UPDATE: It turns out that I am an insensitive jerk and that my commentator was Anton AlTerman not AlDerman…sorry about that!!

I am working my way through the comments on my paper for tomorrow and thought it would be helpful to make some quick responses. First I would like to thank Anton for his comments; they are almost as long as my paper itself!!

A main contention of my paper is that zombies are not conceivable, or at least that it is not obvious that they are. Alterman takes issue with this claim and offers the following in support of the claim that he can imagine zombies;

…let me try to respond with a defense of the zombie imaginer before we move on to Brown’s main argument. My “evidence” will consist in conceptual support for the point that conceiving of a zombie requires nothing more than adding and subtracting properties, something any normal person can do. So first, I can imagine someone physically identical to myself who is in the same room but is not aware of the slightly bluish tint of the late afternoon light, or the background humming of the air conditioning, while I am aware of all that. For I can imagine myself not having been aware of any them, and yet being physically identical to my actual self; just as when I see the duck and then see the rabbit in the same drawing, I have no reason to believe that a microphysical change took place, and even less reason to think that a determinate, repeatable microphysical change took place. Similar arguments could be brought for memory, imagination, and other components of consciousness. Therefore I can imagine a being that is physically identical to myself but lacks consciousness.

There are several problems with this attempt to offer ‘evidence’ for the conceivability of zombies. First, there is am equivocation on ‘physically identical’. It is true in one sense that I can imagine myself not being aware of the blueish tint in the room. I may not be looking at it, I may have my eyes closed, there may be bad light, etc, etc. In this case there is a sense in which I am imagining something that is identical to me, but I am clearly not imagining myself as being in the very same brain states, so I am clearly not imagining a physical duplicate of myself who is unaware of the blue tint in the relevant sense. What we need is to imagine me being in the very same brain state and not being conscious of the blueish tint. This is exactly what is in question –that is, whether this is something that can be imagined– and so this is at best question begging.

Alterman goes one to cite, as evidence, his convixtion that he has no reason tot hink that there is a microphysical change in his brain when he is looking at an ambiguous stimulus (like the duck-rabbit, or the Necker cube), but this is rather naive. There is evidence in both Humans and primates that there are changes in brain activation that correlate to the change in perception in these kinds of cases. You see it one way we get one kind of activation, you see it the other you get another kind of activation. So I am a bit mystified as to why Alterman see no reason to think there is a physical difference between the two cases and this line of evidence fails to establish the conceivability of zombies.

He goes on to offer a second line of ‘evidence’ saying,

Second, we can arrive at the concept of a zombie by expanding on concepts like blindsight or sleepwalking. These documented empirical states involve acting and behaving in certain situations like a normal human being but completely lacking awareness of one’s behavior or surroundings. A being who is always in such states would be a zombie.

This is even worse than his first line of ‘evidence’. The ‘documented empirical cases’ he points to are ones which obviously include a physical difference. So in the case of the sleepwalker their brain is in a very different chemical state than the person who is awake and on the blindsight cases these patients have their V1 visual cortex missing! Quite a physical difference, not to mention the point made by Block oh so long ago to the effect that blindsight is not automatically evidence for a lack of qualitative consciousness as opposed to a lack of access. Either way these kinds of cases offer no support for those that claim to be able to imagine zombies.

Alterman then goesn on to address my Kripkean argument from a posterori identies. He say,

The logic of Brown’s argument is that dualists cannot force the issue against materialism by stating a priori that zombies are conceivable, since it may turn out a posteriori that the connection between brains and consciousness is a necessary one…The form of the objection seems wrong, because we cannot say in advance that discovering a physical basis for consciousness will make zombies inconceivable. Consciousness could be more like the terms “evolution” or “radiation” than like “water” or “heat”. The former are natural kind terms, but neither has an essence that can be expressed in an identity statement.

To be frank I find this very confusing. Why is it that evolution and radiation don’t have ‘essences which can be expressed in an indentity statement’? They seem clearly to have such essences to me, but maybe I am missing something. Either way I don’t see how this is supposed to affect my point. If physicalism is true then every mental state is a brain state; what clearer case of a candidate for a posterori identity is there?

Alterman goes on to say,

I fail to see any reason why thought experiments should be constrained by the combined demands of a controversial theory of reference for natural kind terms and the empirical possibility that reductionist programs will be successful.

This is quite a bizarre claim. The point I was making was that the zombie argument begs the question against a certain type of physicalism, namely one that takes a Kripkean line about reference. There is good reason to take such a theory seriously whether or not one finds it ‘controversial’ . I don’t; I find it to be true and non-controversial, but so what? The point is that it is a contender and so one ought not to steam role over it. As for the second point, this is even more bizare, at least given what I argue oin the paper. I am not really interested in whether consciousness is reducible or not. As I argue, this is an explanatory notion not an ontological one. Maybe Anomolous Monism is the correct physicalist theory –who knows? Stranger things have happened– if it is then mental concept terms cannot be reduced to physical one but that doesn’t mean that all tere is is the brain and its states. The point is that for all we know physicalism is true and if it is then zombies are inconceivable; Alterman hasn’t said anything that mitigates against this claim.

Alterman goes on to make this stunning claim,

Take our current, fairly sophisticated understanding of color vision; how does it even come close to explaining why red objects appear red and not green? No physicalist story even gets off the ground on this kind of question. The same holds for consciousness in general: in spite of having mapped and experimented with dozens of brain areas, having sophisticated biochemical analyses of brain activity, and even manipulating some basic motor functions with digitally simulated brain signals, we don’t have so much as a program for explaining conscious experience, or even the function of consciousness, as an outcome of any of this biophysical research.

It may be the case that we don’t have a neurological account of this (though some would beg to differ) but that doesn’t show that we don’t have a philosophical theory of how this happens. One such theory if the Higher-Order Theory of Consciousness which, whether it is true or not, does quite a nice job at explaining why red objects apear red and not green. They do so because we are conscious of ourselves as seeing red not green. You may not like this answer but it certainly does what Alterman says we we don’t have a clue about doing.

Alterman then says “A second point Brown makes is that conceivability does not entail possibility.” No, this is not a point that I make. I make the point that some people make this point. I am happy to admit that conceivability entails possibility but that is because I think that actuality entails conceivability and of course actuality entails possibility. I don’t know why he accuses me of denying this. But I don’t and so none of what follows applies to me. 

Alterman then turns to addressing the zoombie and shombie arguments directly. Of the zoombie argument he says,

I agree that the zombie argument is not a conclusive argument against physicalism; but what it purports to show, at least, is that we are not forced to choose between a materialist theory of consciousness and a spooky view of the universe. If we can conceptually dissociate consciousness from the particular forms in which it is embodied, we can imagine a universe in which it is realized in other ways; and if we can do that, we can give up the idea that there must be a reductive, biophysical explanation of consciousness. I fail to see what parallel objective is achieved by positing “zoombies”, since no one is claiming that there is a necessary link between our “non-physical” qualities and consciousness.

This last bit would be suprising to David Chalmers who is claiming that there is a necessary link between our non-physical qualities and consciousness. This is precisely why Chalmers thinks that the zombie argument shows that consciousness is not physical in our world. Since there is a possible world where consciousness is non-physical then all worlds with consciousness are worlds where it is non-physical. So the parrellel that Alderman fails to see is exactly the one he mentions. The zoombie argument establishes that we can give up on hoping for a non-reductive account of consciousness (in Alderman’s sense, since I think this is an abuse of the term).

Alterman then goes on to say,

Brown gives no indication of what he means by such qualities, but it cannot be things like mental or emotional states, because to assume those are non-physical would surely beg the question about consciousness.

Actually that is precisely what I mean and the begging of the question is intentional. It is exactly the same in the zombie case;that is the whole point of my paper!

After all of this, though, I am glad to see that Alterman agrees with the spirit of my remarks. Though his final comment is confusing. He claims that

The zombie idea is therefore somewhat effective in refuting the idea of a conceptual link between matter and mental phenomena; not a small accomplishment in light of the very strong pull that our basic scientific convictions have on our thinking as a whole. But they cannot answer any naturalistic questions, such as whether the notion of conscious experience will eventually fall out of a detailed description of the operation of brain cells. This is a matter for scientific research

I couldn’t agree more with the last bit, but it is interesting that he sees the zombie argument as targeting a conceptual link between our terms. This seems less interesting to me than it does to him. There is no conceptual link between water and H20 either so what? This, in fact, seems to be far less than the proponents of the zombie argument typically take it to show. They typically take it to show something about ontology and not merely how our concepts work…the former is a looser, the latter is something that a physicalist can live with; for now.