Dear Jo,

Thanks for your comments.

As to the elephant in the room, I am not sure that “being Joe” depends on there being cells or neurons and experiences. When all Joe’s neurons have been replaced by chips, there could still be brain events – neural representations – of  “Joe seeing a red tomato”, which would lead  the ‘zombie’ to say “I am Joe seeing a red tomato”, though the words would have no meaning for him.

I think there would be a fading, or some sort of change, in the conscious experience as the neurons involved in seeing are replaced by chips, because I think that experiences are the subjective versions of neual events. But of course this does not in my view lead to the absurdity claimed by Chalmers.

I would not agree that each cell has a sense of being Joe seeing red. Joe’s knowing that he sees red involves only the neurons which are the neural representations that he is seeing red.

Best wishes.

Anthony

The thought experiment with which my argument is dealing takes it that  Joe’s conscious experiences are different from mine: “many shades of my experience no longer present in shades of his experience.”  Indeed that is the basis of the thought experiment. Joe experiences tepid pink when I experience red. It is in this sense that I say that Joe’s experiences are different from mine. Surely one can compare two persons’ conscious experiences to this extent?

Dina,

I think that the differences in conscious experiences to which you refer occur because of equivalent differences in the brain events with which they are associated.  In the thought experiment the brain events are the same, but the conscious experiences are different because some of the neurons have been replaced by silicon chips.

The relevance of the question is to do with Chalmers’s thought experiment to support his principle that any two systems with the same fine-grained functional organization will have qualitatively identical experiences.  My argument is that the thought experiment does not support that. 

Dear Jo

The way I see it is this: in terms of the thought experiment, even though the neurons are partly or wholly replaced by chips the same brain events will occur. As you say, it should get good solid red because it will get the same set of signals. But if it is the case that only neurons in the brain of  an organic creature (and then only neurons involved in sensory perceptions or bodily feelings or images of those) can have associated conscious experiences, then the subjective experiences of Joe would diminish – fading qualias – as neurons are replaced by chips, even though the same objective brain events occur. Even though the brain is “getting good solid red,” it will gradually, in terms of the thought experiment, not continue to experience good solid red.

You explain that the only things that get signals in brains are individual neurons. But cannot those individual neurons cause effects in other neurons, so that, perhaps with effects caused by yet other neurons,  neural representations arise?  But I do not think this is relevant to  my argument.

Best wishes.

Anthony

Although we agree that the thought experiment fails to establish Chalmers’s point, I’m not sure I agree with your argument.

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Chalmers assumes a case where Joe’s brain, though some of his neurons have been replaced by chips, has exactly the same pattern of causal interaction as Fred’s, having exactly the same functional organization. So where Fred reports seeing red, Joe reports seeing red, exactly the same brain events occurring in each case, producing the same statement. It is not qualia that cause the reporting, but neural/ chip events.

But what “red” means for Joe (or Fred) depends on the conscious experiences associated with those neural/chip events (which is why I think the thought experiment fails).  For Joe “red” means what for Fred (and most people) is tepid pink, so there is no question of his realizing that he is wrong.

Dear Jo,

When a person sees something (speaking loosely), a pattern of neural firing occurs in his brain. Putting aside conscious experience, seeing the thing consists of those neural events. I don’t see why one needs to say that a single cell gets a signal – a perception consists of a number of events in the brain, involving a number of cells. The conscious experience is associated with those events – in my view being the subjective version of those events. The experience is, as it were, the neural events as they are in or for themselves, rather than as detected, recorded, measured or described from outside.

What is it that has the experience? Strictly speaking, nothing has it. Just as objectively the perception (or feeling) is a series of events occurring in the brain, the experience is simply a subjective event that occurs in the brain. But the brain comes to understand (that is to say neural structures arise which trigger thoughts or statements to the effect) that (in the case of seeing) something is happening in the person in relation to the thing seen, i.e. the person (or the self) is having an experience.  

You say there are no 'subjective experiences of Joe' to diminish because there is no 'Joe' that gets signals.  More precisely I should originally have said that experiences associated with events in Joe’s brain will diminish because experiences are only associated with neural events, not chip events. 

(As to neural representations, my suggestion is that a neural representation of a thing is a copy of the neural event (or rather combination of events) involved in seeing the thing. It represents, or stands in the place of, the thing by being able to cause in the brain what the thing would cause by being perceived.)

 Best wishes,

 Anthony.

Brian, I am persuaded by your argument.

As to your remarks on my approach to the experiment, I took simply the case of Joe in his particular state of neurons/chips.  You take the case of a being with fading qualia reporting them as remaining constant.  If the neurons which are the memories of the various previous seeings of red have been replaced by chips, then it makes no difference to what I said. If the memory neurons remain, then Joe will still say that he is seeing red, without being wrong about it for him, but he will be puzzled by the fact that he has memories of thinking that red meant  brighter colours. Rather than an absurdity supporting the principle of organizational invariance, if for example conscious experiences can only be associated with neural events, such a puzzling situation for Joe is what would happen by replacing some of his neurons with chips.

I apologise for the fact that the reference given in my original post was wrong.

It should have been 1996, The Conscious Mind, 253-63 or 1995 “Absent Qualia, Fading Qualia, Dancing Qualia” in  1995 Thomas Metzinger (ed) Conscious Experience,  

You say, “In the absence of mental telepathy there is no possible way for anyone other than Joe to know how red appears to Joe, and there is no possible way for anyone other than Fred to know how red appears to Fred.”  . Can one not at any rate say that Fred and Joe’s experiences are different, or that someone is colour blind?

You say, “The premise of the thought experiment – that one can make such comparisons – is wrong.”  The thought experiment (which of course I think comes to the wrong conclusion) supposes for argument’s sake (in order to show it leads to an absurd result) that only neurons can have conscious experiences, so that as chips are substituted for neurons Joe’s experience will fade, with the result that his experiences will differ from mine. Is that not a reasonable premise, although it involves a comparison of experiences?

Jo, I had said the experience is simply a subjective event that occurs in the brain. You ask which bit of the brain. The experience is a subjective event that occurs in the  same bits of the brain in which the relevant neural events occur.

You say, “Then the brain as a whole seems to 'come to understand' that something is happening in a person, so the person or self is having the experience. I am lost I am afraid. What if the brain misunderstands - as it almost certainly does?”  Neural events occur in the brain which constitute seeing a thing. Suppose those events occur in the brain of a baby – the seeing takes place, but obviously the baby cannot think “I am seeing a thing”. Human brains have evolved so that as he grows older and learns to speak and think, he comes to understand that he is seeing the thing.

You say, “You suggest that a representation in a brain is a set of neural events that will cause something similar to that caused by seeing the thing represented. OK. So how would these events cause something”  They would cause other neural events in the brain which might lead to muscular actions, just as the neural events involved in seeing something would do so.

You say, “Representations have to be patterns of events that have some convergent co-causal effect on at least one event. The events of the representation itself won't do because they have not yet converged causally.”  The neural events, which are the representation, are part of a chain of causation in the brain which would tend to cause the same actions as actually seeing the thing would cause .

You say, “Can you give me a candidate example of what events might be a 'themself' to have a subjective version thereof and **why** they are a themself. Why would it be only events in one head? Being a themself would not seem to be due to being connected since an event for itself is not going to be the same as its subsequent effect on another event (for itself). Being a themself cannot be a causal relation between parts. What on earth could it be?” A set of neural events occurs in one head. A conscious experience is associated with those events occurring in that head. The brain in which the neural events in question are occurring believes that the person is having the experience of seeing something. It believes it in that it has neural structures which cause it to think “I, John Smith, am seeing something”. When John Smith says or thinks that, he means the conscious experience, not the neural events.

Best wishes,

Anthony.

Brian,

Thanks for your comment. It seems then that where chips are substituted for neurons, if that system is to continue to have the same functional organization as the one where chips are not substituted, then, as chips replace neurons relevant to seeing red, the memory neurons of having seen red must be replaced by chips at the same time. If that does not occur, so Joe is puzzled by his memories of red being different, then that takes the case outside the thought experiment.  But if the chips do replace the memory neurons, so that Joe’s memories of “red” are of tepid ink, just as are what he reports as being “red”, then Chalmers can hardly claim that it is an absurdity that he cannot form an accurate judgment of his experience.

Would this be a correct statement of your argument? Chalmers’s premise is that Joe, whose neurons are gradually replaced by silicon chips, will continue to make statements about his experiences which are identical to mine, though his experiences will become different if he gradually loses consciousness as the replacements takes place. This entails that it is the neurons/chips which cause him to report on his experiences. But then to say that this is absurd because such a person would surely make a correct judgment of his experiences contradicts that, for it entails that it is experiences which cause reports about those experiences.

I think that it is neurons which cause a person to report on his experiences, but that what he means by his report is for him determined by reference to his experiences, including the experiences (mental images) associated with his memories.

Brian – I didn’t make myself clear. My final sentence entails that there would be no absurdity – the second part was the original reason I gave for that. I was just meaning to say, quite apart from the thought experiment, that my position is that it is neurons, not experiences, that cause reports of experiences.

Brian,

Chalmers’ view, as he explains it briefly (The Character of Consciousness, pp 131-2), is that “consciousness plays a role in constituting phenomenal concepts and phenomenal beliefs. A red experience plays a role in constituting a belief that one is having a red experience … If so, there is no causal difference between the experience and the belief … this immediate connection to experience and belief allows for the belief to be justified. If this is right, then epiphenominalism poses no obstacle to knowledge of consciousness.” He would then presumably not accept that to say that it is  implausible that Joe would report that he is experiencing red – because such a person would surely make a correct judgment of his experiences (and presumably report them correctly) – necessarily entails that it is experiences which cause reports about those experiences.

But this still creates a contadiction in the experiment. Red experiences have played a role in constituting a belief that I am having a red experience when I see a given object.  What about Joe?  Chalmers says that he will say that he sees “red” when in fact he is seeing  tepid pink. But according to Chalmers’s view his tepid pink experience would play a role in constituting a belief that he is seeing tepid pink Why then would not his neurons/chips involved in that belief cause him to say he is seeing tepid pink? Apparently it is beause Joe is “functionally isomorphic to me. He says all the same things about his experiences as I do about mine.” But if Joe is functionally isomorphic to me then his consciousness plays a role in constituting his phenomenal beliefs. A tepid pink experience will play a role in constituting a belief that he is having a tepid pink experience, and he will say he is seeing tepid pink, not red.

Chalmers says that conscious beings are generally capable of forming accurate judgments about their experience. Why is the part of their system that leads to that being so not part of the  fine-grained functional organization of the system, causing Joe to say that he is seeing tepid pink, not red?