge you can conceive of P without Q, if Q’s primary/secondary intensions come apart, on the analogy you can’t conceive of H2O without water (where water, analogous to an opaque version of Q, has differing primary/secondary intensions: clear/drinkable/watery/liquidy and the chemical structure H2O respectively).
I’ve tried thinking for a bit about this but might not yet be following the argument, because there are two possible senses in which you might challenge conceivability of P without Q based on the water / H2O analogy based on my reading of the blog post, with the first apparently not what Prof Brown is getting at, but the second seems answered in the passage of Prof Chalmers in a way that I feel he might not disagree with Prof Brown??
First, you might challenge the primary conceivability of P without Q itself. Now, this I’d think comes down to one’s sense about Prof Chalmers’ intuition about structure/dynamics not accounting for the ‘what it’s like’ stuff, and doesn’t turn on whether the primary/secondary intensions come apart for Q–indeed, one might as well say that even if Q has the same primary/secondary intension, you can’t conceive of P without Q in the sense that structure/dynamics DOES account for the primary intension of Q (I’d think this is at least controversial/and why there’s any force to the zombie argument, even if one doesn’t accept it ultimately).
I’d think Chalmers may agree that Aristotle can’t even primarily conceive (in the ideal rational sense, not a weaker sense) of H2O without water, at least in context of this passage, in that, if H2O really is transparent as he’s assuming P is in this passage, you can work out (even if that takes lots of hard, non-obvious work) that it refers to a watery/drinkable/liquidy thing. Just that this is precisely where, on structure/dynamics considerations, it seems harder to say the same about the P/Q case.
And he’d certainly seem to agree you can’t ideally imagine the secondary=primary intension of H2O doesn’t account for the secondary intension of water, since the latter is out of reach to our a priori reasoning anyway.
This would seem to correspond to his point that P may account for the secondary intension of Q, but not its ‘mode of presentation.’ I.e. consciousness may be physical, but not its mode of presentation: “It could be that strictly speaking physicalism will be true of consciousness, because P necessitates Q, but physicalism will be false of properties closely associated with consciousness, namely those associated with the primary intension of Q.”
In other words, the opacity of Q does mean that, as terribly surprising as it may be, consciousness really is a brain state, but the primary intension remains unaccounted for — precisely because Chalmers is assuming in this passage that P has the same primary/secondary intension, and so in this case, the structure/dynamics considerations feeding the zombie argument have an anti-physicalist conclusion.
The alternative is of course discussed shortly below, where the primary intension/secondary intension of P come apart, and here Chalmers is open to more nonstandard versions of physicalism, where the structure/dynamics considerations don’t destroy physicalism, only some more orthodox versions of it.
I think there’s one case left out, where Q is what you’d call *totally* opaque, where there is nothing you could call a primary intension of Q, but I think this seems to not be allowed by Chalmers’ framework (albeit, there are philosophers like Prof Goff who wrote they don’t want to rule out ‘radically opaque’ concepts).
I wonder what I’m missing! I realize it’s an old blog post, but it got me thinking.