Let us consider a possible world WM where consciousness is an M-property. At this world consciousness acts to collapse the wave function. Supposing that we live at WM can you or I have a zombie twin? A zombie twin is one that is physically identical to me in the relevant ways and which lacks consciousness. Suppose that I am actually suffering from a headache while eating Jelly Belly jelly beans. Then my zombie twin is in exactly the same physical states but without the consciousness. This means that the zombie must have a brain and that this brain must be in the same physical states that my brain is in. But my brain is in a collapsed state of definitely being in the relevant neural correlates (due to the presence of conscious experience). In the world where there is no consciousness, and which is physically just like WM (call this world WM-C), there would be no collapsed state. This is because the M property is missing. Since I am not in a superposition of states and my ‘zombie’ twin is we are not in the same physical states.
So it seems that if consciousness is an M-property then zombies are inconceivable and this in turns shows that if consciousness is an M-property then consciousness is a physical property.
But one might object that the right world to think about is WP. At this world the neural correlate of consciousness, construed here as distinct from consciousness itself (for the sake of argument), collapses the wave function. It is this world, continues the objection, rather than WM-C, that is the zombie world relative to WM. At WP there is a creature that has a brain, and which has a definite collapsed state identical to the neural correlates of the experience that I am actually having. This is the quantum zombie, not the one that is in the superposition of states.
I think it is is plausible that the creature at WP is in the same physical state as I am in some sense, but is it the case that WP has the same physics as WM? I would argue that they have similar physics but they are not the same. In WM when you lack consciousness you have a giant superposition that evolves deterministically according to the Schrodinger equation. There may be quasi-classical branches due to decoherence but that is not the same thing as there being a collapsed world, which is what we have at WP.
You cannot just start with WM and subtract consciousness and end up with WP. Instead you end up with WM-C and you then need to add some new physical law (or change the previous one), stating that it is the neural correlate that is responsible for collapsing the wave function. These worlds have different laws of physics and so are not the same. This is different than the zombie argument as normally construed, which leaves all the strictly physical laws in tact and simply posits the removal of the super-physical laws connecting the neural correlates of consciousness to actual consciousness.
Of course, consciousness probably isn’t an M-property but even so, any thoughts on the argument?
Richard Brown 
Interesting stuff. I’m super unfamiliar with the literature on this sorta stuff, so maybe I’m making an elementary blunder in what follows. But it seems to me that the argument in your first pgraph needs some re-wording to work. As worded, it leaves open that there might be other M-properties besides consciousness. If consciousness is only one of several M-properties, then your zombie doppleganger can be phenomenally vacant but fully collapsed due to some non-consciousness M-property being instantiated. If I’m on the right track here, then to fix the argument you need a premise that says something like “consciousness is the only M-property”. With that fix in place, the argument seems cool to me. But what do I know?
I think the argument is fine. It says that if consciousness is responsible for collapsing some wave functions, then a zombie world either does not have all the same collapses or it does not have them for all the same reasons. But there may be another objection: If collapsing wave functions is not a physical process, then something non-physical could play the same role as consciousness in the zombie world without changing the physics. More generally, we can say this: if consciousness is not epiphenomenal, then something must play the consciousness role in zombie worlds or else they are inconceivable.
*something non-physical must play the consciousness role in zombie worlds . . .
Er, on second thought, maybe Pete is making the same point as me, and just forgot to mention that the other M-property would have to be non-physical, too.
Well, I wouldn’t say I “forgot”– I thought it would be obvious that by stipulation the Zombie isn’t going to differ in any physical way. Anyway, I think we are on the same page.
hi richard — i just saw this and your previous post on m-properties. it’s a nice analysis (though it’s not quite true that i split my credence between panpsychism and interactionist dualism — i split it between russellian monism and substance dualism, where the former credence is split between panpsychism and panprotopsychism and the latter is split between epiphenomenalism and interactionism).
you’re right that a world where the NCC collapses the wavefunction isn’t quite a pure physical duplicate of a world where consciousness collapses the wavefunction, because it will have an extra physical law (though it’s arguably a microphysical duplicate with the same microphysical laws, as the extra NCC-collapse law isn’t really a microphysical law). at least that will be so on a nonhumean view of laws (what to say on a humean view where laws derive from regularities is tricky).
i think a pure physical duplicate of the consciousness-collapse world is still conceivable and possible, though. it will be a zombie world where every instance of the NCC happens to be followed by a collapse without a law connecting them. then that world will be physically just like our world — only the connection to consciousness will be different. it’s a weird world with causal gaps and unexplained events, but as far as i can tell it’s perfect conceivable. as i said in my response to perry some years ago (at http://consc.net/papers/perry.html):
“An interactionist dualist can accept the possibility of zombies, by accepting the possibility of physically identical worlds in which physical causal gaps (those filled in the actual world by mental processes) go unfilled, or are filled by something other than mental processes. The first possibility would have many unexplained physical events, but there is nothing metaphysically impossible about unexplained physical events.”
p.s. pete and jason are right that there could also be worlds with nonphysical and nonphenomenal m-properties collapsing the wavefunction. that would correspond to the second possibility in the quote from my perry response above, on which physical causal gaps are filled by something other than mental processes.
How do you mean “there is nothing metaphysically impossible about unexplained physical events”? Do you have an example? Maybe you have a different definition of metaphysical
The posit of the neural correlates of consciousness is perfectly appropriate and comprehensible, but the “actual consciousness” part is complexing because I’d propose (as a mere bystander) that, stemming from neuroscientist’s concept of consciousness, “actual consciousness” shouldn’t exist. Is that “actual consciousness collapses neural correlates of consciousness” saying that it is the actual consciousness putting the correlative consciousness on balance? If so, ’twas a good point which would entail that one could be completely conscious or rational as i’d put it. So then abandoning correlates of consciousness opposed to “real” consciousness would be tantamount to claiming to be human with no body? I conclude unconscious being unable to establish a connection between mind and body, correlatively conscious being having brain activity ominous to consciousness (action), and then really conscious having the ability and performing. Fourth of all, ultimate reality having the potential of all three but upholds its potential and uniqueness in more esteem than interfering in such contexts of consciousness. Possibly. Nevertheless, I can’t see the difference between a human and zombie, so the inferential analogy is on point but frivolous. I hold there’s a different consciousness for many breeds of humans, zombie being one breed and consciousness. But, after all I’m ultimately a zombie per se.
Hello Professor Chalmers.
“you’re right that a world where the NCC collapses the wavefunction isn’t quite a pure physical duplicate of a world where consciousness collapses the wavefunction”
Not unless consciousness can be reductively explained in terms of the NCC. That is to say, if it turns out that the “stuff” of phenomenal consciousness is logically supervenient on the NCC, then NCC collapsing the wavefunction and consciousness collapsing it will turn out to be the same thing (from the concepts alone). In that case, consciousness will be a free lunch wherever and whenever the NCC is instantiated.
I disagree with Searle’s view that something causally reducible is not ontologically reducible. I agree that there is a conceptual difference between the first and third-person, and obviously we recognise a distinction that seems to go beyond mere concepts from our own case… But… Even if I acknowledge the ontological gap between the first and third-person, I will only concede that it is due to our lack of knowledge of ontological categories. If we knew more about the intrinsic nature of the physical for example, this “causal reduction” would reduce to “ontological reduction”, in fact, I believe this is true for all causal chains. Brute causation is too mysterious! Russell touches on physics as providing extrinsic/relational properties and not intrinsic properites. This is where I think the value in your theory definitely shines through, Prof.
“nonphenomenal m-properties collapsing the wavefunction”
Nonphenomenal m-properties is just another way of referring to functional and/or behavioral, psychological properties, such as awareness for example.
With regards to “nonphenomenal m-properties”, intentionality seems to be a tricky one. Nevertheless, it seems that being able to represent “aboutness” of mental properties is itself qualitative. Qualia seem to be a subset of intentionality in that they are about what they are like. What qualia are like is that they stand out from each other – relationally – as contrasting pieces of information viewed from the inside. This is also what they are “about” (intentionally speaking).
As a physicalist, I take the hard problem seriously. I have a theory of qualia in functional terms which proposes a solution to the inverted spectrum argument. I argue that there is no redness-in-itself beyond the ability to contrast it with that which is non-red. The thought that we can swap red with another colour without affecting how they all relate to each other, is a side-effect or illusory byproduct of the ability to discriminate properties of visual content in the first place. Just as a blind person has no idea of colours, they have no idea of darkness either, yet we never recognise this. Does Mary knows she is seeing black and white? I have said much more about my solution to the hard problem on my YouTube Channel.
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