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Comment by christopherolah | Hacker News Reader

It's pretty clear that your taking a scientific-materialist stance. So, my question to you is how do you explain qualia?

Qualia is a term describing the actual _feeling_ of something as consciously perceived. Wikipedia explains it better: http://en.wikipedia.org/wiki/Qualia

The problem is this: Consider perceiving the color red. An outside observer can explain this as photons hitting my eye and me reacting. The only problem is, I can actually see the color. How can a series of chemical reactions cause me to feel?

The irony of this is, of course, that pzombies (philosophical zombies: beings that don't feel anything but act exactly as though they do) would come to the same conclusion.

Since it is impossible for anyone other than myself to verify that I exist as anything more than a series of chemical reactions (ie. I actually feel), it is a difficult problem to work with.

I, for my part, was led to the conclusion that the scientific-materialist perspective was wrong, or at least grossly incomplete. It seems logical as science is essentially the art of useful fiction: we make up the simplest story that predicts the right answers and use it until it breaks (and sometimes beyond that and just avoid the points we know it breaks at).

I'm very interested in hearing others' views.

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The distinction between materialist and non-materialist is not that the non-materialist believes science is merely incomplete, as any materialist would agree with that stance; it is that he denies the very ability of science to investigate certain effects, and further, he believes those effects to be important and not mere hypothetical possibilities.

Contrast this to the materialist, who while he accepts that fundamentally there is a limit to what we can know about our universe (we're within the system, after all, and it's provably impossible to know everything about the workings of a closed system from within), still believes that we can figure out most of the important things by observing what we see around us and experimenting.

In particular the materialist doesn't think there's anything so special about humans that their workings are not completely susceptible to scientific investigation. Usually the non-materialist thinks that there's something magical happening in living creatures that makes them fundamentally opaque to observation and description.

Since it is impossible for anyone other than myself to verify that I exist as anything more than a series of chemical reactions (ie. I actually feel), it is a difficult problem to work with.

I'd argue that it's also impossible for you to verify this fact. Who's to say that you don't just think you actually feel things but in reality it's just your brain playing a trick on itself?

Taking that further (and getting into the definition problem others have mentioned), who's to say there's any difference at all between the delusion and the perception of experience?

>it is that he denies the very ability of science to investigate certain effects, and further, he believes those effects to be important and not mere hypothetical possibilities.

I'm not a materialist but I don't deny the ability of science to investigate consciousness. I think it's an open question whether or not science will shed any light on it.

I'm not sure why you think that materialism is a necessary assumption for doing science. Science is generally supposed to start free of any huge metaphysical assumptions about the nature of reality and draw its conclusions via observation and experiment. The balance of evidence might turn out to support materialism or it might not. At most, I think scientists might be entitled to assume what Russell called "neutral monism" -- the notion that there is basically only one kind of "stuff", divorced from the notion that there is anything particularly "physical" about it (whatever that means).

>I'd argue that it's also impossible for you to verify this fact. Who's to say that you don't just think you actually feel things >but in reality it's just your brain playing a trick on itself?

>Taking that further (and getting into the definition problem others have mentioned), who's to say there's any difference >at all between the delusion and the perception of experience?

Because to think such a thing way would be qualia in and of itself...

I feel that the problem you describe is exacerbated (as so many philosophical "problems" are) by the imprecision of the language used in framing the problem. Rather than bicker over word definitions, I would prefer to wait until we have computers powerful enough to simulate the brain, at which time we can answer such questions using the precise language of mathematics.

Of course I can't prove that we will be able to create such computers. If we can't then that would be evidence for a non-physical basis of consciousness. However, I feel that right now the burden of proof is on the people who claim that consciousness doesn't obey the laws of physics, as we haven't yet found any other process which doesn't.

[I am not the OP]

> I would prefer to wait until we have computers powerful enough to simulate the brain, at which time we can answer such questions using the precise language of mathematics.

I find this stance baffling. How would a complete simulation of the brain tell us how a chemical reaction could cause a feeling? That seems quite a lot to hope for!

There is also a question-begging element here. What you consider a "complete" simulation of the brain will differ depending on whether or not you are a materialist in the first place. (I.e., will the simulation include feelings as part of its model? If it doesn't, aren't you begging the question in favor of physicalism?)

>as we haven't yet found any other process which doesn't [obey the laws of physics].

Isn't this basically true by definition? If we find something that doesn't obey the laws of current physics, we just modify the laws. We certainly found processes which didn't obey the currently accepted laws of physics at a number of points in the history of physics.

Like I said, I believe the "problem" itself is ill-defined. Philosophy in general has a tendency to devolve into arguments over word definitions and I simply don't think that's productive. A simulation of the brain will give us the data we need to frame the problem precisely enough to actually answer it.

> If we find something that doesn't obey the laws of current physics, we just modify the laws.

If consciousness is truly outside the domain of science then logically there would be no law we could create to account for its effects. But I'll go a step further and say that I believe consciousness obeys the laws of physics as we currently understand them. Again I don't have a proof of this, but neither do the people who say it doesn't.

>Like I said, I believe the "problem" itself is ill-defined.

You keep saying that, but you neither specify which problem you are referring to, or in which respect you believe it to be ill-defined. So it's kind of hard to respond to a vague assertion of that sort. It's ironic that you of all people should be accusing philosophers of using language imprecisely.

>But I'll go a step further and say that I believe consciousness obeys the laws of physics as we currently understand them.

Again: what is your reason for believing this? It is not enough just to assert it. Also, you are forgetting the logical possibility that consciousness is compatible with the laws of current physics but not actually explained by them. (In the same way that, for example, the truth of the equation "2 + 2 = 4" is compatible with the truth of Newton's second law, but not explained by it because they are statements in different domains.)

The problem was stated by christopherolah, and labeled as such. I'll quote it here for your convenience:

"The problem is this: Consider perceiving the color red. An outside observer can explain this as photons hitting my eye and me reacting. The only problem is, I can actually see the color. How can a series of chemical reactions cause me to feel?"

As I have said, the respect in which it is ill-defined is the imprecise definitions of the words used. An argument about this will eventually turn to haggling over the definitions of words like "see", "perceive", and especially "feel".

"what is your reason for believing [consciousness obeys physics]?"

I don't claim to have a strong argument. This thread is already too long so I'm not going to list my reasons, but the point I'd like to make is that the opposing view doesn't have strong arguments either, and I feel the burden of proof rests more heavily on that side, considering Occam's razor.

>As I have said, the respect in which it is ill-defined is the imprecise definitions of the words used.

I don't see any lack of precision. We all know what it is like to see red, or to feel elated. The definitions of these words don't really seem to be relevant to the debate. At least in the philosophical literature on this stuff, questions of definition haven't arisen very often in the arguments between opposing camps.

>[consciousness obeys physics]

Well, to be precise, I also believe that consciousness "obeys" physics, I just don't think that the laws of physics explain or imply the existence of consciousness.

>and I feel the burden of proof rests more heavily on that side, considering Occam's razor.

Occam's razor is a device for choosing between explanations, but physicalism currently has no explanation of consciousness, so Occam's razor is inapplicable. Admittedly, none of the alternatives to physicalism give a deep or satisfying explanation for the existence of consciousness, but even a shallow explanation for the most immediate fact about our reality is better than none.

What you consider a "complete" simulation of the brain will differ depending on whether or not you are a materialist in the first place. (I.e., will the simulation include feelings as part of its model? If it doesn't, aren't you begging the question in favor of physicalism?)

Do we care? The non-materialists would argue that there's no possible way to simulate the brain completely, because of Teh Magic that surrounds it. They'll never be convinced of any model of the extra stuff because by definition Teh Magic is impossible to know anything concrete about. And the scientists will happily march right along because Teh Magic also has no actual effect on our world.

I'd argue that until proven otherwise, a simulation of the brain already incorporates Teh Magic factor, given that nobody has suggested an actual effect back on the physical world. Since a simulation of the brain is only tasked with correctly producing the mapping from inputs to the outputs that we can actually measure, all that extra stuff is already correctly factored in, with a weighting factor of exactly 0.

When we reach that point, the non-materialists are welcome to submit evidence that the factor should not be 0, but they'll need to back it up with some evidence...

If we find something that doesn't obey the laws of current physics, we just modify the laws. We certainly found processes which didn't obey the currently accepted laws of physics at a number of points in the history of physics.

Well, the difference here is that the philosophical types are not clamoring for new physical effects to be considered or anything like that, they are suggesting that the whole notion that we should be able to observe something and test it in order to theorize about it is wrong.

If anyone has any ideas about how to investigate something that you can't measure, test, or find any concrete evidence of other than people saying "Gee whiz, it sure feels like I experience something", I'd sure like to hear them.

If there was any evidence of a spin 8 1/2 "feeling field" or something like that, physicists would be all over it, and would be excitedly working out everything they could about it. But somehow I doubt that's what the "Science fails" crowd is looking for...

>Do we care? The non-materialists would argue that there's no possible way to simulate the brain completely, because of Teh Magic that surrounds it.

Right, so you are begging the question by assuming materialism in the first place. The simulation shows nothing if you do this -- it's a red herring, to disguise the fact that you are merely asserting your position without argument.

>Since a simulation of the brain is only tasked with correctly producing the mapping from inputs to the outputs that we can actually measure...

Again, isn't it obvious to you that you're begging the question here? If you irrationally deny that we can "measure" (i.e. establish) the existence of our own conscious experiences, and then refuse to incorporate any notion of experience into your simulation, you are clearly rigging the game in favor of materialism at the outset, not providing any argument for it. It is an interesting intellectual exercise, but it is not an argument for materialism.

>Well, the difference here is that the philosophical types are not clamoring for new physical effects to be considered or anything like that, they are suggesting that the whole notion that we should be able to observe something and test it in order to theorize about it is wrong.

Maybe some people are suggesting this, but you can certainly be opposed to materialism without believing this (I am, for example). It has to be said, though, that the idea that any straightforward notion of "observability" plays a role in science has been known to be highly problematic since the 20s, for basically the reasons that Quine and Duhem identified. It is in any case obvious that we can observe the existence of our own conscious experience more reliably than we can observe anything else, as Descartes pointed out.

>If anyone has any ideas about how to investigate something that you can't measure, test, or find any concrete evidence of other than people saying "Gee whiz, it sure feels like I experience something", I'd sure like to hear them.

I am observing my own conscious experience right now. We have as yet no hint of a physical explanation for why I should be having such an experience. These days, materialism seems to consist of a bunch of rhetorical tricks for denying this obvious fact (mostly centered on slandering opponents as "unscientific" because they are unwilling to jump through logical hoops to deny the obvious).

Right, so you are begging the question by assuming materialism in the first place.

Sure, you got me: "materialism" to me means "doesn't contain random bullshit that by its very definition can't even be investigated."

The moment someone offers a theory that says something concrete about any effect, it becomes "materialism." Most people pushing non-materialistic "techniques" really mean that we should throw our hands in the air and claim that we can never know how a thing works. And this is justified by claiming that modern science fails to explain mystical "effects" that nobody can even measure in a concrete way.

Put another way, suppose you're wrong, and there's no such thing as experience, and it's just an illusion of the brain that makes you believe there is - is this consistent with all of modern science? AFAIK, it is, in which case I see no justification to claim that modern science has failed.

Myself, all the evidence I've seen says that the functioning of the human brain (which is physically undistinguished, containing nothing that pushes the limits of the physics that we understand very well today) is governed by laws that we actually have a shot at understanding. I'd place good money on the fact that nothing about the brain's inner workings is influenced to any meaningful degree by any physical effect that we don't already have equations for. The only trick is understanding the large scale behavior, due to the incredible complexity.

The simulation shows nothing if you do this

Such a simulation would prove plenty - it would prove that we can approximate human behavior as accurately as we want to without including magic in the equation. You may still claim that we haven't accurately modeled the magic parts of the brain, but if they're unobservable from the outside, nobody doing anything useful really cares about the difference, and the onus is on you to prove that there is one at all, not on me to prove that there isn't.

Realize that you're claiming something extraordinary, that there is a fundamentally non-physical effect at work in the brain. This type of claim requires a lot more than a person's assertion that they experience it themselves to be credible, because people's claims about their inner states are notoriously misguided even about far less philosophical things.

If you irrationally deny that we can "measure" (i.e. establish) the existence of our own conscious experiences, and then refuse to incorporate any notion of experience into your simulation, you are clearly rigging the game in favor of materialism at the outset, not providing any argument for it.

Irrational? I disagree.

How might I "measure" the existence of subjective experience? Introspection absolutely does not measure it; rather, introspection measures my belief that I have experience, and the human brain believes a lot of things that are not true, so I can't put too much weight in that.

There's a crucial difference between the existence of a state of experience and the belief in the existence of a state of experience. I have yet to hear any coherent argument that provides evidence of the former, and the latter would be trivial for a good brain simulation to achieve.

It has to be said, though, that the idea that any straightforward notion of "observability" plays a role in science has been known to be highly problematic since the 20s, for basically the reasons that Quine and Duhem identified.

Without going too far into the details of Duhem-Quine, I'll just mention that this may bother philosophers of science, but physicists have elucidated many more useful, exploitable truths in the past four centuries by observing the world than the philosophers have over several millenia by thinking about it.

I am observing my own conscious experience right now.

Not really. What you are doing is believing that you are observing your own experience right now. That's it. Since there's no definition of "your own experience" on the table, I can't really comment on whether or not your belief that you are observing it has any correlation to the existence or non-existence of the state. But the burden of proof has to be placed on the person arguing for the introduction of a new effect, not on the person arguing against it, and I would claim that current (materialistic) theory has already adequately accounted for your belief in subjective experience.

In other words, introspection doesn't prove anything other than that you hold a particular belief. The messed up thing is, this doesn't only apply to my thoughts about your inner state, it has to apply to my thoughts about my own inner state as well; I can be no more sure that I have any extra-material subjective experience than I am that you do based on your assertion that it is so.

We have as yet no hint of a physical explanation for why I should be having such an experience.

True enough. But we have plenty of perfectly good physical explanations for why you might believe you're having such an experience, and without some other evidence that you're actually having that experience, we have to assume that the simplest and most likely explanation is that your belief is just wrong.

Just to be clear: I'm not altogether opposed to the idea that we can accept "subjective experience" as "real", for a certain definition of each term. But I do have a problem assuming that there's something that's even worth modeling or theorizing about; as best as I can figure, the most sense I can give to its reality is that it is as real as we believe it, and that the "experience" is really just the self-aware organization of information inside our brains, not some mystical interaction with an external entity or anything like that. Behaviorally speaking, both result in the same observable effects, and one requires fewer assumptions to explain the same observations, so...

Then again, Occam's Razor is another point where philosophers and scientists clash - philosophers want proof that every ludicrous possibility could not possibly be true, whereas scientists are just looking for evidence of what is actually the case, within a certain approximation. IMO the scientific POV has led to far greater successes, but YMMV.

Addition to my last post: my feelings on this particular issue (the mind-body problem, the soul, experience, or however you want to cast it) are pretty close to Hofstadter's as outlined in I Am A Strange Loop, which is a great read no matter what your stance on the issue (he doesn't take a strong stance either way, but pretty clearly indicates that he thinks it's the computation that's important, not the substrate).

I think there's something very special about perception, and it's a very deep, tricky, and important matter that we don't really understand well enough yet; however, I am agnostic towards any metaphysical details. Even if they do exist (I personally don't think there's any evidence for that anyhow, but...), I don't think there's anything much worth say about them because they are not open to investigation.

If you're agnostic regarding the metaphysical details then you're not a materialist. Materialism is a strong metaphysical position, not a form of agnosticism.

>Sure, you got me: "materialism" to me means "doesn't contain random bullshit that by its very definition can't even be investigated."

You should stop and think about that. You're essentially saying that your notion of materialism has absolutely nothing to do with any notion of "material". Isn't that kind of odd? It's certainly a long way from the materialism of the 17th century (pre-Newton) which actually had some content to it (i.e. contact mechanics).

>Realize that you're claiming something extraordinary, that there is a fundamentally non-physical effect at work in the brain.

If by non-physical I mean "not accounted for by current laws of physics", then why is this extraordinary?

>How might I "measure" the existence of subjective experience?

I think measure is just an odd verb to use in this context. How do I "measure" whether or not there is milk in the fridge? Well, I look and see. Same with my subjective experience.

>Not really. What you are doing is believing that you are observing your own experience right now.

Ok, and I'm not really seeing the desk, I'm just believing that I'm seeing the desk. Skepticism about perception is fine, but why be more skeptical about your perception of your conscious experience than of your visual or other perceptions?

The other issue here is that believing that you are having a conscious experience is itself a kind of conscious experience, so you can't really wriggle out of it that way. I might be mistaken about the object of my perceptions (ok, maybe it's not really a desk I'm seeing, or maybe I'm dreaming), but I can hardly be mistaken that I am seeing something, or that I am having a conscious experience of something.

>In other words, introspection doesn't prove anything other than that you hold a particular belief.

This obviously leads to a vicious circularity. If we can never perceive anything other than our own beliefs, then perception can provide no external ground for any of our beliefs and we must all be crazy! I just can't agree with this doctrine of yours, I'm afraid. Particularly because it would imply that scientific investigation is based on introspective observation of our own beliefs, rather than observation of the world around us -- which seems fairly anti-scientific to me.

>But we have plenty of perfectly good physical explanations for why you might believe you're having such an experience

In fact we do not. At least, I have never seen one. Do you have a reference? In this area, people often confuse a sketch of what an explanation might look like with an actual explanation.

>and that the "experience" is really just the self-aware organization of information inside our brains, not some mystical interaction with an external entity or anything like that.

I would mostly agree with that. But I'd just point out how we currently have no physical explanation of how a self-aware organization of information could lead to a conscious experience. You are cheating a bit by introducing the term "aware', which of course could not be stated in purely physical or mathematical terms while retaining its normal connotations.

>Behaviorally speaking, both result in the same observable effects

Again, only because you irrationally (and frankly, insincerely) insist on denying that you have conscious experiences. Or admit that you have them but say I'm not allowed to consider this fact in my reasoning. I'm not sure which.

>philosophers want proof that every ludicrous possibility could not possibly be true

This is just not true. Philosophers aren't like that at all, and I don't see any great divide between scientists and philosophers over this issue. Both are taking a scientific point of view.

qualia has a physical description: simply describe a brain the moment that it is receiving sense data of light in the red spectrum.

that this is currently beyond us technologically doesn't mean that it is in any way a philosophical conundrum.

There's a difference between describing the brain receiving data and describing me seeing red. I don't experience myself as a brain, and I certainly don't experience "receiving data", so your description of these things would not be of things I experience when I see red.

sure it is, simply make it your brain that we describe and it will be you seeing red. the brain being described doesn't experience itself as a brain...so what?

It's the difference between describing how something works and describing what something's like to the person doing whatever it is you're describing. Science can (arguably) get at how something works, or at least make some predictions and models concerning these things, but that's not the same as getting at what something's like, from a "subjective" standpoint.

Scientists can ask me about what the experience of "red" is like, and I can tell them that it's not quite like blue or green, and can point to it, but the experience itself (like all experience) remains a completely private matter for me.

Just think about it. Look at any red object and compare it with any "scientific" description regarding wavelengths and retinas, neurons, synapses, neurotransmitters, visual cortexes, atoms, molecules, or what have you. Clearly none of these thing are in any way related to what it's actually like for you to see that red object.

Now, you may well believe that what's going on when you look at a red object is "really" some interaction between what those scientific terms describe in some model of what's going on with your brain, sensory organs, etc. But this requires a sort of suspension of disbelief, as you have to set aside your actual "subjective" experience of the red object itself (an experience which lacks the mediation of all these scientific terms, models, or even what they refer to, as you don't experience the neurons, or retinas, or neurotransmitters, as such, you just see the red object).

The subjective experience is really where science is quite helpless. It's been this way for hundreds if not thousands of years, and there's no sign it's getting any closer now.

Most emphatically, no. Well, I suppose yes, for now, but that's only because your complete brain state is effectively hidden from the scientist because we don't have the technology to get a good picture of what's going on inside. Give us a decent real time high resolution scanner, and your "private" experience is just another data set on a big computer somewhere.

A C++ program would be pretty damn inscrutable, too, if we couldn't core dump when things went wrong...

Look at any red object and compare it with any "scientific" description regarding wavelengths and retinas, neurons, synapses, neurotransmitters, visual cortexes, atoms, molecules, or what have you. Clearly none of these thing are in any way related to what it's actually like for you to see that red object.

Look at any Youtube video and compare it with the "computer science" description, with bits and bytes and encodings, filtered through the Flash player, etc. One could argue that these things are clearly unrelated to some kid getting whacked in the nuts by his brother, but one would be wrong.

I'm extremely reluctant to accept the notion that our physical brains have no relation to how we experience the world (an idea you seem eager to accept) - we don't understand it very well, true, but that's partially because we're pretty stupid, and partially because we're not very far along in understanding it yet.

All that it takes for you to claim subjective experience is for your brain to be programmed to respond to the question "Do you have subjective experience of the color red?" in the affirmative. To me, that's a lot easier to swallow that that's the case than to imagine there's Magic going on here...and yup, I'm happy to apply the same logic to my own experience, I don't attribute anything special to it other than a mere self-reinforcing computational delusion.

Personally, I find that a far more fascinating thing than the alternative, anyways...

It really doesn't, though, unless you already ascribe something mystical and aphysical to this "subjective experience," begging the question.

Someone else brought up the idea of a pzombie, someone that responds in every way as if they had subjective experience, but really doesn't. Getting past WTF that would actually mean, since nobody ever bothers to define "subjective experience," I think the heart of the question is this: if a pzombie responds internally as if it had subjective experience as well as externally, then isn't that enough for us to say that it does? That's why I'm happy to write the whole thing off as a non-issue, even when thinking about my own experience - the fact that I believe I experience "red" means nothing more than that I believe it.

IMO anyone arguing against that first has to figure out what it means for a pzombie to lack subjective experience even though it looks, walks, talks, acts, and thinks as if it did. Otherwise the argument is pretty pointless, kind of like asking what the world would be like if the prime number theorem was false.

>Give us a decent real time high resolution scanner, and your "private" experience is just another data set on a big computer somewhere.

That huge dataset still won't tell you what it's like to see red, though. It will just tell you what happens in the brain when someone sees red.

>It really doesn't, though, unless you already ascribe something mystical and aphysical to this "subjective experience," begging the question.

You don't have to do anything of the sort. You just note that there's nothing in the physical description which corresponds to the subjective quality of your experience. To make it more concrete, there's nothing that explains why seeing red isn't like seeing blue and vice versa.

constantly asserting that "it just isn't" does nothing for your case. hypothesis must be differentiable via making different predictions about the world. otherwise they're not really different.

(I'm not parent, I'm the one who originally asked the question.)

Certainly, a _scientific theory_ is judged based on its predictive power. This is why I mentioned my opinion, earlier, that science is "the art of useful fiction." The goal isn't to achieve truth but to predict.

Philosophy, on the other hand, is concerned with what is _really_ true, not predictions.

Certainly, the experience of qualia has no effect demonstrable to an outside observer. That doesn't make it any more or less real. I experience, therefore it must exist. I merely can't prove it to you. The great thing is that you can prove it to yourself. All you have to do is pause for a moment and rationally examine what you feel.

If your interested in an attempt to explain it from a materialist perspective, you may wish to look at Roger Penrose _The Emperor's New Mind_. He argues that consciousness is intricately tied to QM. Or at least I think he does... It's difficult reading and I haven't read the whole thing yet!

It's on Google Books, here: http://books.google.ca/books?id=oI0grArWHUMC&dq=The+Empe...

The first chapter provides an excellent explanation of qualia.

what is _really_ true IS what makes the best predictions. Otherwise in what sense is it true? Qualia has no effect demonstrable to an inside observer because you have no other data points to compare to. You have only one data point: your own consciousness.

>what is _really_ true IS what makes the best predictions. Otherwise in what sense is it true?

That is the anti-realist position, but it could be true in the sense that it corresponds to the actual nature of reality, if you are a realist.

> You have only one data point: your own consciousness.

Yep, and that is the data point that physicalism doesn't seem to be able to account for.

you're covering it up with the term "actual" what does that mean?

your second assertion doesn't make any sense either. "account" would imply that pzombies would be different from "normal" normal people I guess?

No, you could delete "actual" and it would still convey the right sense.

Yes, p-zombies are different from normal people (by definition).

Neither will saying "it just does." How do you think that seeing a detailed brain scan would tell you what it is like to see red? It's extraordinary that you think the burden of proof is on those who simply deny the near-inconceivable possibility that it would.

The problem is precisely one of predictions. Physicalism doesn't predict the existence of conscious experience. (And if you really think its necessary to give an argument for the existence of these experiences other than "we all have them and know that we have them," I am not sure what to say -- you are simply in denial.)

Physicalism doesn't predict the existence of conscious experience. (And if you really think its necessary to give an argument for the existence of these experiences other than "we all have them and know that we have them," I am not sure what to say -- you are simply in denial.)

It is absolutely necessary to give an argument for the existence of these experiences.

I know that you believe you have them, and that I believe I have them, but that doesn't mean that they have any tangible reality, it just means that our brains store things in a way that they will respond "yes, I have conscious experience."

Alternatively, should I accept as real everything that a person believes they experience? A schizophrenic's voices are real? A memory of a past trauma that is, in fact, a false memory, proves that the past trauma is real? This is a very dangerous path to walk, accepting the validity of introspection as a means of investigating the world...

>I know that you believe you have them, and that I believe I have them, but that doesn't mean that they have any tangible reality

It does in the case of experiences. I can't even conceive of what it would mean to be mistaken about the very fact that you are having experiences. It would be a very different sort of mistake from that of being mistaken about the _object_ of an experience (thinking that you are hearing voices when there aren't any, etc. etc.)

Also, your use of the word "tangible" is very odd in this context. Almost by definition, nothing could be more tangible than an experience.

>[I know that] I believe I have them

So, do you believe that you have them or not?

the burden of proof clearly lies with those who posit the existence of an unobservable quality to cognition.

I'm not positing the existence of an unobservable quality to cognition. What gives you that idea?

I just reread the first chapter of Penrose's _The Emperor's New Mind_ so this is based off of it.

Let's simplify the problem to just conversation, for the sake of simplicity. Suppose we have a program that can pass the Turing test... But the way it is constructing it's responses is only a more capable version of the emacs psychiatrist. Does it have consciousness?

I posted a link to ENM in another post. Maybe look at the first chapter. It hits the nail on the head, IMHO.

EDIT: Or even just read the first few pages... It seems to introduce it decently, if your short on time.

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