Consciousness

The Overflow Cup Runneth Over

Richard Brown 4 Comments

There has been a lot of action on the overflow front lately! It started with papers by Ned Block and Dennett and Cohen in Trends in Cognitive Science (Block’s paper criticized, among others, my recent paper on this stuff). These articles spawned a response by me here and here, which I still stand by.

But now, having read the response from Kouider (which echoes his response given at his CUNY Cogsci talk) as well as the response from Overgaard and Block’s response to both of them in addition to Lamme’s response to Cohen and Dennett and their response in turn, it seems a couple points should be emphasized.

Accessed vs. Accessible
Block again and again says that his argument does not depend on inaccessible consciousness but rather on it being necessary that at any given moment there is some consciousness that is not accessed (but could be accessed at a different moment and so is not inaccessible tout court). There seem to me to be several issues worth considering here.

First is that there is a conceptual question about what it means to say that something is accessible but not accessed. One might think that you cannot know that something is accessible without it actually being accessed. Block and others respond that something is accessible when, roughly, it is globally broadcast. But then we might wonder why we ought to think that being globally broadcast is equivalent to being accessible. Aren’t their mental contents/states that are globally broadcast but which are not accessible? David Rosenthal has pressed this kind of question in conversation and I am not exactly sure what the neuropsychological answer is in this case. Is there any serious neuropsychological reason to think that global broadcasting is equivalent to being accessible?

Second one might worry about the ‘thin edge of the wedge’ implications of Block’s argument. If we can show that there is consciousness that is not accessed then it seems a short step to consciousness that is inaccessible in principle. And if it is true that there is a principled connection between the two then though it would be strictly speaking true that Block’s argument did not rely on inaccessible consciousness it would none the less still be appropriate to give a reductio of his argued for view in terms of absurdities in the view it leads to.

Finally, it does seem as though there is a principled connection between the two notions. Block argues that it is inappropriate to argue against the claim that there is inaccessible consciousness because he only requires that some consciousness not be accessed not inaccessible. But if one thinks just of a particular moment in consciousness leaving aside the next moment it is of course true that some consciousness is inaccessible. It is inaccessible at that moment. Block’s view is that at any given moment in your daily conscious experience there is, necessarily, some parts of your conscious experience that are inaccessible at that moment. Because of this his view really does have all of the problems associated with in principle inaccessible consciousness.

Given these considerations I don’t think that the appeal to the distinction between not accessed and inaccessible helps make Block’s case.

Kouider’s Data Count Against His Own View?
Block has said several times that Kouider’s own data counts against the no-overflow view. He says in his latest response,

According to the hypothesis Kouider et al. put forward, what is in consciousness before the cue are generic representations plus specific representations that are too sparse to provide the information necessary to explain partial report superiority. However, on their hypothesis one would expect a substantial error rate concerning the uncued items. However, Kouider et al. found the error rate to be small: their own evidence counts against them.

It really is not clear to me why Block thinks that one would expect a substantial error rate concerning the uncued items. He seems to be thinking that the no-overflow view is committed to only generic phenomenology before the cue but this is clearly not the case. It is compatible with the no overflow view that there is some specific phenomenology before the cue (just not all of the items as per overflow).

But even if one is not moved by this there is an obvious problem with the argument. The no overflow position maintains that there is enough information unconsciously processed to do the task. Subjects don’t make a lot of errors because that information was there whether consciously or not.

Falsifiability vs. Support by the Evidence
I think that Block is right that we do not want falsifiability as a=our standard here and that we need to evaluate theories holistically based on the widest swath of available evidence and theories available to us. Block thinks that there is some evidence that the kinds of unconscious processes necessary to sustain the no overflow view aren’t there. But this evidence is very weak and the jury is still out on this issue. In general the science is all over the place on this issue. There is partial evidence on both sides and no theory comes out on top on the basis of current scientific evidence alone. Hopefully this will change in the nearish future but at this point this is where it is.

Given this one might think that we should be agnostic about whether overflow is true or not but this doesn’t seem right to me. The overflow hypothesis is radical in that it postulates a kind of consciousness that cannot in principle be accessed (at that moment) and yet which is also for me in the way that normal accessed consciousness is for me. That is, I experience the unaccessed consciousness as mine without being aware that I do. How this could be so is deeply mysterious and perhaps in principle untestable with any known scientific methods. Barring prejudice in its favor we would need strong evidence indeed to accept such a notion.

Explaining Cartesian Consciousness

Richard Brown 2 Comments

In his classic paper “Two Concepts of Consciousness” David Rosenthal says “…if consciousness is essential to mentality no informative, nontrivial explanation of consciousness is possible” (2005 p 22). The claim is, roughly, that if all mental states are conscious and if there are no mental states that can occur unconsciously, then we cannot explain what makes a mental state conscious. But this assumes a certain way of characterizing the claim that all mental states are consciousness.

In a really excellent paper that just came out in Philosophers’ Imprint by Allison Simmons, Cartesian Consciousness Reconsidered, she argues that Descartes’ can understand consciousness as a kind of self-representation and can account for ‘unconscious’ mental states by appealing to gradations of consciousness and what she calls ‘phenomenal confusion’. I think she makes an excellent case that a Cartesian picture of the mind can go a long way towards providing an explanation of conscious and (seeming) unconscious states.

Yet even so, I think we can see that the initial claim made by Rosenthal is still true in a sense. The Cartesian moves made by Simmons all rely on a prior account of mentality. That is, the Cartesian explanation given relies on a prior understanding of sensations (as having objects as their ‘objective reality’, which we would translate as ‘having representational content’) and explains consciousness in terms of a thought having as it objective reality a first-order state (i.e. consciousness is the representation of our first-order states). In fact Simmons seems to make much the same point in her paper. If we interpret Descartes as claiming that thoughts and consciousness are identical then we will not be able to explain it. But, as she shows, this is not something that a Cartesian is committed to. So even if one is attracted to the view that all mental states are conscious one doesn’t need to give up on an explanation of what consciousness is.

Clip Show ‘011

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It’s that time of year again! Here are the top posts of 2011 (see last year’s clip show and the best of all time)

–Runner Up– News Flash: Philosophy Sucks!

Philosophy is unavoidable; that is part of why it sucks!

10. Epiphenomenalism and Russellian Monism

Is Russellian Monism committed to epiphenomenalism about consciousness? Dave Chalmers argues that it is not.

9. Bennett on Non-Reductive Physicalism

Karen Bennett argues that the causal exclusion argument provides an argument for physicalism and that non-reductive physicalism is not ruled out by it. I argue that she is wrong and that the causal exclusion argument does cut against non-reductive physicalism.

8. The Zombie Argument Requires Phenomenal Transparency

Chalmers argues that the zombie argument goes through even without an appeal to the claim that the primary and secondary intension of ‘consciousness’ coincide. I argue that it doesn’t. Without an appeal to transparency we cannot secure the first premise of the zombie argument.

7. The Problem of Zombie Minds

Does conceiving of zombies require that we be able to know that zombies lack consciousness? It seems like we can’t know this so there may be a problem conceiving of zombies. I came to be convinced that this isn’t quite right, but still a good post (plus I think we can use the response here in a way that helps the physicalist who wants to say that the truth of physicalism is conceivable…more on that later, though)

6. Stazicker on Attention and Mental Paint

Can we have phenomenology that is indeterminate? James Stazicker thinks so.

5. Consciousness Studies in 1000 words (more) or less

I was asked to write a short piece highlighting some of the major figures and debates in the philosophical study of consciousness for an intro textbook. This is what I came up with

4. Cohen and Dennett’s Perfect Experiment

Dennett’s response to the overflow argument and why I think it isn’t very good

3. My Musical Autobiography

This was big year for me in that I came into possession of some long-lost recordings of my death metal band from the 1990’s as well as some pictures. This prompted me to write up a brief autobiography of my musical ‘career’

2. You might be a Philosopher

A collection of philosophical jokes that I wrote plus some others that were prompted by mine.

1. Phenomenally HOT

Some reflections on Ned Block and Jake Berger’s response to my claim that higher-order thoughts just are phenomenal consciousness

Cognitive Access: The Only Game in Town

Richard Brown 6 Comments

[cross-posted at Brains]

In Ned Block’s recent paper, published in Trends In Cognitive Science, he has defended his argument that perceptual consciousness overflows cognitive access from several recent objections (including mine). It is important that Block is defending overflow from cognitive access since he admits that perceptual consciousness does not overflow all access. Phenomenal consciousness consists in there being something that it is like for the subject of the experience and this suggests that there must be some kind of access to the experience. Block has elsewhere argued that some non-cognitive form of access can account for this but no account of non-cognitive access to date can explain what needs to be explained. Given this the anti-overflow position should remain the default until/unless we have much stronger evidence than what Block presents. Block suggests that there is a philosophical fallacy in the assumption that non-overflow is the default and in the insistence that we need strong evidence to overthrow the non-overflow position but this is not fallacious. It is the reasonable thing to do when you have very weak evidence that is consistent with two competing theories and one of those theories appeals to a mysterious place-holder concept while the other doesn’t.

Block suggests two possible forms of non-cognitive access. The first is a deflationary account and the second is a version of a self-representational theory.  On the deflationary account we are aware of our mental states just in the having of them, in much the same way that we smile our own smiles just by smiling. Recall that what we are trying to explain is how a particular experience comes to be for the person who has it. When I feel a pain, not only do I experience the painful quality but I also experience it as mine. How can the deflationary account handle this? The deflationary account applies equally well to any state that happens to be instantiated in the brain. We can say that we are aware, in this way, of a state in the LGN, for instance, but surely we don’t want to say that it is phenomenally conscious.

The same problems arise for a self-representational account. One kind of self-representational account, holds that the higher-order awareness is itself a part of the state that it represents. But this is a variant of a cognitive access theory. Block seems to want a notion of self-representation that amounts to the state in question merely being instantiated (in the way a color sample represents the color just by being that particular color). But then every state would be conscious since every state represents itself merely by being instantiated. In fact every representation self-represents itself in this way but we don’t want to say that sentences are phenomenally conscious!

These notions of non-cognitive access are too weak to distinguish conscious mental states from unconscious mental states, or from any kind of brain activity at all. On the other hand a higher-order cognitive representation explains how a mental state can be for me; I am representing myself as being in that state, in some suitable way, so I will naturally experience the state as mine.

Block endorses only the reasonableness of tentatively accepting the overflow conclusion. But until we have a notion of non-cognitive access that can explain how a mental state can be experienced as mine that is at least as satisfactory as that given by cognitive access we need much stronger evidence than what Block presents to accept overflow.

Some Drafts

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Here are some recent paper drafts I have been working on, in various stages of being rewritten for various projects. Comments are most welcome!

  • Zombies and Simulation
    • a brief paper arguing that one way to conceive of philosophical zombies is conceiving of a ‘perfect’ simulation of a creature for whom a consciousness-as-biological view is true. Thus physicalists who think of consciousness as biological can admit that zombies are conceivable (even possible) with no consequence to physicalism.
  • The Identity Theory in 2D
    • a short paper sketching an updated version of the type-type identity theory in a two dimensional framework. The resulting view is similar to Lewisian functionalism but combined with a posteriori identities and gives a unified response to all a priori arguments (part of a larger project of taking back a priori reasoning for the physicalist. It seems to me to be a historical accident that a priori arguments are primarily used to argue against physicalism)
  • The Emperor’s New Phenomenology? The Empirical Case for Conscious Experience without First-Order Representations
    • a longer paper written with Hakwan Lau arguing that some kind of higher-order approach to consciousness can make better sense of some key empirical evidence.

Sid Kouider on Partial Awareness

Richard Brown 4 Comments

[Cross-posted at Brains]

So much has been going on in nyc that I have had trouble keeping up with it. However I have a bit of free time today and wanted to jot down a few notes about Sid Kouider’s recent presentation at the CUNY CogSci Colloquium. Sid was addressing a topic close to my heart, which the the issue of phenomenological overflow (I am pretty sure his talk was based on his recent TICS paper). In his talk he first gave several arguments against the notion of overflow and then gave his account of what is going on in the cases at issue.

One of his arguments was against the idea of inaccessible phenomenology in general. His idea seemed to be that phenomenology that was inaccessible could not, in principle, make any contribution to the awareness of the individual and so the fact that subjects were able to report that they had rich experiences was some evidence that they had at least some access to the information and so counted against the inaccessibility of those states. Ned Block objected that there was a confusion between something being inaccessible and something being necessarily un-accessed. Something is inaccessible (roughly) when there is no possibility that it could be accessed. Ned admitted that he probably does believe in inaccessible consciousness but was very clear that he does not think that the phenomenological overflow argument relies on this claim. Rather, the phenomenological overflow argument relies on the claim that some phenomenology is necessarily un-accessed at any given time. This is compatible with the claim that it could be accessed at some other time. So, the argument requires only that there is always more to what we are consciously experiencing than we can access at any given time not that there is some conscious experience that is completely inaccessible.

I objected at this point that Sid’s argument seemed to withstand this point. In general I think that this distinction of Ned’s is useful for clearing up a potential confusion about how the argument is supposed to work but it does not abolish the point that Sid was making. In fact, this point has been made, in a slightly different way by David Rosenthal and myself (in the paper linked to above). Subjects report that they see a bunch of letters in the Sperling type cases and that they see all or most of the rectangles in the Sligte type cases so they must have at least partial access to the first-order state. Taking their reports at face value actually counts against the notion of overflow.

A large part of the discussion at this point centered on Sid’s argument that there is an observer effect here that should push us away from thinking about unaccessed phenomenology. His argument seemed to be that any way we could possibly test for it would run afoul of the confound that access was involved (a version of the methodological puzzle). A few people objected that Sid was raising the bar to high here and demanding standards which exceed those of ordinary science. Shouldn’t we avoid the trap of thinking that there is something special about consciousness and accept regular scientific standards of when it is and isn’t around? If so it seems we could overcome the observer effect by accumulating enough ‘circumstantial’ evidence to convince us one way or the other. Dave Chalmers at this point made a comparison to the way we think about tables and chairs. I know that there is a table here because I see it (I access it), and I can’t prove that it is there unless I access it, yet none the less I go on being reasonably confident that the table continues to exist when I am not accessing it. Might not the same be true for consciousness? For my part I think that this kind of thinking is often behind the intuitions of those who endorse phenomenological overflow but I don’t find it very convincing. I agree that I think the table is there when I am not looking at it, but I do not assume that the table is there as it appeared to me! That is, the table as unaccessed (unseen) does not look like the table that I see! The table as unaccessed is, according to our best theories, either a swarm of particles or a local collapse in a wave function, or what have you…this is not how it appears to me. So too, we can agree that the accessed thing is still there without thinking that it is there as it was when I accessed it. The qualitative state is there, but when unaccessed it is not like anything for me to have it and so there is no phenomenology present.

Sid then went on to discuss his partial awareness hypothesis, which amounts to the claim that we can have access at many different levels. So, in the Sperling type cases, the subjects will have access to the semantic meanings of the letters in the cued row and only partial access to the letters in the uncured row. To have partial access is to access a lower stage of the processing hierarchy. For instance, he presented data that showed that subjects in a Stroop-like paradigm that were presented with fake color words (like ‘geren’) would treat them like color words (i.e. exhibit strop interference) only when they expected that there were going to be some color words (strong prior confidence) and also were in conditions where the words were very hard to detect (see his paper for details).

At this point Ned objected that he and Sid agreed on how to interpret the experimental results. For Sid the subjects in Sperling cases have full access to the semantics meaning of the letters in the cued row and only partial access to the letters in the inched rows. Ned pointed out that on his view he thinks that the subjects have a conscious experience of the letters in the cued row and have degraded conscious experience of the others in the uncured rows. He has always said that the phenomenology in the uncured rows is unable to be brought under the correct concepts that would allow the subject to know the identities of the letters. This sounds just like what Sid has said and so it sounds like Sid is endorsing phenomenological overflow. But this is incorrect. Sid has agreed that the subjects have the phenomenology that Ned says that they do, but on Sid’s view they have that conscious experience because they have partial access to the first order states! On Ned’s view they do not have access to those states in any way and still have phenomenology. So Sid has not endorsed overflow of any kind. The subjects have just as much conscious experience as they can access. Since they have access only to low level processing of uncured row their conscious experience will be partial as well, but since they del so confident that they are seeing letters they mistakenly report that they consciously see all of the letters. All of this can be said without having to endorse the notion of phenomenological overflow. All in all then, the no overflow view is the most parsimonious; a conclusion with which I totally agree! 🙂

Stazicker on Attention and Mental Paint

Richard Brown 3 Comments

On Monday I attended a discussion of James Stazicker‘s paper Attention, Visual Knowledge, and Psychophysics. I have talked about Block’s argument before that recent experimental work on attention suggests that there is mental paint (i.e. that there is more to phenomenology than what’s in the world or in our representations of it). In this paper Stazicker wanted to offer an account of the representational contents of vision that denied any kind of illusion (like Block) but at the same time rejected Block’s argument for mental paint (Stazicker says that his view is compatible with mental paint but not with the argument that Block gives for it).

The basic idea that Stazicker wants to develop is that vision represents determinable properties rather than determinate properties. That is to say that our visual representations while we are looking at a line of (say) 5 centimeters will be something to the effect of a line that is, say, 4.5-5.25 centimeters long. If this is right then there are many different ways of veridically representing the line of 5 cm length. We could represent it, as above, or as 4.75-5.5 or many others. Stazicker wants to maintain that these two different representations will produce different phenomenologies but that each is perfectly veridical. If this is what happens in Carrassco type cases then we can still say that our belief are veridical even though we agree that attention changes our phenomenology. He also argues that we have independent reason to think that vision does deal in determinable representations stemming from considerations about the limited spatial resolution of our representations.

Block is aware of this kind of objection and responds to it in Attention and Mental Paint. As he says,

The problem with this proposal is that it if the phenomenology of perception flows from representational content, then indeterminacy in content would have to be reflected in an indeterminacy of look. But there need be no such indeterminacy.

If our experience represents something indeterminately as, say, 4.5-5.25 cm in length then we should expect the phenomenology to be indeterminate as well, but since our phenomenology isn’t this way we have some evidence that there is more to it than the indeterminate representation; there is also the phenomenological mode of presentation, that is what it is like for the subject to have that conscious experience.

Stazicker responds to this line of argument in the paper. He argues that there is no problem with saying that our phenomenology is indeterminate. He denies that saying that conscious experience is indeterminate is the same as saying that it is blurry (though blurriness does involve indeterminacy, it also involves something else, something like the phenomenology of blurriness), nor is it the same as representing a disjunct of possibilities. He rather appeals to notions of seeing things in the distance. When one sees something that is far away one’s representations are indeterminate but without being burry or fuzzy or disjointed.

During the discussion Dan Shargel brought up the issue of how we can tell if our normal conscious vision is blurry or not. He reported an experience of having his prescription updated on his glasses. Suddenly he realized that his vision had been blurry before but had not realized that it was that way before the update. Perhaps that is what conscious vision is like for us. Block argued that there is a phenomenological difference between seeing a clear image blurrily and seeing a blurry image clearly. In each case one would be tempted to say that a subject would draw the same ‘pixel array’ even though there is a distinct phenomenological difference (the difference between feeling like you see it clearly or blurrily). Block also argued that one could not cash this out merely in terms of determinable versus determinate contents. Chalmers suggested that you might be able to capture that difference representationally in the following way. In the case of seeing the blurry image clearly one has a visual experience which represents the various smudges in a very determinate way (so one has a determinate representation of the indeterminate thing itself), whereas when one see a clear image blurrily one has an indeterminate visual experience in that one represents the determinate thing in a smudged way. Block insisted that this did not meet his objection since one would end up drawing the same thing in both cases.

I have to admit that I lean towards Block view here. It does seem to me that conscious visual experience presents things as being some determinate way. So, when I look at the frame of a painting it seems to me that the frame has some determinate length even though I am unsure what that length is. One interpretation I have long been attracted to is to see higher-order thought-like states as (phenomenal) modes of presentations for first-order sensory qualities. The higher-order states may very well represent the indeterminate first-order states as being determinate. This would allow one to endorse Block’s view that experience doesn’t seem indeterminate while also taking the empirical evidence to suggest that first-order states are indeterminate.

Bennett on Non-Reductive Physicalism

Richard Brown 4 Comments

I just re-read Karen Bennett’s paper Exclusion, Again. In this paper she argues that causal exclusion arguments provide a nice overall argument for physicalism but do not cut against non-reductive physicalism as usually thought.

Here is how she defines non-reductive physicalism.

Let us begin with the ‘physicalism’ part. It is notoriously hard to define it adequately, but I can at least offer up the same slogans as everyone else. Physicalists not only endorse the completeness of physics, but also think that all the facts are physical facts—that there is nothing ‘over and above’ the physical. Physicalists believe that everything globally supervenes6 on the physical as a matter of metaphysical necessity (see Lewis 1983, Chalmers 1996, and Jackson 1998; see Hawthorne 2002 for interesting challenges to their definitions). That is, physicalists deny that it is merely nomologically impossible for there to be a world physically just like this one but mentally different. There are no special psychophysical laws that link or tether the mental to the physical, and that can be broken.

She is officially neutral on the issue of the a priori entailment of the mental by the physical but she clearly rejects the metaphysical possibility of zombie worlds. So, what, then, is non-reductive about her view?

Nonreductive physicalists do not think—or, at any rate, should not think—that mental events and properties really are not identical to any physical ones. All we think is that they are not identical to any standard physical ones. We have no reason to deny that they are identical to physical events and properties reachable by extension or analogy with standard ones. Let me try to put this marginally more carefully, by loosely distinguishing between a narrow and a broad sense of ‘physical’.

What she means by this seems to be the following. On the one hand we have ‘narrow’ physical properties, events, or objects, which means that they figure in the laws of a ‘clearly physical’ science. So she will count neurons as narrow physical objects because they figure in neuroscience. She will also count electrons and elements, etc. On the other hand there are what she calls ‘broad’ physical properties, events, or objects, which means that we can construct the thing in question out of the narrow properties in some ‘clearly articulated’ way. So,

Broadly physical properties are those constructed from narrowly physical ones by means of property-forming operations like disjunction, conjunction, and quantification (though presumably not negation!). Broadly physical events are those constructed from narrowly physical ones by means of various forms of spatio-temporal, mereological, and modal gerrymandering. And so on. This list is merely supposed to give the general idea, and presumably needs to be expanded and tweaked in various ways.

Given these two notions she formulates non-reductive physicalism as the view that mental states are broadly physical but not narrowly physical. She thus finds it to be a mistake on the part of the non-reductive physicalist to claim that mental properties are not physical at all. They are physical, just not in the narrow sense. There is no neurological state that she will want to say is identical to the mental state, though the mental state is constructed out of those narrow states. So on her view the functional characterization of mental states picks out some narrow physical property as its realizer. When thought of in this way, she continues, non-reductive physicalism has no worries with casual exclusion but dualists do.

The crux of the argument is that if one really wants to maintain a role for the mental in causation you must endorse some kind of over-determination and if that is the case then the following two counterfactuals must be non-vacuously true (which I take to mean; true because the antecedent is true):

(O1) if m had happened without p, e would still have happened and
(O2) if p had happened without m, e would still have happened.

These are supposed to capture our ordinary understanding of overdetermination. Had there been only one of the causes the effect would have been produced by the other cause, and vice versa. The real action is over (O2). She argues that only a physicalist can interpret it in the required way. That is, only the physicalist can say that it is either vacuous or false. A physicalist will think it is vacuously true just in case she thinks that it is impossible that p happen without m. If that is false then (O2) is vacuously true. The dualist has to deny this (zombie worlds are worlds where p happens without m and e happens) and so the dualist cannot say that (O2) can ever be vacuously true. The physicalist can also say that it is false. How? Bennett argues that (O2) is false when we have p ‘out of context’. So, if we replicate the brain state that is pain in the normal brain in some petri dish or if that state were hooked up in some strange/unusual fashion it will be false that e would still come about. The effect depends on the state being in a normally functioning brain in an environment, etc. So in those cases (O2) is false. Bennett then goes on to argue that the dualist cannot take this option. This is because,

doing so would abandoning standard ways of evaluating counterfactuals. For the dualist, the closest world in which the C-fibers fire without pain is not a world in which various surrounding physical facts go differently. It is not a world in which the C-fiber firing takes place in a petri dish, or otherwise without crucial background conditions that actually obtain. It is instead a world in which the psychophysical law linking firing C-fibers in such and such circumstances to pains is violated. It is not a full-blown zombie world, mind you—that would clearly involve the kinds of “big, widespread, diverse violations of law” that Lewis says it is of the first importance to avoid (1979, 47). It is instead simply a world in which just that particular physical occurrence fails to give rise to the sort of mental one that usually accompanies it. That is merely a “small, localized, simple violation of law,” that allows us to “maximize the spatio- temporal region throughout which perfect match of particular fact prevails” (47-48). This one tiny little violation of psychophysical law is a lot easier to accomplish—if it can be accomplished at all—than a big sweeping change in circumstances.

If all of this is right, she concludes, then only the non-reductive physicalist (or the reductive physicist) can avoid the exclusion problem.

But this doesn’t seem right to me. It is wrong to say that the closest possible world where we have p without m is one where there is a small violation of the bridging laws. At least not if one is thinking in terms of the kind of dualism that Dave Chalmers advocates. Since he thinks that consciousness and mental activity are functionally invariant, under normal conditions, he can happily accept that in the cases that Bennett cites (O2) will be false. Sure they do in fact think that there are worlds like the ones that Bennett talks about where the is a local violation of a law and sure Bennett does not really think that there are any such worlds (I tend to agree) but the point is that the worlds that Bennett thinks falsify (O2) are closer to the actual world on both accounts. In those worlds no laws are violated. So the property dualist can say that (O2) is false when you have p without m in the way that Bennett talks about (i.e. p without the general background conditions that let p function normally) but that it is true when you have p without m in the law-violating way. Thus the property dualist can think that (O2) is false in the usual cases, just like the non-reductive physicalist.

Thus if the causal exclusion argument is an argument for physicalism it is an argument for reductive physicalism.

[cross posted at Brains]

Cohen & Dennett’s Perfect Experiment

Richard Brown 7 Comments

I was re-reading Dennett and Cohen’s recent paper in Trends in Cognitive Science, “Consciousness Cannot be Separated from Function” and I am now puzzled by their view (before I go on, I would like to note that this issue of TICS also has Joe LeDoux’s paper where he mentions the Qualia Fest, and Lau & Rosenthal’s paper…all in all a great issue!).

Cohen and Dennett want to argue against phenomenological overflow, which is a debate I am currently in the middle of myself, by showing that it is essentially an unscientific view. To do this they introduce what they call the ‘perfect experiment’. They imagine that the area of the brain that is responsible for processing color is somehow allowed to function but is isolated in such a way that it cannot be accessed. The subject in this experiment is shown a blue cup, say, and will deny that they see the color even though the isolated brain area is doing what it normally does. They say,

In spite of this frank denial by subjects, theories that posit dissociation between consciousness and function would necessarily assume that participants of the ‘perfect experiment’ are conscious of the apple’s color but simply cannot access that experience. After all, the conditions these theories stipulate for phenomenal consciousness of color are all met, so this experiment does not disprove the existence of isolated consciousness; it merely provides another particularly crisp example of consciousness with- out access.

However, there is a crucial problem with this logic. If this ‘perfect experiment’ could not definitively disprove [overflow theories] theories, then what could? The subject man- ifests all the functional criteria for not being conscious of color so what would ground the claim that the subject nevertheless enjoys a special kind of consciousness: phenomenal consciousness without access consciousness

I think it is interesting to note that this kind of argument against overflow has been around for a long time. Here is a passage from Huxley’s On the Hypothesis that Animals are Automata, and Its History (from 1874),

If the spinal cord is divided in the middle of the back, for example, the skin of the feet may be cut, or pinched, or burned, or wetted with vitrol, without any sensation of touch, or of pain, arising in consciousness. So far as the man is concerned, therefore, the part of the central nervous system which lies beyond the injury is cut off from consciousness. It must be admitted, that, if any one think fit to maintain that the spinal cord below the injury is conscious, but that it is cut off from any means of making its consciousness known to the other consciousness in the brain, there is no means of driving him from his position by logic. But assuredly there is no way of proving it, and in the matter of consciousness, if anything, we may hold the rule, “De non apparentibus et de non existentibus eadem est ratio.”

The latin phrase there means something like “things that can’t be detected don’t exist.” As Huxley himself points out in the matter of consciousness, if anything, this seems correct. What sense can we make of a phenomenally conscious state that one is in no way aware of?

But it seems to me that these kinds of arguments need to deal with the mesh argument that Block defends. If the mesh argument works (I don’t think it does, at least not in favor of overflow), then we have an answer to the perfect experiment. We say that there is unaccessed consciousness in the isolated brain region because that is the (allegedly) the best over-all interpretation of the data coming in from neuroscience and psychology. Just to repeat, I DO NOT think that there is overflow but I do think that the above kinds of arguments need to deal with the mesh argument directly so I don’t find Cohen and Dnnett’s paper to advance the debate.