An experience is not a concrete thing like cups and taste buds are. It instead describes your practical contact with things in the environment, which occurred at some time and location.
— Andrew M

1. Isn't the "practical" (physical?) contact between you and your environment a "concrete thing"?
— Luke

No, it's an abstraction over concrete things. It describes something that a person does or has. That is, no person, no experience. (Which we can appreciate if we substituted a robot for the person, since robots don't have experiences.) — Andrew M

I was probably unclear. You said that an experience "describes your practical contact with things in the environment". Could you clarify whether "practical contact" is the same as "physical contact"? If so, isn't one's physical contact with the environment a concrete (i.e. physical) thing? (This would imply that an experience is a physical thing.)

2. Isn't there more to an "experience" than this physical contact? E.g. There's not just the "practical contact" experience of light entering the eye, there's also the experience of seeing red.
— Luke

Those aren't experiences, at least on an ordinary definition. This is a good example of how we're using language in completely different ways. — Andrew M

Seeing red is not an experience? To be clear, I'm talking about a person seeing red (e.g. seeing a red object).

Experience isn't merely physical contact. A robot can do physical contact. But it isn't therefore something separate from physical contact either (which would be dualism). It's an abstraction over that physical contact in a manner applicable to human beings. — Andrew M

I'm not sure that I understand. You're saying it's not merely physical contact but it's also no more than physical contact...? How are robots any different in this regard?

And I would add that the practical contact is between the cup/coffee and the person, not between the person's eyes and the photons. The latter is detail about the physical process and operates at a different level of abstraction than what I'm describing here. — Andrew M

On the one hand, there is practical contact between a person and a coffee. On the other hand, there is practical contact between a person and photons. What's the difference? What other process is there besides "the physical process"?

It doesn't require any special definition.
— Luke

You've been on this site for a while now. Is your impression that we're unanimous? — Kenosha Kid

What are you on about? If you disagree with the Wikipedia definition of "mind" that I quoted, feel free to spell out where you disagree.

If you don't want to explain what you meant by "in principle" or to discuss it further, that's fine.

Ah. If you read a bit further down, I point out that there are many things we cannot observe directly (such as quarks, Higgs bosons, spacetime curvature) but rather through their effects. — Kenosha Kid

Doesn't empirical verification require direct observation? Otherwise, it's indirect observation and inference.

I had assumed that when you said "The physical...is that which is empirically verifiable in principle by definition," that the "in principle" meant something like "with sufficient technology", whereby we could directly observe the physical. Otherwise, what did you mean by "in principle"?

Really, all observed things are detected by their effects. — Kenosha Kid

Perhaps, but there's a difference between directly seeing/perceiving something and seeing/perceiving only its effects. Empirical verification has to do with direct observation via the senses.

So there are two possibilities here: 1) the mind is not detectable directly or indirectly, in which case we have no justification for claiming it exists; 2) it falls under the purview of physicalism. — Kenosha Kid

Or 3) minds do exist, but because they cannot be empirically verified - even with sufficient technology - then they are not physical (according to your definition).

A simple (to write down) verification would be to choose something that the mind does, take a sample of people, and test whether that property is present. What that is will greatly depend on how you define 'mind'. — Kenosha Kid

It doesn't require any special definition. Wikipedia offers the following, which seems suitable enough:

The mind is the set of faculties including cognitive aspects such as consciousness, imagination, perception, thinking, intelligence, judgement, language and memory, as well as noncognitive aspects such as emotion and instinct. — Wikipedia

I was responding to your statement that “The physical...is that which is empirically verifiable in principle by definition.”
I’m asking how do you verify a mind or mental states?

The physical (as in physicalism, as in the physical sciences) is that which is empirically verifiable in principle by definition. — Kenosha Kid

What about the distinction between mind/matter or mental/physical? Is there such a distinction, or do minds/mental states not exist?

There's not just the "practical contact" experience of light entering the eye, there's also the experience of seeing red. — Luke

Yes, and that experience happens inside the brain. — Marchesk

Perhaps, but that doesn't explain (away) the duality of the experience.

An experience is not a concrete thing like cups and taste buds are. It instead describes your practical contact with things in the environment, which occurred at some time and location. — Andrew M

1. Isn't the "practical" (physical?) contact between you and your environment a "concrete thing"?
2. Isn't there more to an "experience" than this physical contact? E.g. There's not just the "practical contact" experience of light entering the eye, there's also the experience of seeing red.

So when you say "I feel angry, so there must be such a thing as 'anger'", what is it you're committing to the existence of? — Isaac

The feeling.

A sufferer might say "I'm in pain, I think there's something stabbing inside my thigh and it's shooting down my leg". The doctor will carry out a series of examinations. On finding no nerve or tissue damage in the thigh he might think about referred back pain. We take no issue with him saying something like "I know it feels like there's something stabbing inside your thigh, but there isn't, you're mistaken. What's actually happening is that you have some tissue damage in your back". Or, if he finds no damage there he might consider the pain neuropathic, or even (worst case) made up entirely. Either way, we consider his knowledge of physiology to trump our gut feeling about the cause. — Isaac

"I'm in pain" is not a causal explanation (a causal explanation for what, the pain?). Saying that you feel a stabbing pain in the thigh is an expression of the pain, not an attempt to explain its cause. You expect the doctor to tell you what the cause is.

Why would you assume privileged and accurate access to your mental states when you already know you have no such privilege over your bodily states? — Isaac

Maybe the doctor should be telling the patient how their pain feels? Why does the doctor need any verbal cues at all to know what the ailment of "the sufferer" is?

The phenomenological end result is the thing we're taking seriously (the feeling of pain in the thigh, the feeling of anger), not the phenomenological 'gut feeling' about how such a result came about. — Isaac

You're taking it seriously? I thought you wanted to "quine" it.

We're not going to get anywhere in his stated project if you just insist that whatever you feel is happening is what's actually happening. — Isaac

It depends what you mean by "happening". Qualia proponents might insist that however it seems or feels is no more than how it seems or feels, regardless of "what's actually happening". The latter seems to be an attempt to force the discussion into neurological/behavioural terms.

In order to map brain states to phenomenological reports, you have to accept what neuroscientists are saying about brain states, otherwise you're saying phenomenological reports are infallible in a way the neuroscience isn't. — Isaac

Why do neuroscientists need to rely on the phenomenological reports of subjects? Why don't they study the phenomenological states of subjects instead?

It could equally be said: In order to map brain states to phenomenological reports, neuroscientists have to accept what subjects are reporting about their phenomenological states (to some degree), otherwise you're saying neuroscience is infallible in a way the phenomenological reports aren't.

So neuroscience says there is not an identifiable neural correlate for anger - we've looked really hard and can't find one. You've two choices 1) insist that because it feels like there must be one to you then that's the case and neuroscience just isn't trying hard enough, or 2) accept that something feeling like it's the case is not necessarily proof that it is, in fact, the case and work out how those feelings might have come about. — Isaac

There's no anger, but there's still these unexplained "feelings" that people continue to call 'anger'? And since neuroscience can find no neural correlate for 'anger' then the feelings must be wrong? Jesus.

And your position is that qualia exist (are a coherent ontological commitment), so saying their existence is 'obvious' is exactly the same as saying that your position is obvious. It's no different to arguing that 'Elan Vitale' is obvious, or that 'Aether' is obvious. — Isaac

The way the world seems is not a theory, is it? To try and put it another way, the biological machinery produces some end-product of consciousness, and that end-product is not theoretical, is it? It's a real end-product.

It doesn't matter what weird expression you use, they all end up empty. "What it's like...", "the way it seems...", "how it feels"...none of these expressions have any coherent meaning beyond behaviours and interoception of physiological states. There's nothing they describe that the aforementioned don't. — Isaac

With your last sentence it sounds like you accept that we have qualia but that you want to provide a physical explanation for them. I'm fine with that. It's your rejection of qualia (the end-product) that I don't understand.

But hey, it's my thread, so keep adding to it. — Banno

Do I need your permission?

Simply claiming your position to be 'obvious' is a lame argument. Do you really expect anyone to take that seriously? — Isaac

I never said that my "position" was obvious. I said that qualia are obvious. The definition of obvious is "apparent", "perceptible", "self-evident". Qualia are - according to Dennett - "the way things seem to us". So yeah, qualia are obvious, obviously.

What I should have said is Witt is using its impossibility; as I did say, using it as a fact — Antony Nickles

On your reading, he's using the impossibility as a fact. Okay.

My argument is that this is not being used as a conditional statement — Antony Nickles

How can it be otherwise? Lions can't talk.

If he is asking us to imagine something, what sense do the sentences around it make? — Antony Nickles

I don't think it's clear, but I'm not sold on your reading. At least, not yet.

To All:

You can't tell us what qualia are, because they are ineffable.

And you cannot show them to us what they are, because they are private.

Were this any other argument, you would join us in rejecting them. — Banno

If you don't know how (an instance of seeing) the colour red looks to you or how (an instance of having) pain feels to you, then there's little to discuss here and I'm surprised that you can make any sense of Dennett's paper.

...all you have done is engage in the circular argument that the biological machinery cannot tell us about the qualia, and the qualia are what the biological machinery cannot tell us about. — Banno

The constant refrain of the idealist.
"X is not amenable to empirical evidence from the material world of the physical sciences" - before proceeding to expound exactly how an understanding of X should impact our behaviour in the aforementioned material world. — Isaac

Ohhhh I see. All this feigned ignorance of seeing colours, tasting tea and feeling pain is done in the service of maintaining physicalism. Admitting the obvious might upset the physicalism gods.

"I cannot know what is going on in him"

"We could not understand a lion if it talked."

The first is a refusal, the second is an impossibility. — Antony Nickles

I'm not sure what you mean by an impossibility. Is it impossible that lions can talk? Yes, but Wittgenstein is getting us to imagine that a lion could talk, and given that case we could still not understand it. Is it impossible that we could not understand a lion if it talked? It's a conditional statement and hardly a self-evident fact. Why do you consider it such a straightforward fact that it would be impossible to understand a lion if it talked? Would it speak English or Lion?

Is there (do you have) another way (attempt) to account for all of this evidence? — Antony Nickles

I'm reluctant to get into it because I find it so enigmatic, but I might side with the quote from your OP: "because our context of 'understanding' is so radically different than that of a different species".

I will also say that it is illustrative of Witt's method of looking at the use of language — Antony Nickles

I agree that W is attempting to "turn our whole inquiry around" (PI108).

If you want to be able to fix words or speech to something inside the brain (ideas, thoughts, mental occurrences; what has been termed 'qualia') then hanging onto that makes it hard to shift to seeing the motivation for that, which Witt is pointing out. — Antony Nickles

Where does he talk about "fixing words or speech to something inside the brain"? I don't find the relationship between mind and body to be an immediately apparent goal of his investigations.

So some, out of the same desire, have latched onto his term of Forms of Life, as a communal agreement, or a type of rule, that ensures the meaning of words. — Antony Nickles

It sounds as though you take this to be a misunderstanding of Forms of Life. If so, what do you understand "Forms of Life" to mean or to be about?

Also, do you think Wittgenstein uses the terms "know" and "understand" synonymously?
— Luke

After looking around in the book, I would say, sometimes its close, but not here. As with most words, the 'grammar' of the word allows for many senses (and for new ones). Knows, as: has knowledge; as: acknowledges; as: familiar with; as: know how to continue, etc. Understands, as: understands how to (do a procedure); as: commiserates with (a person); as: can follow (what someone is saying, their point), etc. — Antony Nickles

If these terms are not synonymous, then doesn't this create a problem for your reading of:

"I cannot know what is going on in him"; and

"We could not understand a lion if it talked"?

Doesn't it loosen the connection you are wanting to draw between these?

The use of this statement is as a fact, to be contrasted with the conviction, or the strangeness of traditions... But, yes, this is simply meant to be an uncontested fact, used for comparison. — Antony Nickles

I think you need to provide more support for this reading. Why couldn't it be another example of "the convincing expression of a conviction"? Or something else? Wittgenstein isn't the easiest philosopher to get a handle on and "if a lion could talk" is one of his more enigmatic statements. Your reading may be correct but I don't yet follow why it is, or what you're trying to say exactly. I'm also curious about the other parts of your discussion title re: qualia and forms of life which you said little about in your OP.

" 'I cannot know what is going on in him' is above all a picture. It is the convincing expression of a conviction. It does not give the reasons for the conviction. They are not readily accessible."

The "cannot" here I strongly impress upon you to find a way to see is in contrast to the "could not" in the lion sentence. ("If a lion could talk, we could not understand him.")

As in (placing the phrasing in parallel structure): 'Now HERE [with the lion] we COULD NOT understand him'--as in, it is impossible, a fact (see ** below)--but with the person saying they 'CANNOT know' another person, this is a conviction--a decision or firm belief. [The ’quotes’ are only a re-phrasing of Witt.]

And so we CAN (as opposed to the lion) know what is “going on in him” (though see *** below), and saying we cannot is a conviction, a belief (in this example, in a particular picture; roughly, that meaning is tied to an idea). Apart from just the conviction in the picture though, Witt is making a point that we are responsible in how we treat the other. It is an ethical argument, not (merely) an epistemological one. The conviction is a person's choice not to ACCEPT what is going on in the other, as opposed to how it would be with the lion, where we simply can NOT understand there (it is a fact, not a choice). — Antony Nickles

Are you saying that it is a person's (ethical?) choice not to understand a lion? Or are you saying that it is impossible to understand a lion (as "a fact, not a choice")? It seems to be the latter. Couldn't we make a choice to try and understand a lion?

Also, do you think Wittgenstein uses the terms "know" and "understand" synonymously?

Learning what pain is consists in no more than being able to use the word suitably. — Banno

Learning any concept consists in no more than being able to use the word suitably. However, it does not follow that pain consists in no more than being able to use the word "pain" suitably.

Likewise, learning what a tree is consists in no more than being able to use the word "tree" suitably. However, it does does not follow that a tree consists in no more than being able to use the word "tree" suitably.

There is a distinction between "pain" and "learning what pain is".

"How do you teach someone what pain is" assumes that there is some thing that is had in common by a scratch, a broken arm, a bowl perforation, a broken heart, a betrayal; and of course this is wrong.

All that red things have in common is that we use the same word for them.

All that pains have in common is that we use the same word for them. — Banno

All that games have in common is that we use the same word for them? Wittgenstein's point is that family resemblance concepts have no essential defining property, not that they have "no sense or referent".

Rather, it's that "'pain' does not refer". At least, not in the same way that "apple" does. — Banno

What does it mean for a word to refer "in the same way" as another word? Why should we expect all words to refer "in the same way"? If a word does not refer "in the same way" as another word, does it imply that one (or both) of the words must have no referent?

How can something have a bitter taste if taste is only a concept? — Luke

By associating the concept with it. That's what 'having a bitter taste' means. — Isaac

You said earlier that taste was a concept:

The taste is a public concept. The experience is a unique set of memories, emotions, desires, sematic associations etc resulting from the taste. — Isaac

Now you're saying instead that (a bitter) taste is "associating the concept with it". What is "it"?

I'm not sure what bearing you're expecting the fact that you 'would have thought' taste experiences result from eating or drinking to have on the matter. — Isaac

I'm sure you're right; taste is only a concept and has nothing to do with eating or drinking.

Whether something is 'bitter' and what 'bitter' means are two different things. we might all agree what 'interesting' means, that doesn't mean we all agree on what things are 'interesting'. — Isaac

According to what you've said, whether something is 'bitter' cannot be different from what 'bitter' means. How can something have a bitter taste if taste is only a concept? How can a concept be bitter?

The taste is a public concept. The experience is a unique set of memories, emotions, desires, sematic associations etc resulting from the taste. — Isaac

Wow - all that results from a public concept? — Luke

Yes. Is there some limit you had in mind to the number of things a public concept can be party to? — Isaac

Being "party to" is one thing. You've suggested that a taste experience is "a unique set of memories, emotions, desires, sematic associations etc" that results from a public concept. I would have thought that a taste experience resulted from eating or drinking instead.

I can't possibly think one thing is 'sweet' whilst other people think a different thing is 'sweet', otherwise there's no public meaning of 'sweet' for us to use and the word ceases to have any function. I might be able to detect sweetness in something that other people cannot, but what sweetness is must be public. — Isaac

"phenol-thio-urea., a substance which tastes very bitter to three-fourths of humanity, and as tasteless as water to the rest. Is it bitter?" — Luke

How do you know phenol-thio-urea is a substance which tastes very bitter to three-fourths of humanity, and as tasteless as water to the rest if we don't have a public meaning for 'bitter'? — Isaac

You've missed the point. You said that you "can't possibly think something is 'sweet' while other people think a different thing is 'sweet'. That is, you implied that we must all agree on what is 'sweet'. However, the example of phenolthiourea that Dennett gives shows that not everyone agrees that it is 'bitter'. How do you reconcile this with your claim that everyone agrees on what is 'bitter' (or 'sweet')? Are they disagreeing over the meaning of the word?

Why must it come down to a matter of ability? — Luke

Public meaning. If it weren't public concepts and our ability to detect them, then we'd have nothing to speak of and would never have learnt the term for the concept in the first place. — Isaac

How do we "detect" public concepts? I thought we just learned to use them.

So why does it seem like we see colours? — Luke

Because there's a public word for them. We're there no word, you'd be less likely to think you see colours. — Isaac

Your position is that we don't really see colours, it only seems like we do because of our language? Then how and/or why did the English-speaking community come up with these concepts?

So color-blindness implies a kind of privacy in practice - they can't make the color distinctions that normally-sighted people can. But that is a practical problem, not a philosophical problem. — Andrew M

What is the difference between practical privacy and philosophical privacy?

Because you seem to be invoking privacy even between normally-sighted people. — Andrew M

I await your distinction between practical privacy and philosophical privacy. Either way, I don't think you've addressed the privacy issue that I noted previously:

"You can't perceive or experience another person's perceptions and experiences. That's just a fact of being you and not them."

The Wikipedia article on Qualia gives the following definition of privacy: "all interpersonal comparisons of qualia are systematically impossible."

Because you seem to be invoking privacy even between normally-sighted people. That would be true if there were an intermediary (phenomenal) layer between the person and the world that they are perceiving. That intermediary layer is what I'm rejecting.

Now a color-blind person's experience is different to a normal-sighted person. But there is no intermediary layer for them either. — Andrew M

If the difference between a normal-sighted person and a colour-blind person is not in their supposed "phenomenal layer", then how are they different? Why does colour-blindness involve a practical privacy but normal-sightedness doesn't?

By all means, I wish someone would at least offer some sort of explanation for using these words. If it's useful for picking out or emphasizing the subjective, phenomenal aspects of experience, then surely one of the proponents would utilize the tool by doing so.

Which aspects exactly? — creativesoul

How colours appear to each of us, for starters, e.g. what a colour in the chart above "looks like" to you.

How do you know that what I experience (colour-wise) when I see a red cup is the same as what you experience (colour-wise) when you see a red cup?
— Luke

I do not. Nor need I. — creativesoul

But you claimed that you do know. You've claimed, and are continuing to claim - without any argument - that red objects must appear the same to everyone.

“Since we both learned color words by being shown public colored objects, our verbal behavior will match even if we experience entirely different subjective colors.”
— Luke

Those entirely different subjective colors are always like the little man who wasn't there. — creativesoul

How so?

They're quite clearly not entirely different. — creativesoul

Why not? Do you have any supporting argument?

We all pick out the red ones. — creativesoul

But that's the point of inverted spectra: "our verbal behavior will match even if we experience entirely different subjective colors". We should expect to find that we would succeed in picking out "red ones" even if colours appeared to each of us differently, because we each learned to associate the colour words with however that colour appears to us (regardless of whether the colour appears the same to everyone else). Merely repeating that we succeed in picking out red cups is not an adequate response.

Does that appear red to you?

Yep.

Cool. — creativesoul

“Since we both learned color words by being shown public colored objects, our verbal behavior will match even if we experience entirely different subjective colors.”

Red, I would think. — creativesoul

You’re not certain? You said that “we do sometimes know what others are experiencing when seeing a red cup”. How do you know that what I experience (colour-wise) when I see a red cup is the same as what you experience (colour-wise) when you see a red cup?

Has something to do with the visible light spectrum that they're picking out. — creativesoul

What is this “something “?

,

We all know what red cups look like. We know that each and every experience of seeing a red cup always involves seeing red cups. It only follows that we do sometimes know what others are experiencing when seeing a red cup for we know that the experience - most definitely - includes red cups. — creativesoul

You might know how red objects appear to you (or what red objects “look like” to you), but how do you know how red objects appear to other people? How can you know that red objects appear the same (colour) to everyone?

No one has yet shown why the idea is indispensable, so why bother with it — Janus

I find the argument that we should eliminate synonyms to be an unusual one. The term qualia seems to be useful in philosophy of mind discussions to pick out or emphasise the subjective, phenomenal aspects of experience. We can talk of the experience of skydiving or of playing the piano without necessarily focussing on these aspects. The concept might also be considered useful particularly given that some people try to eliminate such aspects as illusory. We could use the terms ‘experience’ or ‘perception’ instead, as long as we restrict such talk to referring only to the subjective, phenomenal nature of the experience or perception (although ‘perception’ might be a closer synonym that doesn’t require the qualification). But then we could more easily just refer to qualia instead.

Feelings and experiences vary widely. For example, I run my fingers over sandpaper, smell a skunk, feel a sharp pain in my finger, seem to see bright purple, become extremely angry. In each of these cases, I am the subject of a mental state with a very distinctive subjective character. There is something it is like for me to undergo each state, some phenomenology that it has. Philosophers often use the term ‘qualia’ (singular ‘quale’) to refer to the introspectively accessible, phenomenal aspects of our mental lives. — SEP

In philosophy and certain models of psychology, qualia (/ˈkwɑːliə/ or /ˈkweɪliə/; singular form: quale) are defined as individual instances of subjective, conscious experience. The term qualia derives from the Latin neuter plural form (qualia) of the Latin adjective quālis (Latin pronunciation: [ˈkʷaːlɪs]) meaning "of what sort" or "of what kind" in a specific instance, such as "what it is like to taste a specific apple, this particular apple now".

Examples of qualia include the perceived sensation of pain of a headache, the taste of wine, as well as the redness of an evening sky. — Wikipedia

The felt or phenomenal qualities associated with experiences, such as the feeling of a pain, or the hearing of a sound, or the viewing of a colour. — The Oxford Dictionary of Philosophy

Qualia emphasises the subjective, phenomenal, felt aspects of experience.

What you meant by “extra layer” was “potentially confusing synonym”?

Nothing problematic about experiences. Why do we need the extra layer of "qualia", though? — Janus

Why does it need to be an “extra layer” though?

Are you not just saying that the mental/experiential are not perceptible material objects? — Janus

Pretty much. This seems to be what divides existing things into the physical and mental categories.

Life itself is not a perceptible material object; would it follow that life is not physical? — Janus

That's a good question. I'm not sure if it's a satisfactory answer, but if life is defined as a distinction between organic and inorganic matter, then life is a category of matter, and so life is physical in that sense. It's the matter that's perceptible, regardless of whether it's organic or inorganic.

Yes, but doesn't it "occur concurrently" only by virtue of having originally emerged or evolved, both in the individual's and the species' cases? I mean you were a zygote before you were conscious, no? — Janus

Yes, "emergence" in the concurrent sense where mind emerges from brain function could have come about via "emergence" in the evolutionary (non-concurrent) sense. I just think that we should avoid any conflation of these two different meanings of "emergence".

Perhaps they have been dissolved to the satisfaction of some.Whether or not someone thinks they have been dissolved seems to be a function of the person's presuppositions — Janus

Fair enough, and perhaps they have not been dissolved to the satisfaction of others.

Because you're describing your perceptions and experiences as private and inaccessible to others. — Andrew M

But you appear to speak the same way. At least, you don't speak with certainty that colours do appear the same way to both of us. The way colours appear to each of us is not public, is it? If it were public, then there would be no doubt about the (im)possibility of inverted spectra. If it were public, then we could directly see how colours appear to those who are blind, colour-blind, short-sighted, synaesthetic, etc. This doubt and lack of public access doesn't require a Cartesian theatre. If you allow for the possibility that colours can appear to some/each of us differently, then you must also allow for what you consider to be a Cartesian theatre. However, I don't think it's required. You can't perceive or experience another person's perceptions and experiences. That's just a fact of being you and not them.

Or maybe you have normal color vision and perceive it the same as me. Do you agree that that is a possibility? — Andrew M

Yes, I do consider it as a possibility. Do you consider it a possibility that there could be differences in our colour vision (yours and mine), however slight?

If you do, then we have a case where not only are we both seeing a red apple, but the apple also appears red to both of us.

If that condition is met, we have a common reference point in the world that we can use language to talk about. — Andrew M

We don't need to meet the condition of "the apple appears red to both of us" in order for us to use the word "red". How red appears to you does not need to be the same as how red appears to me in order for us both to use the word "red" the same way. That's the point of the inverted spectra intuition pump. (The colour-blind are more easily discoverable because of their inability to distinguish between colours e.g. red and green.)

So how does this model deal with disagreements about what is perceived? Via norms that function much like the standard meter length bar that used to be held in Paris. If you want to check whether the apple is red, find a normally-sighted person and ask them. — Andrew M

But, again, if how the colour of the apple appears to a normally-sighted person was public (and not private), then we shouldn't need to ask them in order to find out.

Your reference to "how the colour...appears to a...person" is all that I mean by qualia, so why do you get to avoid "the Cartesian theatre model of perception" but I don't?

If the Cartesian perceptual model is rejected, then the simple answer is that we don't have "phenomenal" experiences at all (i.e., there is no experience of an "inner" egg), we just have ordinary, everyday experiences involving ordinary, everyday things like red apples. — Andrew M

What's the difference between phenomenal experiences and "how the colour...appears to a...person"?

The taste is a public concept. The experience is a unique set of memories, emotions, desires, sematic associations etc resulting from the taste. — Isaac

Wow - all that results from a public concept?

I don't understand the process you're suggesting here. — Isaac

You said: "I can't possibly think one thing is 'sweet' whilst other people think a different thing is 'sweet'"

Intuition pump #10 says: "phenol-thio-urea., a substance which tastes very bitter to three-fourths of humanity, and as tasteless as water to the rest. Is it bitter?"

I might think the coffee is bitter, you might think it less so, but 'bitter' is a public concept, we're both talking about the same thing. What's different is our ability to detect it in the coffee. — Isaac

Why must it come down to a matter of ability?

No, our spectra could not possibly be inverted. — Isaac

Sure, not if we don't see colours.

Receptors in the retina sens trichromous signals to the retinal basal ganglia. These are combined in the V1 area of the occipital cortex to form signals responsive to combinations of wavelengths, different combinations will (normally) fire different neurons (or fuzzy combination fire clusters of neurons - we're not sure yet). These start two chain reaction processes - one along the dorsal pathway, and one along the ventral pathway. The former leads toward responses, the latter toward recall. All along the signals are suppressed by regions higher in the chain to minimise surprise signals. Eventually such chains will reach a response (fetching the red apple) and a recall (other things which are red apples from your memory), as well as emotions, desires etc. — Isaac

So why does it seem like we see colours?

The apple has a taste - two ontological commitments, that there is an apple, and that it has a taste. Why the third, that in addition to there being an apple and there being it's taste, there is also 'the way' it tastes? — Isaac

I would surmise that it is because the taste exists as an experience, and it does not exist unless it is experienced by someone. Therefore, it's the way it tastes for someone, or when someone experiences it. That is, the way it tastes is the taste experience.

The sensation of taste cannot have those properties to me because those are public words, those properties have public meanings. — Isaac

You mean that the sensation of taste cannot have those properties only to you. That doesn't mean that it cannot have those properties to you. But neither does it mean that it has those properties to everyone.

I can't possibly think one thing is 'sweet' whilst other people think a different thing is 'sweet' — Isaac

Then what of intuition pump #10? Perhaps perceptual norms affect linguistic norms?

I might be able to detect sweetness in something that other people cannot, but what sweetness is must be public. — Isaac

If it's not sweet/bitter for everybody, then maybe it's only public for some people but not for others?

We learn what 'sweet' means by experiencing the use of the word in our shared world, not our private one. — Isaac

Yes, but "if we construe the grammar of the expression of sensation on the model of ‘object and name’, then the object drops out of consideration as irrelevant." So our spectra could very well be inverted without either of us noticing.

You don't see a colour. Why Am I having to repeat this? You do not see a colour. There's no part of your brain which represents a particular colour. It doesn't happen, not there, absent, not present, unrepresented, lacking, missing , devoid. — Isaac

Then how do we distinguish colours? How is it that I am able to fetch a red object upon request?

I can't directly show you my perceptions or sensations, and neither can anyone else.
— Luke

That's a Cartesian view of perception and experience. — Andrew M

Why must it be?

So when you and I observe this red apple we are perceiving the same red apple. That's our contact with the world, and I'm showing you what I'm perceiving. — Andrew M

I don't disagree, but that's not showing me your perceptions or sensations. Maybe you're colour-blind and you perceive it differently to me. You can show me the object you are looking at, but that's not showing me how it looks to you.

If you're dichromatic, the red apple will appear dim yellow to you. But even in that case, your perception of the apple is not private or ineffable since I just described it. — Andrew M

Your description might tell me how it appears, but your description doesn't show me how it appears, which would make all the difference if our spectra were inverted.

Yes, a red apple could appear green to Alice and vice versa. But there would be a relevant physical difference between Alice and Alice's twin who sees things normally. This difference is potentially discoverable, and therefore potentially comparable. — Andrew M

I agree, it is potentially discoverable and comparable - I'm not trying to argue for anything supernatural. However, it remains private until then. Anyway, it's not really the privacy that's at issue here, but whether there is, in fact, some way that things seem to a person, i.e. some "inner" phenomenal experience. That's the definition of qualia given by Dennett, and what I understand eliminative materialists consider as somehow unreal.

once it is recognized that this is due to some physical difference (and not radical privacy or ineffability), then there is no longer a philosophical hard problem. Investigating physical differences is within the scope of scientific inquiry. — Andrew M

I have long considerd the hard problem to be a question of why, rather than how. Namely: why do we have phenomenal experiences at all? That question would not seem to be answered by a complete "map" of how all phenomenal experience corresponds to the body/brain.

How does our public language attest to the fact that you see the same colour as I do when we both refer to "red"? How can our public language help to show me your sensations?
— Luke

There's no guarantee it will. However when differences in people's observations are detected (such as a failure to discriminate colors), language can be used to describe it. For example, the dichromatic's experience can be described, and so is not radically private or ineffable. — Andrew M

A problem with this might be that a perceptual difference needs to be noticeable in order to...get noticed, and therefore some perceptual differences could remain undiscovered and private.

Do you suppose that the taste of an apple is somehow only available to you? — Banno

I don’t know; how does an apple taste to you (or to anyone else)? Can you show me how it tastes to you? What reason is there to assume that how it tastes to you is identical to how it tastes to me?

experiences are always already qualitative, so we have no need, in fact it will just produce reificatory confusion, to speak of the quality of an experience — Janus

If experiences are qualitative, then what’s the problem in speaking of their qualities?

You know, it's like the taste of beer; there's no experience of the taste of beer since the taste of beer is the experience, and to say that there is an experience of the taste of beer is like saying there is an experience of the experience. — Janus

I don’t see why it’s necessary to phrase it like that.

All of which we can talk about — Banno

Here you go again conflating qualia with language use. It is not the language use which is private, but the sensations.