I had planned on posting here more once back from Taiwan but that has’t exactly worked out! If one wants to see the videos from the conference in Taiwan they are here and I will eventually write up a paper from my talk (and the one I gave at the Grad Center). Even so lots has been going on. I am also happy to announce that I am now officially Tenured and promoted to Full Professor! Tenured Full Professor…It hasn’t quite sunk in yet but it is still pretty cool.

In other news I am getting ready to head up to UConn to give a talk. I left UConn way back in 2003 to come to NYC and I went back in 2007 to participate in the Yale/UCONN graduate conference but I haven’t been back since then so I am looking forward to it! I figure since it is so close to Halloween I will talk about ways to kill zombies. In particular I have been thinking a lot about the 2D argument against dualism and plan to present an updated version of that. I have a draft up at PhilPaper which I wrote after my presentation at the Towards a Science of Consciousness conference back in 2012 and the helpful comments from Dave on the linked to post but I think I have a better way to present it now.

The main points are the same: The shombie argument is aimed at establishing the falsity of dualism, not the truth of physicalism. Physicalism can be formulated as the familiar [](P ⊃ Q) and dualism can be formulated as the claim that it is necessary that if all there is in a world is the physics of our world then there is no consciousness at that world. We can symbolize that as [](PT ⊃ ~Q). Here PT is the conjunction of the familiar P (a complete description of the fundamental microphysics of our world, laws and particles, etc) together with a ‘that’s all’ clause. To show that this is false we need to show that it is possible that we could have PT and at the same time Q. In symbols ◊(PT & Q). So the shombie argument is as follows. PT & Q is conceivable and so possible. From that it follows that [](PT ⊃ ~Q) is false. From here the main action is how to understand the that’s all clause. Dave suggested a modal and non-modal (see the paper or his comments) way to interpret it and I think either of those would work. There are tricky issues about parity here and whatever turns out to be the case for shombies should be the case for the zombie argument as well. So if we need to invoke modal notions, or notions of fundamentality to describe the shombie world then I am happy with that as long as we also need to do it to describe zombie worlds.

However that turns out I think we can describe the shombie world without any modal terms in any of the premises. I understand the shombie world to roughly be the following kind of world. For everything that exists in that world there is a physical property which is that thing. We can symbolize this as: (x)[∃y(y=x) ⊃ ∃z(Pz & (z=x))]. This says that for anything that exists there is some physical property which is that thing. Here one might object that the identity statement in the consequent already has modal notions smuggled in but I think we can get rid of this as well. The basic idea is that we have a non-modal way of understanding what it means to say that x is identical to y, it just means that if x has some property F then so does y. In symbols this is (x=y) ⊃ (Fx ⊃ Fy). We can substitute this into the above to get (x)[∃y(y=x) ⊃ ∃z(Pz & (Fz ⊃ Fx))] which is now a non-modal ‘that’s all’ clause. It says that for any object which exists there is some physical property (which may be very complex) such that if that property is a certain way then so is the physical object. It may be the case that I need something like ‘for all F, if z is F then x is F’ or maybe even ‘for all F, z is F if and only if Fx’ but either way there are no modal claims here. We simply imagine one world where consciousness is physical and that is enough to show that dualism is false. We do not need to imagine anything complicated like that it is possible that it is necessary that P entails Q.

In the course of re-working all of this it struck me that I spend a lot of time trying to show that the zombie argument (and related scenarios like inversions etc) are not relevant to the question of physicalism. Thus I think that in the shombie case if one is partial to modal rationalism (as I sometimes am) then only one of the pair (zombies, shombies) can be ideally conceivable and different people find them differently conceivable. Thus for us these intuitions are not helpful one way or the other. This was also the point I was trying to make in my short paper Zombies and Simulation which was in the JCS issue on Dave’s singularity paper. But another route to this kind of conclusion just struck me.

Suppose that the identity theory is true, so that consciousness in our world is (necessarily) physical, let us symbolize that as b=q, where b is some brain state and q is some episode of consciousness. If the identity theory is true are zombies conceivable (and you accept modal rationalism)? The answer seems to be ‘no’. For, suppose that b=q as we have said. Then someone who said that you could have a physical duplicate of me, which includes b, and yet lack consciousness, q, would be asserting both that b was and was not instantiated at the possible world in question. It is instantiated because I am described as being in brain state b and yet it is described as not being there because we are told that there is no q, even though we are assuming that b=q. This is like being told that there is H2O (and our laws of physics) and yet no water. If water is H2O then this is not conceivable.

So far so good, but what is often unnoticed is that we can conceive of a creature that is physically just like me except that it is not in brain state b (and so not having conscious experience q). It seems like there is nothing contradictory about the scenario where this creature behaves just like I do when I have the relevant brain state (and thus the relevant conscious experience). This will be a world where there are causal gaps, where, that is, the behavior of our world is duplicated but without the usual causes. So this creature may put its hand in the fire and in me this would cause brain state b (and thus conscious experience q) and this in turn would case me to yell etc. But the creature we are imagining puts its hand in the fire and does not go into the relevant brain state, but does go into the relevant states that cause behavior (and has the relevant beliefs, etc). This creature still has a brain and is very similar to me excepting for the fact that it has no conscious experience (due to lacking those specific brain states) and all of these strange causal gaps (to make its behavior indistinguishable from mine). This creature counts as a zombie, though not the kind that is relevant to physicalism. Thus one kind of zombie threatens the identity theory while the other does not. So which one is really conceivable? I find that I can only really make sense of the non-threatening kind (surprise! surprise!)But what kind of evidence could push us one way or the other? Once again I find conceivability (for now) to be of now use in answering questions about consciousness.

Ok enough for now! I am hoping to make it out to what should be a very interesting discussion of a paper by Jonathan Simon on how to conceive of pain inversions (I hope someday to write up some of the stuff that comes out of the nyu consciousness discussion group but we’ll have to see if Ryland lets me! 🙂