Eliminativism and the Neuroscience of Consciousness

I am teaching Introduction to Neuroscience this spring semester and am using An Introduction to Brain and Behavior 5th edition by Kolb et al as the textbook (this is the book the biology program decided to adopt). I have not previously used this book and so I am just getting to find my way around it but so far I am enjoying it. The book makes a point of trying to connect neuroscience, psychology, and philosophy, which is pretty unusual for these kinds of textbooks (or at least it used to be!).

In the first chapter they go through some of the basic issues in the metaphysics of the mind, starting with Aristotle and then comparing Descartes’ dualism to Darwin’s Materialism. This is a welcome sight in a neuroscience/biological psychology textbook, but there are some points at which I find myself disagreeing with the way they set things up. I was thinking of saying something in class but we have so little time as it is. I then thought maybe I would write something and post it on Blackboard but if I do that I may as well have it here in case anyone else wants to chime in.

They begin by discussing the greek myth of Cupid and Psyche and then say,

The ancient Greek philosopher Aristotle was alluding to this story when he suggested that all human intellectual functions are produced by a person’s psyche. The psyche, Aristotle argued, is responsible for life, and its departure from the body results in death.

Thus, according to them, the ordinary conception of the way things work, i.e. that the mind is the cause of our behavior, is turned by  Aristotle into a psychological theory about the source or cause of behavior. They call this position mentalism.

They also say that Aristotle’s view was that the mind was non-material and separate from the body, and this is technically true. I am by no means an expert on Aristotle’s philosophy in general but his view seems to have been that the mind was the form of the body in something like the way that the shape of a statue was the form of (say) some marble. This is what is generally referred to as ‘hylomorphism’ which means that ordinary objects are somehow composed of both matter and form. I’ll leave aside the technical philosophical details but I think the example of a statue does an ok job of getting at the basics.  The statue of Socrates and the marble that it is composed out of are two distinct objects for Aristotle but I am not sure that I would say that the statue was non-physical. It is physical but it is just not identical to the marble it is made out of (you can destroy the statue and not destroy the marble so they seem like different things). So while it is true that Aristotle claimed the mind and body were distinct  I don’t think it is fair to say that Aristotle thought that the psyche was non-physical. It was not identical to the body but was something like ‘the body doing what it does’ or ‘the organizing principle of the body’. But ok, that is a subtle point!

They go on to say that

Descartes’s thesis that the [non-physical] mind directed the body was a serious attempt to give the brain an understandable role in controlling behavior. This idea that behavior is controlled by two entities, a [non-physical] mind and a body, is dualism (from Latin, meaning two). To Descartes, the [non-physical] mind received information from the body through the brain. The [non-physical] mind also directed the body through the brain. The rational [non-physical] mind, then, depended on the brain both for information and to control behavior.

I think this is an interesting way to frame Descartes view. On the kind of account they are developing Aristotle could not allow any kind of physical causation by the non-physical mind but I am not sure this is correct.

But either way they have an interesting way of putting things. The question is what produces behavior? If we start with a non-physical mind as the cause of behavior then that seems to leave no role for the brain, so then we would have to posit that the brain and the non-physical mind work together to produce behavior.

They then go on to give the standard criticisms of Descartes’ dualism. They argue that it violates the conservation of energy, though this is not entirely clear (see David Papineau’s The Rise of Physicalism for some history on this issue). They also argue that dualism is a bad theory because it has led to morally questionable results. In particular:

Cruel treatment of animals, children, and the mentally ill has for centuries been justified by Descartes’s theory.

I think this is interesting and probably true. It is a lot easier to dehumanize something if you think the part that matters can be detached. However I am not sure this counts as a reason to reject dualism. Keep in mind I am not much of a dualist but if something is true then it is true. I tend to find that students more readily posit a non-physical mind for animals than they do deny that they have pain as Descartes did but that is neither here nor there.

Having set everything up in this way they then introduce eliminativism about the mind as follows.

The contemporary philosophical school eliminative materialism takes the position that if behavior can be described adequately without recourse to the mind, then the mental explanation should be eliminated.

Thus they seem to be claiming that the non-physical aspect of the system should be eliminated, which I think a lot of people might agree with, but also that along with it the mental items that Descartes and others thought were non-physical should be eliminated as well. I fully agree that, in principle, all of the behaviors of animals can be fully explained in terms of the brain and its activity but does this mean that we should eliminate the mind? I don’t think so! In fact I would generally think that this is the best argument against dualisms like Descartes’. We have never needed to actually posit any non-physical features in the explanation of animal behavior.

In general the book tends to neglect the distinction between reduction and elimination. One can hold that we should eliminate the idea that pains and beliefs are non-physical mental items and instead think that they are physical and can be found in the activity or biology of the brain. That is to say we can think that certain states of the brain just are the having of a belief or feeling of a pain, etc. Eliminativism, as it is usually understood, is not a claim about the physicality of the mind. It is instead a claim about how neuroscience will proceed in the future. That is to say the emphasis is not on the *materialism* but on the *eliminative* part. The goal is to distinguish it from other kinds of materialism not to distinguish it from dualism. The claim is that when neuroscience gives us the ultimate explanation of behavior we will see that there really is no such thing as a belief. This is very different from the claim that we will find out that certain brain states are beliefs.

Thus it is a bit strange that the authors run together the claim that the mind is a non-physical substance together with the claim that there are such things as beliefs, desires, pains, itches, and so on. This seems to be a confusion that was evident in early discussions of eliminativism (see the link above) but now we know we can eliminate one and reduce the other, though we may not as well.

They go on to say,

Daniel Dennett (1978) and other philosophers, who have considered such mental attributes as consciousness, pain, and attention, argue that an understanding of brain function can replace mental explanations of these attributes. Mentalism, by contrast, defines consciousness as an entity, attribute, or thing. Let us use the concept of consciousness to illustrate the argument for eliminative materialism.

I do not think this is quite the right way to think about Dennett’s views but it is hard to know if there is a right way to think about them! At any rate it is true that Dennett thinks that we will not find anything like beliefs in the completed neuroscience but it is wrong to think that Dennett thinks we should eliminate mentalistic talk. It is true, for Dennett, that there are no beliefs in the brain but it is still useful, on his view, to talk about beliefs and to explain behavior in terms of beliefs.

He has lately taken to comparing his views with the way that your desktop computer works. When you look at the desktop there are various icons there and folders, etc. Clicking on the folder will bring up a menu showing where your saved files are, etc. But it would be a mistake to think that this gave you any idea about how the computer was working. It is not storing little file folders away. Rather there is a bunch of machine code and those icons are a convenient way for you to interface with that code without having to know anything about it. So, too, Dennett argues our talk about the mind is like that. It is useful but wrong about the nature of the brain.

At any rate how does consciousness illustrate the argument for eliminative materialism?

The experimenters’ very practical measures of consciousness are formalized by the Glasgow Coma Scale (GCS), one indicator of the degree of unconsciousness and of recovery from unconsciousness. The GCS rates eye movement, body movement, and speech on a 15-point scale. A low score indicates coma and a high score indicates consciousness. Thus, the ability to follow commands, to eat, to speak, and even to watch TV provide quantifiable measures of consciousness contrasting sharply with the qualitative description that sees consciousness as a single entity. Eliminative materialists would argue, therefore, that the objective, measurably improved GCS score of behaviors in a brain-injured patient is more useful than a subjective mentalistic explanation that consciousness has “improved.”

I don’t think I see much of an argument for eliminativism in this approach. The basic idea seems to be that we should take ‘the patient is conscious’ as a description of a certain kind of behavior that is tied to brain activity and that this should be taken as evidence that we should not take ‘consciousness’ to refer to a non-physical mental entity. This is interesting and it illustrates a general view I think is in the background of their discussion. Mentalism, as they define it, is the claim that the non-physical mind is the cause of behavior. They propose eliminating that but keeping the mentalistic terms, like ‘consciousness’. But they argue that we should think of these terms not as naming some subjective mental state but as a description of objective behavior.

I do agree that our ordinary conception of ‘consciousness’ in the sense of being awake or asleep or in a coma will come to be refined by things like the Glasgow Coma Scale. I also agree that this may be some kind of evidence against the existence of a non-physical mind that is either fully conscious or not at one moment. As the authors themselves are at pains to point out we can take the behavior to be tied to brain activity and it is there that I would expect to find consciousness. So I would take this as evidence of reduction or maybe slight modification of our ordinary concept of waking consciousness. That is, on my view, we keep the mental items and identify them with brain activity thereby rejecting dualism (even though I think dualism could be true, I just don’t think we have a lot of reason to believe that it is in fact true).

They make this clear in their summary of their view;

Contemporary brain theory is materialistic. Although materialists, your authors included, continue to use subjective mentalistic words such as consciousnesspain, and attention to describe more complex behaviors, at the same time they recognize that these words do not describe mental entities.

It think it should be very clear by now that they mean this as a claim about the non-physical mind. The word ‘consciousness’ on their view describes a kind of behavior which can be tied to the brain but not a non-physical part of nature. But even so it will still be true that the brain’s activity will cause pain; as long as we interpret ‘pain’ as ‘pain behavior’.

However, I think it is also clear by now that we need not put things this way. It seems to me that the better way to think of things is that pain causes pain behavior, and that pain is typically and canonically a conscious experience, and that we can learn about the nature of pain by studying the brain (because certain states of the brain just are states of being in pain).  We can thereby be eliminativists about the non-physical mind while being reductionists about pain.

But, whichever way one goes on this, is it even correct to say that modern neuroscience is materialistic? This seems to assume too much. Contemporary neuroscience does make the claim that an animal’s behavior can be fully understood in terms of brain activity (and it seems to me that this claim is empirically well justified) but is this the same thing as being materialistic? It depends on what one thinks about consciousness. It is certainly possible to take all of what neurosciences says and still think that conscious experience is not physical. That is the point that some people want to make by imagining zombies (or claiming that they can). It seems to them that we could have everything that neuroscience tells us about it and its relation to behavior and yet still lack any of the conscious experience in the sense that there is something that it is like for the subject. I don’t think we can really do this but it certainly seems like we can to (me and) a lot of other people. I also agree that eliminativism is a possibility in some sense of that word but I don’t see that neuroscience commits you to it or that it is in any way an assumption of contemporary brain theory.

It wasn’t that long ago (back in the 1980s) that Jerry Fodor famously said, “if commonsense psychology were to collapse, that would be, beyond comparison, the greatest intellectual catastrophe in the history of our species” and I tend to agree (to a somewhat less hyperbolic way of putting the point). The authors of this textbook may advocate eliminating our subjective mental life but that is not something that contemporary neuroscience commits you to!

Levin on Brown

My paper Deprioritizing the A Priori Arguments Against Physicalism, which was a product of the online consciousness conference, directly grew out of blog discussions I had around here shortly after I started this blog in May of 2007 (which, by the way, I just noticed, means that the 10 year anniversary of Philosophy Sucks! is coming up soon!!)…at that time I had been interested in modal arguments against physicalism but had no plans at all of writing a paper on zombies. At any rate this paper has become my second most cited paper (and is even cited by the Stanford Encyclopedia of Philosophy’s entry on Zombies (and the Wikipedia one too!)) but it is usually cited en passant, so to speak, so it is nice to see some actual discussion of the argument.

Janet Levin discusses it in her paper Do Conceivability Arguments Beg the Question Against Physicalism? which was published in the 2014 issue of Philosophical Topics that I edited as a result of the 4th online consciousness conference. At the time I was putting the issue together I contemplated writing something about it in a brief response but decided to wait. ‘Better late than never’ is quickly becoming my motto!

Levin starts with Perry’s response to the zombie argument in his 2001 book Knowledge, Possibility, and Consciousness and I think this is a good place to start. As a bit of an aside Perry’s book  has been hugely influential on me. I read it in my philosophy of mind course, with Kent Bach, in the fall of 2001 and at the time I remember feeling that the identity theory was not really given the due that it deserved and then I saw Perry defending it and it gave me hope. I even invited him out to SFSU to give a talk to the philosophy club as a result and he did. This may have been my first attempt at organizing an academic event! The paper I wrote for that class, “Sticking to the Subject: My Response to Chalmers’ Response to Perry” became my writing sample when I applied to PhD programs. I rewrote it with feedback from the class and afterwards when I approached him with this as a potential writing sample….I think I used to have this up on my website at some point when I was in Connecticut but it seems to be lost now (especially after my pre-cloud computer crash back in 2004 or 2005). I  only have a vague notion of what was in that paper and it would be interesting to see it again.

(On another tangent I also recall this book influenced a paper I wrote for my epistemology class I had in the spring of 2002 (also with Kent Bach) where I argued that adopting Perry’s view showed us how we can say that when I play Resident Evil and have thoughts like “there’s a green herb in the basement” they come out true (and how this shows a way to avoid skepticism)).

…But back to Levin’s critique. Here is what she says,

In his (2010), Richard Brown argues that the zombie argument (and its relatives) beg the question; they seem compelling only to those who already assume that qualitative properties are not physical.

One thing that I think has become clear over the years is that I was not clear enough in the original paper about my background assumptions and intentions. I had been used to arguing with people like David Chalmers and Richard Chappell and they were both very strong supporters of a priori reasoning and some version of two-dimensional semantics. So when I said that the zombie argument begged the question I meant that it begged the question against a physicalist who accepted the link between conceivability and possibility. I was trying to show that even if you grant all of the other assumptions that dualists make they still do not have an argument against physicalism. I didn’t really intend this to be a claim that the zombie argument begged the question against those who accepted type-B physicalism, or who otherwise denied the link between conceivability and possibility (as I am in some moods likely to do).

So how was this supposed to play out? As Levin says, I attempt to show this by

…presenting conceivability arguments analogous to the Zombie Argument that aim to support, rather than undermine, physicalism.  In particular, Brown argues for the conceivability of Zoombies; that is (p. 50), ‘creatures non-physically identical to me in every respect and which lack any non-physical phenomenal consciousness’, and also of Shombies; that is (p. 51), ‘creature[s] that [are] microphysically identical to me, ha[ve] conscious experience, and [are] completely physical’, and suggests that arguments with such conceivability premises will seem as compelling to physicalists as the zombie argument seems to dualists.

I can see why she says this but I would like to clear this up a bit.

First, I never intended my paper to offer any support for physicalism. I took the point to be that we did not have any good reason to think it was false, or that the a priori arguments against it did not show it to be false (currently, that is. Whatever their potential to do so in the future amounts to they do not presently constitute a reason to think that physicalism is false). Perhaps this is in fact to offer some kind of indirect support for physicalism but even so the conceivability arguments she is here discussing were aimed at showing that dualism is false. So take the pair {zombie, shombie}. If one accepts a two-dimensional semantics and one buys the general arguments against strong necessitates, then only one of this pair is truly ideally conceivable and the other is necessarily inconceivable. That much is common ground between those who accept two-dimensional semantics )and I do for the purposes of this argument…and sometimes for other purposes as well). But which one of this pair is ideally conceivable? No one has really been able to show that either one leads to a contradiction.

So, as I stressed above, given this set of background assumptions then I think the zombie argument is question begging. It begs the question by assuming that it is zombies that are truly ideally conceivable and not shombies. But if I am working inside 2D semantics then I find shombies to be conceivable and so that means zombies have to be the ones that are ideally inconceivable, even if I cannot yet say why. It is at this point, from within the 2D framework that the standoff manifests most strongly. As the Stanford encyclopedia entry on zombies suggests the best option for the dualist like Dave is to maintain that shombies are inconceivable (Dave has said this as well) but when pressed on why they are all that can be said is that many people have found it very hard to see how physicalism could be true of consciousness. But that is just to say that shombies are incredible for him, just as zombies are for me.

And this is just what Levin herself says, as we’ll see below. She goes one to say,

More precisely, Brown argues that Zoombies and Shombies—along with zombies—are all prima facie conceivable, and contends (like the theorists discussed above) that one’s antecedent theoretical commitments determine one’s convictions about which of these creatures will be ideally conceivable, conceivable ‘in the limit’.  And, though he is officially neutral about what the ultimate outcome will be, he suggests that if we were to learn, and sufficiently attend to, all the (not yet discovered) physical and functional facts about the world, we would be able to recognize that these facts do indeed entail that certain of our internal states are conscious experiences.

I would balk at this way of putting things. It is true that I am neutral about which one is ultimately truly conceivable but I do not think that it must be the case that we end up being able to make these deductions. I only think this is a possibility and that it is not ruled out by the conceivability arguments against physicalism. I do think that for different people different combinations of zombies and shombies will seem to be conceivable/inconceivable and that it is one’s background theoretical commitments that tacitly determine which is which.

I will also say that one thing that has been somewhat disappointing is that the suggestion that we may be able to make deductions a priori from physical states to phenomenal states only when we have the relevant concepts, whatever those turn out to be. So, Mary cannot do it in her room unless she has the relevant phenomenal concept (I can be neutral on what exactly these are and do not mean to endorse any account of them here). I have always thought that this was the best way to respond to the Mary case and I do not see it being discussed very much. I wish it were!

The main problem Levin has with what I say is something she points out as a flaw in Perry’s argument as well. She says,

Brown characterizes his view as a species of (what Chalmers calls) Type-C physicalism, the view that, although zombies may be conceivable now, they would be inconceivable ‘in the limit’.   But of course dualists would deny this, and it’s worth getting clear about what, on Brown’s view, could account for the eventual inconceivability of zombies.  First (p. 49) he likens the (prima facie) conceivability of zombies for us now to the prima facie conceivability of H2O in the absence of water for those living in the early 18th century, and suggests that, just as further empirical discoveries made H2O without water inconceivable, so further empirical discoveries will do the same for zombies. But this argument, like the ones discussed above, relies on a questionable analogy.  At least arguably—as noted before—what enables us (and not our 18th century counterparts) to deduce water facts from H2O facts is not merely that we have increased our empirical information, although this, to be sure, is crucial.  In addition, we, at least implicitly, appeal to certain principles that go beyond one’s empirical or methodological ‘theoretical commitments’; in particular, that the referent of ‘water’ is a  (natural) kind of stuff (e.g. the stuff that fills our lakes and comes out of our faucets or, alternatively—pointing to a lake or a puddle—that kind of stuff), and that natural kinds are to be individuated by their compositional properties (such as being composed of H2O).  But it is not clear that there are analogous principles which, when combined with our knowledge of the structure and function of the brain and central nervous system, would permit the deduction of facts about conscious experience from even a complete statement of the physical and functional facts.  And thus, it seems, it is plausible to think that even those committed to physicalism and open to further information about the structure and function of the brain will continue to find zombies conceivable.

I think I partially agree with what she is saying here. Especially with respect to the ‘extra empirical’ factors relevant to theory adoption in general.

Levin’s comments can be made especially poignant for the ‘water is H2O’ example. To anyone really interested in these issues I would recommend  reading Hasok Cheng’s book Is Water H2O? Evidence, Realism, and Pluralism, which was recommended to me after a talk I gave in Taiwan at the Academia Senica. This book really clarified a lot of the technical philosophical and empirical issues about the theoretical identity of water and H2O and I think it does highlight similar kinds of extra empirical forces at work in the history of science. I highly recommend it to anyone interested in these issues. But I am not sure why this kind of point is supposed to count against  the claim I am making. It seems to me to further support it!

If I am reading Levin right it looks like she is arguing that we may be Type B physicalists at the limit. That is, we may learn all of the physical facts and yet still find that zombies are conceivable even if we become otherwise convinced that physicalism is true. I agree that this is a possibility and this is why I think it is correct to say none of these arguments (employing zombies or shombies) are question begging tout court. They beg the question against a particular way of thinking about physicalism.

I also tend to agree that in the background of my thinking is something like what she points to about natural kinds. Especially in this case where I am interested in being as close to two-dimensional semantics as possible (because part of me thinks it is nice view to have). If one takes that point of view then consciousness is similar enough in that it can be picked out by a primary intension. We can, I think, attend to specific instances of phenomenal consciousness and say ‘that kind of stuff’ and thereby pick something out. So while I agree that my way of thinking is not the only way or forced up on in any way I am more concerned with arguing that this way of thinking is not (currently) threatened by any a priori arguments.

This is because my aim is not to establish physicalism but to show that arguments aimed at undermining it don’t do so without further assumptions. Even if you grant that the ideal conceivability of zombies would show that physicalism is false we need more than that. We need to also know that zombies are in fact ideally conceivable, and that is why homies are problematic. They must be inconceivable but then why can I, and so many others, conceive of them? The reason is, I suggested, that neither side has been able to show what contradiction is (or could be) entailed by the other side. Dualists and type B physicalists correctly point out that no one has made a successful case for why zombies are  inconceivable but, less often pointed out of late, it is also the case that no one has shown what contradiction is entailed by shombies. As far as we can tell at this point either both are ideally conceivable and so 2-dimensional semantics and modal rational fail or only one of the pair is ideally conceivable and we don’t presently know which one it is.

I think that Levin herself arrives at something like this position as well, as we’ll see. She goes on to say,

In a related argument, Brown suggests (p 55) that what could permit ‘the deduction of the phenomenal facts from the physical facts is the (for us) a posteriori discovery of identities between phenomenal and physical properties’.  But given the asymmetry discussed above, one may wonder, on behalf of dualists, what makes it plausible to think that any such a posteriori discovery could occur.  The answer, Brown maintains (pp. 55-56), is that further empirical investigation is likely to show that (contrary to Chalmers, et al and also Type B physicalists) ‘we will have discovered that phenomenal properties can be explained in broadly functional terms’, and goes on to argue that ‘this does not thereby endorse Type A physicalism.  It is just to point out that I cannot really conceive of anything else doing any explanatory work…No one has ever given anything like a proper account of what non-physical properties are or how they explain phenomenal consciousness.’

This, however—as for Perry—seems to be a matter not of zombies’ being inconceivable, but rather incredible, and the plausibility of Type C physicalism depends on the plausibility of the former, stronger, claim.  In short, there is no particular reason to think that any further discoveries of the neural structure of the brain and psychological laws governing mind-body interactions will provide information of a different sort from the information we have now.  And given that there seem to be no a priori links between physical (or physical-functional) and phenomenal concepts, and no a priori principles determining the nature or essential properties of the items denoted by our phenomenal concepts (other than that they must feel a certain way), it’s hard to see how zombies could become inconceivable—even in the limit.

Here I completely agree with her and in fact I think this is part of the point that I was trying to make.  Some people seem to find zombies conceivable, some people seem to find shombies conceivable. Since I am assuming that our reasoning capabilities are good enough for this (another common assumption between Chalmers and I for this argument) that leaves only empirical or conceptual issues left. So I agree that we haven’t yet got the story. I have argued that something like the higher-order theory will help but really the larger point is that we need a theory of consciousness and empirical data to move forward.

Again I would also point out that I think that part of the story here must invoke something about how these identities could be established. Here I think we could have a 2D version but also a version like that of Ned Block (that is a non-two-dimensional account). I am attracted to both kinds of pictures about the way these identities will be discovered.

But all of that to one side the whole point is that we cannot start from the assumption that zombies are in fact ideally conceivable. They may *seem* to be so *to you* given what *we know now* but this is not at all the same thing as their actually really being ideally conceivable, as shombies show. If one or the other were truly ideally conceivable *at this point in time* then we wold be able to show what contradiction is entailed by the zombie or shombie world. Thus, until that can be done, instead of ‘physicalism is false’ the best we get from the zombie argument is ‘it seems to me now that physicalism is false’. I hope it goes with out saying that I think the same is the case for the a priori arguments from the physicalist.

On a final note, Levin says in a footnote that Thomas Nagel in his 1965 paper Physicalism discusses cases like zoombies. Zoombies were supposed to be non-physical duplicates of me which lack consciousness. These creatures have all of my non-physical properties and yet they do not have consciousness. This seems conceivable to me, but is this what Nagel is talking about? When I went and re-read that paper it seemed like a warm up for his Bat paper and at the end he is talking about indexical information (which seems to be part of the story about how I became part of PQTI in Chalmers’ work and may be a precursor to Perry’s work). Maybe this is what she meant? I might have to re-re-read it…anyone else see the similarity?

Kozuch on Lau and Brown

Way back on November 20th 2009 Benji Kozuch came and gave a talk at the CUNY Cognitive Science series and became the first to be persuaded by me to attempt an epic marathon of cognitive science, drinking, and jamming!  The mission: give a 3 hour talk followed by intense discussion over drinks (and proceeded by intense discussion over lunch) followed by a late night jam session at a midtown rehearsal studio. This monstrous marathon typically begins at noon with lunch and then concludes sometime around 10 pm when the jamming is done (drinks after jamming optional). That’s 10 hours-plus of philosophical and musical mayhem! We recorded the jam that night but it was subsequently ruined and no one has ever heard what happened that night…which is probably for the best!

This was just before our first open jam session at the Parkside Lounge (the first one was held after the American Philosophical Association meeting in NYC December 2009), which became the New York Consciousness Collective and gave rise to Qualia Fest. But this itself was the culmination of a lot of music playing going back to the summer of 2006. The last Qualia Fest was in 2012 but since then we have had two other brave members of Club Cogsci. One is myself (in 2015) and the other is Joe LeDoux (in 2016). That’s 10 year’s of jamming with cognitive scientists and philosophers! Having done it myself, I can say it is grueling and special thanks go to Benji for being such a champion.

Putting all of that to one side, Kozuch has in some recent publications argued against the position that I tentatively support. In particular in his 2014 Philosophical Studies paper he argued that evidence from lesions to prefrontal areas cast doubt on higher-order theories of consciousness (see Lau and Rosenthal for a defense of higher-order theories against this kind of charge). I have for sometime meant to post something about this (at one point I thought I might have a conference presentation based on this)…but, as is becoming more common, it has taken a while to get to it! Teaching a 6/3-6/3 load has been stressful but I think I am beginning to get the hang of how to manage time and to find the time to have some thoughts that are not related to children or teaching 🙂

The first thing I would note is that Kozuch clearly has the relational version of the higher-order theory in mind. In the opening setup he says,

…[Higher-Order] theories claim that a mental state M cannot be phenomenally conscious unless M is targeted by some mental state M*. It is precisely this claim that is my target.

This is one way of characterizing the higher-order approach but I have spent a lot of time suggesting that this is not the best way to think of higher-order theories. This is why I coined the term ‘HOROR theory’. I used to think that the non-relational way of doing things was closer to the spirit of what Rosenthal intended but now I think that this is a pointless debate and that there are just (at least) two different ways of thinking about higher-order theories. On the one kind, as Kozuch says, the first-order state M is made phenomenally conscious by the targeting of M by some higher-order state.

I have argued that another way of thinking about all of this is that it is not the first-order state that gets turned into a phenomenally conscious state. This is because of things like Block’s argument, and the empirical evidence (as I interpret that evidence at least). Now this would not really matter if all Kozuch wanted to do was to argue against the relational view, I might even join him in that! But if he is going to cite my work and argue against the view that I endorse then the HOROR theory might make a difference. Let’s see.

The basic premise of the paper is that if a higher-order theory is true then we have good reason to think that damaging or impairing the brain areas associated with the higher-order awareness should impair conscious experience. From here Kozuch argues that the best candidate for the relevant brain areas are the dorsal lateral prefrontal cortex. I agree that we have enough evidence to take this area seriously as a possible candidate for an area important for higher-order awareness, but I also think we need to keep in mind other prefrontal areas, and even the possibility that different prefrontal areas may have different roles to play in the higher-order awareness.

At any rate I think I can agree with Kozuch’s basic premise that if we damaged the right parts of the prefrontal cortex we should expect loss or degradation of visual phenomenology. But what would count as evidence of this? If we call an area of the brain an integral area only if that area is necessary for conscious experience then what will the result of disabling that area be? Kozuch begins to answer this question as follows,

It is somewhat straightforward what would happen if each of a subject’s integral areas (or networks) were disabled. Since the subject could no longer produce those HO states necessary for visual consciousness, we may reasonably predict this results in something phenomenologically similar to blindness.

I think this is somewhat right. From the subject’s point of view there would be no visual phenomenology  but I am not sure this is similar to blindness, where a subject seems to be aware of their lack of visual phenomenology (or at least can be made aware). Kozuch is careful to note in a footnote that it is at least a possibility that subjects may loose conscious phenomenology but fail to notice it but I do not think he takes it as seriously as he should.

This is because the higher-order theory, especially the non-relational version I am most likely to defend, the first-order states largely account for the behavioral data and the higher-order states account for visual phenomenology. Thus in a perfect separation of the two, that is in a case of just first-order states and no higher-order states at all then according to the theory the behavior of the animal will largely be undisturbed. The first-order states will produce their usual effects and the animal will be able to sort, push buttons, etc. They will not be able to report on their experience, or any changes therein, because they will not have the relevant higher-order states to be aware that they are having any first-order states at all. I am not sure this is what is happening in these cases (I have heard some severe skepticism over whether these second hand reports should be given much weight) but it is not ruled out theoretically and so we haven’t got any real evidence that pushes past one’s intuitive feel for these things. Kozuch comes close to recognizing this when he says, in a footnote,

In what particular manner should we expect the deficits to be detected? I do not precisely know, but one could guess that a subject with a disabled integral area would not perform normally on (at least some) tests of their visual abilities. Failing that, we could probably still expect the subject to volunteer information indicating that things ‘‘seemed’’ visually different to her.

But both of these claims are disputed by the higher-order theory!

Later in the paper where Kozuch is addressing some of the evidence for the involvement of the prefrontal cortex he introduces the idea of redundancy. If someone objects that taking away on integral area does not dramatically diminish visual phenomenology because of some other area taking over or covering for it then he claims we are committed to the view that there are redundant duplications of first-order contents at the higher-order level. But this does not seem right to me. An alternative view is that the prefrontal areas are all contributing something different to the content of the higher-orderr representation and taking one away may take away one component of the overall representations. We do not need to appeal to redundancy to explain why there may not be dramatic changes in the conscious experiences of subjects.

Finally, I would say that I wish Kozuch had addressed what I take to be the main argument in Lau and Brown (and elsewhere), which is that we have empirical cases which suggest that there is a difference in the conscious visual phenomenology of a subject but where the first-order representations do not seem like they would be different in the relevant way. In one case, the Rare Charles Bonnett case, we have a reason to think that the first-order representations are too weak to capture the rich phenomenal experience. In another case, subjective inflation, we have reason to think that the first-order states are held roughly constant while the phenomenology changes.

-photo by Jared Blank

Chalmers on Brown on Chalmers

I just found out that the double special issue of the Journal of Consciousness Studies devoted to David Chalmers’ paper The Singularity: A Philosophical Analysis recently came out as a book! I had a short paper in that collection that stemmed from some thoughts I had about zombies and simulated worlds (I posted about them here and here). Dave responded to all of the articles (here) and I just realized that I never wrote anything about that response!

I have always had a love/hate relationship with this paper. On the one hand I felt like there was an idea worth developing, one that started to take shape back in 2009. On the other hand there was a pretty tight deadline for the special issue and I did not feel like I had really got ahold of what the main idea was supposed to be, in my own thinking. I felt rushed and secretly wished I could wait a year or two to think about it. But this was before I had tenure and I thought it would be a bad move to miss this opportunity. The end result is that I think the paper is flawed but I still feel like there is an interesting idea lurking about that needs to be more fully developed. Besides, I thought, the response from Dave would give me an opportunity to think more deeply about these issues and would be something I could respond to…that was five years ago! Well, I guess better late than never so here goes.

My paper was divided into two parts. As Dave says,

First, [Brown] cites my 1990 discussion piece “How Cartesian dualism might have been true”, in which I argued that creatures who live in simulated environments with separated simulated cognitive processes would endorse Cartesian dualism. The cognitive processes that drive their behavior would be entirely distinct from the processes that govern their environment, and an investigation of the latter would reveal no sign of the former: they will not find brains inside their heads driving their behavior, for example. Brown notes that the same could apply even if the creatures are zombies, so this sort of dualism does not essentially involve consciousness. I think this is right: we might call it process dualism, because it is a dualism of two distinct sorts of processes. If the cognitive processes essentially involve consciousness, then we have something akin to traditional Cartesian dualism; if not, then we have a different sort of interactive dualism.

Looking back on this now I think that I can say that part of the idea I had was that what Dave here calls ‘process dualism’ is really what lies behind the conceivability of zombies. Instead of testing whether (one thinks that) dualism or physicalism is true about consciousness the two-dimensional argument against materialism is really testing whether one thinks that consciousness is  grounded in biological or functional/computational properties. This debate is distinct and orthogonal to the debate about physicalism/dualism.

In the next part of the response Dave addresses my attempted extension of this point to try to reconcile the conceivability of zombies with what I called ‘biologism’. Biologism was supposed to be a word to distinguish the debate between the physicalist and the dualist from the debate between the biologically-oriented views of the mind as against the computationally oriented views. At the time I thought this term was coined by me and it was supposed to be an umbrella term that would have biological materialism as a particular variant. I should note before going on that it was only after the paper was published that I became aware that this term has a history and is associated with certain views about ‘the use of biological explanations in the analysis of social situations‘. This is not what I intended and had I known that beforehand I would have tried to coin a different term.

The point was to try to emphasize that this debate was supposed to be distinct from the debate about physicalism and that one could endorse this kind of view even if one rejected biological materialism. The family of views I was interested in defending can be summed up as holding that consciousness is ultimately grounded in or caused by some biological property of the brain and that a simulation of the brain would lack that property. This is compatible with materialism (=identity theory) but also dualism. One could be a dualist and yet hold that only biological agents could have the required relation to the non-physical mind. Indeed I would say that in my experience this is the view of the vast majority of those who accept dualism (by which I mostly mean my students). Having said that it is true that in my own thinking I lean towards physicalism (though as a side-side note I do not think that physicalism is true, only that we have no good reason to reject it) and it is certainly true that in the paper I say that this can be used to make the relevant claim about biological materialism.

At any rate, here is what Dave says about my argument.

Brown goes on to argue that simulated worlds show how one can reconcile biological materialism with the conceivability and possibility of zombies. If biological materialism is true, a perfect simulation of a biological conscious being will not be conscious. But if it is a perfect simulation in a world that perfectly simulates our physics, it will be a physical duplicate of the original. So it will be a physical duplicate without consciousness: a zombie.

I think Brown’s argument goes wrong at the second step. A perfect simulation of a physical system is not a physical duplicate of that system. A perfect simulation of a brain on a computer is not made of neurons, for example; it is made of silicon. So the zombie in question is a merely functional duplicate of a conscious being, not a physical duplicate. And of course biological materialism is quite consistent with functional duplicates.

It is true that from the point of view of beings in the simulation, the simulated being will seem to have the same physical structure that the original being seems to us to have in our world. But this does not entail that it is a physical duplicate, any more than the watery stuff on Twin Earth that looks like water really is water. (See note 7 in “The Matrix as metaphysics” for more here.) To put matters technically (nonphilosophers can skip!), if P is a physical specification of the original being in our world, the simulated being may satisfy the primary intension of P (relative to an inhabitant of the simulated world), but it will not satisfy the secondary intension of P. For zombies to be possible in the sense relevant to materialism, a being satisfying the secondary intension of P is required. At best, we can say that zombies are (primarily) conceivable and (primarily) possible— but this possibility mere reflects the (secondary) possibility of a microfunctional duplicate of a conscious being without consciousness, and not a full physical duplicate. In effect, on a biological view the intrinsic basis of the microphysical functions will make a difference to consciousness. To that extent the view might be seen as a variant of what is sometimes known as Russellian monism, on which the intrinsic nature of physical processes is what is key to consciousness (though unlike other versions of Russellian monism, this version need not be committed to an a priori entailment from the underlying processes to consciousness).

I have to say that I am sympathetic with Dave in the way he diagnoses the flaw in the argument in the paper. It is a mistake to think of the simulated world, with its simulated creatures, as being a physical duplicate of our world in the right way; especially if this simulation is taking place in the original non-simulated world. If the biological view is correct then it is just a functional duplicate, true a microfunctional duplicate, but not a physical duplicate.

While I think this is right I also think the issues are complicated. For example take the typical Russellian pan(proto)psychism that is currently being explored by Chalmers and others. This view is touted as being compatible with the conceivability of zombies because we can conceive of a duplicate of our physics as long as we mean the structural, non-intrinsic properties. Since physics, on this view, describes only these structural features we can count the zombie world as having our physics in the narrow sense. The issues here are complex but this looks superficially just like the situation described in my paper. The simulated world captures all of the structural features of physics but leaves out whatever biological properties are necessary and in this sense the reasoning of the paper holds up.

This is why I think the comparison with Russellian monism invoked by Dave is helpful. In fact when I pitched my commentary to Dave I included this comparison with Russellian monism but it did not get developed in the paper. At any rate, I think what it helps us to see is the many ways in which we can *almost* conceive of zombies. This is a point that I have made going back to some of my earliest writings about zombies.  If the identity theory is true, or if some kind of biological view about consciousness is true, then there is some (as yet to be discovered) property/properties of biological neural states which necessitate/cause /just are the existence of phenomenal consciousness. Since we don’t know what this property is (yet) and since we don’t yet understand how it could necessitate/cause/etc phenomenal consciousness, we may fail to include it in our conceptualization of a ‘zombie world’. Or we may include it and fail to recognize that this entails a contradiction. I am sympathetic to both of these claims.

On the one hand, we can certainly conceive of a world very nearly physically just like ours. This world may have all/most of the same physical properties, excepting certain necessary biological properties, and as a result the creatures will behave in indistinguishable ways from us (given certain other assumptions). On the other hand we may conceive of the zombie twin as a biologically exact duplicate in which case we do not see that this is not actually a conceivable situation. If we knew the full biological story we would be, or at least could be, in a position to see that we had misdescribed the situation in just the same way as someone who did not know enough chemistry might think they could conceive of h2o failing to be water (in a world otherwise physically just like ours). This is what I take to be the essence of the Krpkean strategy. We allow that the thing in question is a metaphysical possibility but then argue that it is actually misdescribed in the original argument. While misdescribing it we think (mistakenly) we have conceived of a certain situation being true but really we have conceived of a slightly different situation being true and this one is compatible with physicalism.

Thus while I think the issues are complex and that I did not get them right in the paper I still think the paper is morally correct. To the extent that biological materialism resembles Russellian monism is the extent to which the zombie argument is irrelevant.

A Higher-Order Theory of Emotional Consciousness

I am very happy to be able to say that the paper I have been writing with Joseph E. LeDoux is out in PNAS (Proceeding of the National Academy of the Sciences of the United States). In this paper we develop a higher-order theory of conscious emotional experience.

I have been interested in the emotions for quite some time now. I wrote my dissertation trying to show that it was possible to take seriously the role that the emotions play in our moral psychology which is seemingly revealed by contemporary cognitive neuroscience, and which I take to suggest that one of the basic premises of emotivism is true. But at the same time I wanted to preserve the space for one to also take seriously some kind of moral realism. In the dissertation I was more concerned with the philosophy of language than with the nature of the emotions but I have always been attracted to a rather simplistic view on which the differing conscious emotions differ with respect to the way in which they feel subjectively (I explore this as a general approach to the propositional attitudes in The Mark of the Mental). The idea that emotions are feelings is an old one in philosophy but has fallen out of favor in recent years. I also felt that in fleshing out such an account the higher-order approach to consciousness would come in handy. This idea was really made clear when I reviewed the book Feelings and Emotions: The Amsterdam Symposium. I felt that it would be a good idea to approach the science of emotions with the higher-order theory of consciousness in mind.

That was back in 2008 and since then I have not really followed up on any of the ideas in my dissertation. I have always wanted to but have always found something else at the moment to work on and that is why it is especially nice to have been working with Joseph LeDoux explicitly combining the two. I am very happy with the result and look forward to any discussion.

Existentialism is a Transhumanism

In the academic year 2015-2016 I was the co-director, with my colleague Naomi Stubbs, of a faculty seminar on Technology, Self, and Society. This was part of a larger three year project funded by a grant from the NEH and supported by LaGuardia’s Center for Teaching and Learning.  During my year as co-director the theme was Techno-Humanism and Transhumanism. You can see the full schedule for the seminar at the earlier link but we read four books over the year (in addition to many articles). In the Fall 2015 semester we read  The Technohuman Condition by Braden Allenby, and Superintelligence by Nick Bostrom. In the Spring semester we read The Future of the Mind by Michio Kaku, and Neuroethics, an anthology edited by Martha Farah. In addition to the readings Allenby and Kaku both gave talks at LaGuardia and since we had room for one more talk we invited David Chalmers who gave his paper on The Real and the Virtual (see short video for Aeon here).

All in all this was a fantastic seminar and I really enjoyed being a part of it. I was especially surprised to find out that some of the other faculty had used my Terminator and Philosophy book in their Science, Humanism and Technology course (I thought I was the only one who had used that book!).  The faculty came from many different disciplines ranging from English to Neuroscience and I learned quite a bit throughout the process. Two things became especially clear to me over the course of the year. The first is that many of my view can be described as Transhumanist in nature. The second is that a lot of my views can be described as Existentialist in nature.

The former was unsurprising but the latter was a bit surprising. I briefly studied Sartre and Existentialism as an undergraduate at San Francisco State University from 1997-1998 and I was really interested in Sartre’s work after that (i.e. I searched every book store in SF for anything Sartre related, bought, read it, and argued endlessly with anyone around about whether there was ‘momentum’ in consciousness). However once I got to Graduate School (in 2000)  I began to focus even more on psychology, neuroscience, and the philosophy of mind and I gradually lost contact with Sartre. I have never really kept up with the literature in this area (but I have recently read the Stanford Encyclopedia of Philosophy entries on Sartre and Existentialism), haven’t read Sartre in quite a while (but I did get out my copy of Being and Nothingness and Existentialism is a Humanism a couple of times during the seminar), and don’t work on any explicitly Sartrean themes in my published work (though there are connections between higher-order theories of consciousness and Sartre) but during this last year I found myself again and again appealing to distinctly Sartrean views, or at least Sartrean as I remembered it from being an undergraduate! By the end of it all I came to the view that Existential Transhumanism is an interesting philosophical view and probably is a pretty good descriptor for what I think about these issues. So, all that having been said, please take what follows with a grain of salt.

The core idea of existentialism as I understand it is a claim about the nature of persons and it is summed up in Sartre’s dictum that ‘existence precedes essence’. Whatever a person is you aren’t born one. You become one by acting, or as Sartre might put it, we create ourselves through our choices. Many interpret that claim as somehow being at odds with physicalism (Sartre was certainly a dualist) while I do not. But what does this mean? It helps to invoke the distinction between Facticity and Transcendence. Facticity relates to all of the things that are knowable about me from a third person point of view. It is what an intense biographer could put together. But I am not merely the sum total of those facts. I am essentially a project. An aiming toward the future. This aiming towards something is the way in which Sartre interpreted the notion of intentionality. All consciousness, for him, was necessarily directed at something that was not itself part of consciousness. This is why Sartre says ‘I am not what I am and I am what I am not”. I am not what I am in the sense of not being merely my facticity. I am what I am not in the sense that I am continually creating myself and turning myself into something that I was not previously.

Turning now for the moment to Transhumanism, I interpret this in roughly the same way as the World Transhumanist Association does. That is, as an extension of Humanism. Reason represents the best chance that Human Beings have of accomplishing our most cherished beliefs. These beliefs are enshrined in many of the world’s great religions and espouse principle of universality (all are equal in some sense), and compassion. Transhumanists see technology, at least in part, as a way of enhancing human reason and so as a way of overcoming our natural limitations.

One objection to this kind of project is that we could modify ourselves to the point of no longer being human, or to the point of our original selves not existing any further. Here I think the existentialist idea that there are no essential properties required to be human can help. We are defined by the fact that we are ‘a being whose being is in question’. That is we are essentially the kind of thing which creates itself, which aims towards something that is not yet what it is. Once one takes this kind of view one sees there is no danger in modifying ourselves. This seems to me to be very much in line with the general idea that the kinds of modifications the transhumanist envisions are not different in kind from the kind we have always done (shoes, eyeglasses, etc). Even if we are able to upload our minds to a virtual environment we may still be human by the existentialist definition.

In addition, another objection which was the central objection in the Allenby book, is that the Transhumanist somehow assumes a notion of the individual, as an independent rational entity, which doesn’t really exist. This may be the case but here I think that existentialism is very handy in helping us respond. The kind of individual envisioned by the Enlightenment thinkers may not exist but one way of seeing the transhumanist project is as seeking to construct such a being.

Enlightenment, in Kant’s immortal words, is

….man’s release from his self-incurred tutelage. Tutelage is man’s inability to make use of his understanding without direction from another. Self-incurred is this tutelage when its cause lies not in lack of reason but in lack of resolution and courage to use it without direction from another. Sapere aude! ‘Have courage to use your own reason!’- that is the motto of enlightenment

To this the transhumanist adds that Kant may have been wrong in thinking that we have enough reason and simply need the courage to use it. We may need to make ourselves into the kinds of rational beings which could fulfill the ideals of the Enlightenment.

There is a lot more that I would like to say about these issues but at this point I will briefly mention two there themes that don’t have much to do with existentialism. One is from Bostrom (see a recent talk of his at NYU’s Ethics of A.I. conference). One of Bostrom’s main claims is what he calls the orthogonality thesis. This is the claim that intelligence and values are orthogonal to each other. You can pair any level of intelligence with any goal at all.  This may be true for intelligence but I certainly don’t believe it is true for rationality.

Switching gears a bit I wanted to mention David Chalmers’ talk. I found his basic premise to be very convincing. The basic idea seemed to be that virtual objects count as real in much the same way as concrete objects do. When one is in a virtual environment (I haven’t been in one yet but I am hoping to try a Vive or a Playstation VR set soon!) and one interacts with a virtual dragon, there really is a virtual object that is there and that one is interacting with. The fundamental nature of this object is computational and there are some data structures that interact in various ways so as to make it roughly the same as ordinary objects and their atomic structure. Afterwards I asked if he thought the same was true for dreams. It seemed to me that many of the same arguments could be given for the conclusion that in one’s dreams one interacted with dream objects which were real in the same way as virtual objects. He said that perhaps but it depended on whether one was a functionalist about the mind. It seems to me that someone like Chalmers, who thinks that there is a computational/functional neural correlate for conscious states, is committed to this kind of view about dreams (even though he is a dualist). Dream objects should count as real on Chalmers’ view.

Professor Shombie

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! 🙂