This bit leaves me a bit confused though. When you say that "we're not detecting (2)'s; we're detecting numbers of events" are you referring to us or the photoreceptors under consideration? — creativesoul

Sort of (changed from yes); I'm referring to the number of photopsin molecules (available for detection). (2) has a particular effect on our eyes. A different (2) could also have the same effect on our eyes. So call the former (2a), and the latter (2b). The effect is (3x); (2a) would have effect (3x), and (2b) would also have effect (3x). Since we can't distinguish (2a) from (2b), it doesn't make sense to say that we detect (2a). What we detect instead is (3x). 3x is "an equivalence class of spectra". 2a is just a member of that equivalence class. 2b is another member.

I would argue that it is the same with colors. ... Color vision is far from only in the eyes. — Douglas Alan

I should point out for clarity that Douglas's description of color here is different than the one I've been presenting to you. They are, however, both correct... they're just focused on different things. The color concept that I'm describing could be called "colorimetric color"; that is indeed only in the eyes. Colorimetric color is about what we can possibly discern; it's the principle subject of colorimetry. What Douglas is describing we could call "perceptual color", which we can say is in the brain (though really that starts in the eyes). Since I'm just trying to explain the fundamentals to you, I'm focusing entirely on colorimetric color. I defer to Douglas for the rest, since that's what he volunteered.

I've been a bit busy; but I'm just going to fast forward to this.

So, it seems that we're not so much in disagreement aside from the claim you made that no other animal sees the frequencies that we call "red" as red. — creativesoul

You're still confused over the same point. There are three completely distinct things here: (1) frequency, (2) spectral distribution, (3) color.

Photons hit spots on our retina; but they aren't confined to having single frequencies (1's); they have distinct frequencies. But there's some distribution of them depending on what you're looking at... more at some frequencies than others. Because each photoreceptor is sensitive to a range of frequencies, then it's the entire distribution (2) that matters, not individual frequencies. But a given photoreceptor is simply more sensitive to some frequencies than others... at the photopsin level, it either folds or doesn't, but just has a probability of folding per photon based on the photon's frequency. That means you can make it fold with a given probability in multiple ways; you can fire less photons at the more sensitive frequencies, or more at the less sensitive ones. Since what matters for detection is simply the raw number of photopsin events, and there's multiple ways of reaching that number, then we're not detecting (2)'s; we're detecting "numbers of events". This is like a math function; in goes the photons, out comes some result... but it's the output (3) of that function that matters... you cannot distinguish what you cannot discern. The function isn't one to one, so it loses information.

Your "frequency=color" theory is fundamentally flawed; that's a misconception. If you really care about truth, get rid of the false things you believe. Consider for example Mary, who has only one photoreceptor type; namely, L. As it happens, L cones are actually sensitive throughout our visual band; so she's going to "see" the same frequencies (1) as us, and she's going to "see" the same spectral distributions (2) as us. But she won't see color; the whole "point" of having multiple photoreceptor types is to see color... to make the distinctions I described in the last paragraph. Mary has one photoreceptor type. So, if Mary looks at a 700nm LED in a dark room, she will see it. If you look at a 700nm LED in a dark room, you will see it. But you see its color; Mary does not. But Mary does see a 700nm LED. Therefore, color isn't "seeing a frequency we call 'red'"; it's something else. Think that through carefully... as a hint, though, I've already told you what color actually is. It's an equivalence class of spectral distributions; it's the output of that function I described in the last paragraph.

This is really where you're choking, so spend time on it. Once you grasp it, you'll realize that every photoreceptor-type combination leads to a unique color gamut. Once you reach that phase, you should realize that whether or not other animals see what we call red is a function of whether or not they see the same equivalence class of spectra, which means they have photoreceptors with the same sensitivities we do, and that is the thing that, whereas possible, is unlikely.

This is still the problem. — creativesoul

Thought you weren't interested?

Let's go back to this box of crayons. There are 96 crayons here; each is a distinct spectral distribution, and we see them as different colors. But that's kind of cheating, because these crayons were made for humans. Imagine our mantis shrimp has a box of crayons. There's 960 crayons in his box. When we open it up, we see one row in one compartment has crayons that all look like the same color yellow to us. Suppose one of these reflects only 700nm and 545nm light; call that crayon A; another reflects 570nm light only; call that crayon B. On the next row, however, we see orange crayons. Call one of these C.

So here's the key. Since each crayon reflects a single spectral distribution, then the two terms are pretty much analogous. So crayon=spectral distribution; crayons=spectra.

So, to the mantis shrimp, A, B, and C are different colors. To us, A and B are the same color; C is a different color. To Spot, who is a dichromat dog, A, B, and C are all the same color.

"Are you saying that no other animal perceives any of the sets of spectra we call 'red'"? Here, "are you saying that no other animal perceives any of the sets of crayons we call 'yellow'"? So let's get specific. We call crayon A and B yellow. There are two other animals; Spot, and the mantis shrimp. The mantis shrimp sees the set of crayons A and B. So does Spot. And why should this be surprising? The mantis shrimp and Spot both see; what has what they see to do with what we call things?

"No. I'm saying that no other animal perceives the set spectra that we call "red" as the same color."

Translation... no other animal perceives the crayons that we call 'yellow' as the same color. Again, we call crayons A and B yellow; and we call crayon C orange. Both the mantis shrimp and Spot see crayons A, B, and C (they see all of these spectra). But the mantis shrimp sees A and B as different colors. Spot sees A, B, and C as the same color.

This is still the problem. — creativesoul

Sounds good to me; yes, this is still the problem. If you don't get it now, I can do a "mathemagic" analog if you like next using numbers and equivalence classes as metaphors. But I can only explain this in so many ways; either you'll get it or you won't.

"Spectra"(capitalized for grammatical reasons only) IS a name. — creativesoul

Yes. Switching form, I'll quote you with quotation marks.

"It is used to pick out..." Yes."You said so yourself." I did. "Those distributions of intensities of light existed" Tense problem: "exist" is better. Other than that, spot on! "Those distributions are discovered." ...well, technically, yes. Because we have spectroscopes, prisms, rainbows, and brains, we discover the distributions. But as colors, we're seeing "equivalence classes of spectra". "Distributions of light do not require" ...yes.

"Colors are distinct from spectra." Yes; color is an equivalence class of spectra; spectra are the members. "Spectra map to the same color." Not necessarily; spectra that map to the same color map to the same color. "Metamers are the name given to distinct spectra..." yes. "That's not about our language use." Correct. "It's about color vision capability," ...correct; for example, for humans, it's about the human color vision capability. "It exists in it's entirety regardless ..." I'm interpreting this to mean that we don't have to know about spectra to see color; in that case, yes. "It most certainly" ...to me it sounds like you said the same thing twice, rephrasing it. "It requires colors" Yes, but, "colors require colors" is a tautology. "and spectra that map to them because it requires metamers" ...that works, but those aren't different things. "It does not require any of the language" correct.

"Color vision capabilities include" ...whole paragraph correct; but, it sounds like a repetition.

""Spectra" is a name." ...sure.

"It seems you're having a bit of trouble following along." ...no, you are having the trouble. "I've not talked about seeing a thing we've named red, as though that is the same as seing it's color as red." Well... you definitely said this:

Seeing red is the exact same thing as seeing the spectra we've named "red".

"You have. The earlier bits about seeing the crayons with the name on them and all that..."
...why does this confuse you so much? If I look at a box of crayons, I see colors. If a deuteranope looks at the same box, he also sees colors. But when I look at the crayon labeled red, I see red; when the deuteranope looks at it, he does not see red.

Neither I, nor the deuteranope, see spectral distributions; we're both incapable of doing so. I just see a crayon's membership in an equivalence class of spectra; that's red. Analogously, the deuteranope does not see "red"; he is incapable. He just sees a crayon's membership in a different equivalence class.
"Seeing red things is seeing things" ...yes.

Surely you are not asserting this. What are you doing with the word "so" here? So because "red" is a human word, it refers to a human group?

Again, what's confusing you? Humans created English. "Red" is a human word. So, human word? Check. Humans have human eyes; human color vision. Human color vision has particular properties. We made that word to talk about some equivalence class humans can see.

"Sorry, but I have to ..." ...okay, but it looks like the problem is that you're confused.

Using the term "red" in normal parlance is to pick out all things we've given the namesake to...

Huh? Which is it? Is it normal parlance or all things we've given the namesake to?

Spectra are not a human grouping. Color vision capability is not a human group. "Spectra" is a human word. "Color" is a human word. "Mt. Everest" is a human word. None of the referents of those words - which act as names - are human groupings. Human groupings are existentially dependent upon human language use. Spectra, colors, and Mt. Everest are most certainly... not.

Ah, you're choking on human grouping. Well, yes, humans invent language; and they make up stuff. That's not a bad thing; it's part of the human project. But, humans not only invent language and make up stuff; they are also animals of a particular type. We're primates, and we're mammals. We also have human eyes; human eyes tend to be equipped with trichromatic vision of a particular type. The particular kind of trichromatic vision humans have begins with the three cone types humans as a species have; the human species' L, M, and S cones. Those cones respond to spectra in particular ways; they are incapable of measuring spectra per se... rather, they measure equivalence classes of spectra. So there are equivalence classes of spectra that humans can see based on human physical properties. The equivalence classes are groupings. The properties are human. Therefore, these are human groupings, which means that, no, "human groupings" are not necessarily existentially dependent on human language use. This human grouping is "existentially" dependent on human cone sensitivities.

"All human groups are existentially dependent upon humans. Colors are not."

But human colors are; they are "existentially" dependent on human... cone sensitivities.

""Red" is a human word referring to that which existed in it's entirety prior to our naming and descriptive practices involving the term."

Red refers to equivalence classes of spectra that human cones resolve.

You said spectra are not colors, and also that green is a color... — creativesoul

"Even" is an equivalence class of integers. "Odd" is an equivalence class of integers. But "odd" is not an integer.

Only to people who do not understand that spectra exist in their entirety prior to our naming and describing them. — creativesoul

We're not naming spectra; we're naming equivalence classes of spectra. We're "color blind" to spectra; we can't even tell RG light from Y light.

Maybe that's your confusion. Dichromats, like red/green colorblind people, are "colorblind" because there are "colors" they cannot distinguish. We are trichromats, but physically speaking, that's just slightly more capable than dichromats. If we wanted to see spectra to approximately the same resolution as say the CIE 1931 spectral data... which has values from the wavelengths 360nm to 830nm in 5nm intervals... then we would need a hypothetical creature with 95 different photoreceptors.

Mantis shrimp have the most impressive visual gamut I'm aware of; with up to about 16 photoreceptor types.

Seeing red is the exact same thing as seeing the spectra we've named "red". — creativesoul

That's like saying that if I take a black and white photo of this box of crayons, then it's a color photo, because "taking a color photo is the exact same thing as taking a photo of things we call colored".

Seeing red requires seeing the color red, because red is a color. Seeing a thing we've named red only requires seeing a thing that we have named red, not seeing its color.

Distinguishing between the two spectra is not necessary for seeing both. — creativesoul

What do you mean "the two spectra"? There are many spectra that are red, and many spectra that are green.

Seeing them as the colors we've named "red" and "green" requires (a) seeing them as distinct to each other, (b) having similar biological structures as us, and (c) having already used the terms "red" and "green" to pick them out to the exclusion of all else. — creativesoul

Yes to (a). Not really to (b); that helps, but it's unnecessary. No to (c); it doesn't matter if you call the color "red", "rojo", "vermelho", or "aka"; what matters is that whatever label you're applying to it, it is the particular equivalence class of spectra that we have labeled red.

But you're missing a key requirement: (d) the ability to identify things that are the same color as the same color. In other words, if that crayon with "yellow" written on it is the same color as that banana on the shelf, then to "see yellow", you need to be able to see that that crayon is the same color as that banana.

Seeing them as distinct is not equal to seeing them as colors. — creativesoul

Correct; (d) is also a key requirement.

I'm pointing out the equivocation problems with seeing/perceiving and seeing/perceiving "as a color" — creativesoul

Actually, that's what I'm doing. You're confusing seeing a color with seeing a thing that has a color. Just because I call something red, and Joe sees it, doesn't mean Joe is seeing the color red. It just means Joe is seeing something and I see that it's red. We can't say that Joe sees the color until he sees the color, not just the thing that has the color.

That is not what I want to say, nor do I want or need to rethink what I've said — creativesoul

...okay, then you need to learn what these words mean, so that when when you read what I write you're interpreting it correctly, and so that when you write something using those words it means what you say... so that when you write something, I know what you mean.

Seeing a spectra "as a color" is to have already named that spectra, and to have already categorized that name as a color. — creativesoul

"Spectra" is plural, first off. We're talking about particular spectral distributions; since we're using "spectra" as a shorthand for the plural, you can call each of these a "spectrum". So take this box of 96 crayons here. There is a red crayon; it reflects a spectral distribution, which means that there's light from wavelengths (say) 360nm to 830nm being reflected with particular intensities at particular wavelengths.

One can see a class of spectra without ever having given it a name.

But that phrase doesn't mean anything useful. The term class refers to just a grouping; taking spectral distributions and putting it into a box (label not needed; just boxing). This isn't just a nit pick; we need to be able to talk about classes like this if we want to talk about whether other entities see the same colors we do, because the thing we are talking about has to allow us to transport one "class" to what another entity sees.

There is a spectral distribution that the crayon with "red" written on it reflects. There's another that the crayon with "green" written on it reflects; another that the crayon with "yellow" on it reflects; and still another that this banana on a shelf reflects. There's a class of spectra that has all four spectral distributions in it; one that has just the banana in it. Yellow is an equivalence class of spectra we can distinguish. We cannot distinguish the spectral distribution the banana reflects from the one that the crayon labeled "yellow" reflects; therefore, they are in the same equivalence class.

But when you talk about a different entity; say, some creature called a "snapper", seeing "a class of spectra", then it doesn't really mean anything useful. That means snappers can see things in the class, which means snappers can see crayons with "yellow" written on them, and they can also see bananas. Well, okay then; but in that sense, deuteranopes can see all 96 crayons... so when you tell me snappers can see the class, I'm not sure you're telling me anything about colors.

So, seeing a spectra and seeing a spectra as a color are not equivalent processes.

Of course they aren't. That's the point. Talking about "seeing spectra" underspecifies what it means to say they are seeing colors. The colors the snapper sees is defined not by what spectra it can see, but by what spectra the snapper can distinguish versus what it cannot distinguish. Non-distinguishability is same-coloredness; distinguishability is different-coloredness. The banana and the crayon are to us the same color because they are in the same equivalence class of spectra based on what colors we distinguish.

One cannot see red or green as colors however, unless one has used the names "red" and "green" as a means for distinguishing between the two spectra bearing the namesakes.

No, if it were about assigning words to the spectra, we can't talk about snappers seeing color, because snappers don't use words. And they don't use words to distinguish spectra either... they use their snapper eyes. Furthermore, they don't use their snapper eyes "to distinguish spectra", because that's not the "purpose" of what they're doing. They're just using their snapper eyes to see what things look like... snappers couldn't care less about spectra, they just care that things look the same or different. It's just that their snapper eyes in and of themselves distinguish or not spectra of particular types.

The words are just labels; "yellow" literally is just a thing we use to label the color. The color per se is an equivalence class... that we have labeled with the word "yellow". That equivalence class consists of spectra such as that that the crayon with "yellow" written on it reflects, and that that the banana on the shelf reflects.

But the an idea doesn't necessarily relate to any one thing, the an idea may be related to many things, — Metaphysician Undercover

FTFY.

Yes, "an" idea may refer to multiple things; for example, by referring to multiple tokens; or, by referring to a type with multiple members.

You formulate the signs within you mind, what you will type, before you type it, just like you formulate what you will speak before you speak it. Then the typing is just a representation of what you have already formulated in your mind. The act of formulating the signs occurs within your mind, not on the keyboard.

I'll grant that you're talking about something that happens, but you're still off on the definitions. Telling me that it happens is beside the point... it is not a sign until it is fixed in a medium. The things you do in your head leading up to the sign comprise intentional actions; that certainly requires goal setting and initiating actions directed towards attaining those goals. The thing you're "thinking of" that you want to type should indeed predate the typing of it. But you're not producing a sign until you actually wind up typing it.

Signs don't even have to be specific results of intentions per se. My DHCP server for example pops up signs like: "Assigning IP Address 192.168.1.201 to ...". I can read and interpret that, even though no person typed it (certainly, no single person as a whole, even if you trace history). Also, signs don't have to be in traditional language; stop lights are signs (in this sense even).

Other animals can perceive the class of spectra that we've named "red". "Red" is the name we've bestowed upon a certain class of spectra. The name of a thing is not the thing. "Red" is not red. Red is a certain class of spectra. Other animals can perceive that certain class of spectra. Other animals can perceive red. — creativesoul

There's a box of 96 crayons here. I can not only see every crayon in this box; I see every crayon in this box as a color. A deuteranope (red/green colorblind person) can also see every crayon in this box; not only that, he sees every crayon in this box as a color. By your argument, a red/green colorblind person should be seeing red and green. Is that what you want to say, or do you want to rethink that?

Yes. Right? — creativesoul

Yes, but, this is getting ridiculous. You're treating this like a chat forum. Why don't you just go think about things, and come back in a bit? Or suggest an actual chat forum to talk on?

Can other animals perceive the class of spectra that we call "red"? — creativesoul

You need not go to other animals; deuteranopes (that mode of red/green colorblind) can see the class of spectra that we call red. They can't distinguish that color from the color we call green, but they can see the same class of spectra.

The question of whether an animal can see the same class of spectra that we can is simply a question of whether the animal's visual bandwidth (by which I mean the range of light frequencies that is visible to it) is the same or broader than ours.

It's fascinating, although I expected a story about visual cortex area V1. — Zelebg

I'm not as well versed in the visual cortex, but I am aware that certain areas of the visual cortex analyze images at different resolutions, making this even messier.

I'm wondering if it makes any sense to drop off the "as the same color" portion. — creativesoul

Why would it? Aren't we supposed to be talking about what colors are? If RG and Y are both yellow, they're both yellow.

Can they perceive the class of spectra? — creativesoul

I have no clue what you're asking here. The class of spectra that I can see is the same class of spectra that a deuteranope can see. I suspect you're trying to ask some question but don't know how, but I honestly can't figure out what you're trying to ask.

It may become relevant. — creativesoul

You're explicitly being evasive; okay.

Are you saying that no other animal perceives any of the sets of spectra that we call "red"?

No. I'm saying that no other animal perceives the set spectra that we call "red" as the same color.

Critically speaking, you're committing a few fallacies, but I do not want to focus upon that. — creativesoul

Then why tell me?

Is this close to being in line with what you're saying?

Sorry, but no.

how you've arrived at the notion that no other animals can distinguish the spectra that we call "red" regardless of the vagueness and/or lack of precision that that term carries along with it. The term does have a corresponding range of frequencies that it picks out.

No, the term does not have a "range of frequencies" that it picks out; it has a "set of spectra" (an "equivalence class of spectra" if you will). Suppose your monitor's RGB components were monochromatic... and R emitted at 700nm, G at 545nm, and B at 435nm. Suppose also that you have a 570nm LED; when lit, that LED would emit light that you would see as yellow. You could also produce that same color (close enough) using your RGB monitor. But when you look at at your RGB monitor, you are not seeing 570nm light; you are seeing light composed of 700nm photons and 545nm photons. Photon frequencies never blend; a photon at a frequency is a photon at that frequency from the time it's emitted to the time it's absorbed, regardless of what other photons are present (for the same reason, you don't get an AM radio station at 570 kHz by putting up a tower at 545kHz and another at 700kHz).

So the combination of light coming from your monitor... that mix of 545nm photons and 700nm photons... is one spectral distribution (call this RG light). The light coming from the 570nm LED is another spectral distribution (call this Y light). From the physics of photons, there's nothing about RG light that "makes" it the same color as Y light. What makes RG light and Y light the same color is how your human eyes react to these two spectra. RG light and Y light are metamers for the color we call "yellow".

There was nothing before the Big Bang. There was no time, so only a motion exists. — Gregory

That's not necessarily true. The Big Bang is most precisely a singularity; that's it. This does not imply there was nothing before it. In eternal inflation models, for example, big bangs (as singularities) can spontaneously arise from the formation of false vacuums; and this happens indefinitely into the future. Under such models there's a sense in which one can talk about things before big bangs.

A separate reply for this:

The Law of Conservation of Matter and Energy states: matter and energy can neither be destroyed nor created, but they may interchange from one to the other. This being said, we must conclude that either there has always been matter, or that there has always been energy or that there has always been both. — OpinionsMatter

This is a misunderstanding. Conservation of Energy is a law because it's something we've noticed occur under certain limits and it has a mathematical form; not because the universe is compelled to obey it. In fact, strictly, we think the universe as a whole does not obey this law, because the universe isn't symmetric in the right way.

You might be interested in what Nick Lucid says about this:
https://www.youtube.com/watch?v=cnGYMe6GBeQ

Let's analyze this and try to find out what this thread is about.

There is a term "nothing". When we look at it that term, we have a particular idea about it. When we talk about it, we use that word. There is a claim here that the human brain cannot comprehend this.

So how would I falsify that claim? Assuming it were false, what criteria should I be meeting to convince you that it is false?

Let's take a side step. There is another term "pencil". When I look at that term, I have a particular idea about it. When I talk about pencils, I use the word. So do I comprehend pencils? I don't know; depends on what your criteria is for "comprehending pencils". What thing has to be, in order for you to say that I comprehend pencils?

Maybe that's good enough, or maybe not; if not, one argument might be that it's a false equivalence... since pencils are concrete, that makes this special. Well, okay then. Do I comprehend superman? Do I comprehend primality of numbers? Do I comprehend "adverbs"? Do I comprehend "economic recessions"?

One quick observation... I understand absolutely none of these things fully, so if the criteria here is to "understand fully", I cry foul. Two cases can stem from this... either you want to say I comprehend pencils, in which case this is special pleading saying that I don't comprehend "nothing"; or, you want to say I don't comprehend anything, in which case I say, fine... but what's so special about "nothing"?

Now I'm not giving an argument for why we do indeed comprehend "nothing" here... but rather, what I'm saying is that we had better know what the rules are to this game if we're going to play it, lest it just be pointless.

Which would mean that we have never had complete nothingness, there has always been something. If you believe in God, than there has always been God.

An observation... you're mixing the concept of "time" here. One could say that "there was at one time nothing" is simply a contradiction... because if there was a time at which there was nothing, then there was not nothing then... there was a time then.

If someone asked you to imagine 'nothing' and than I asked you what you saw, it would make sense for you to say 'nothing'. However, you may see a vast expanse of all black or white, or even maybe some glass like something.

...unless you were blind from birth and had no concept of a visual experience, or you were clever enough to imagine "nothing" by not imagining anything. This may really be nothing more than a language game; and the same sort of contradiction. It might be that you're asking us to imagine something that is nothing, and don't actually count imagining nothing as imagining nothing.

But you can't do that with 'nothing'.

How do you know? By that, I'm not asking you to give me your reasoned argument; I'm asking, how is it that you can even give a reasoned argument coming to that conclusion if you don't "comprehend nothing"? Also, it's not meant as a challenge, it's just a question. There's something about your ability to recognize that you're not comprehending nothing that requires at least explaining in terms of how you're able to come up with the notion that we cannot do it.

So I really want to know what the rules are.

But the act of "calculating" which a computer does, is nowhere near to being similar to the act of "calculating" that occurs in a living being's act of perception, so the redefining is pointless. — Metaphysician Undercover

You do realize that before "computer" was a type of machine, it was a job description, don't you? Calculation is just a more abstract term than you're making it out to be; both Dr. Nim and myself can calculate. Computation, equally so... both the thing your keyboard is connected to, and an employee, can compute. But, yes, mechanical computers calculate in a drastically different way than we do.

The idea relates directly to the sign, and the sign only.

...quick side note; it's quite a bit messier than this. Signs quite often, in practice, underspecify intensions (and often, only indirectly convey them); real language use tends to invoke a lot of context.

But you misrepresent this application with "a thing to which the idea refers". There is no such thing, only possible things. — Metaphysician Undercover

This critique is incoherent to me. Are you saying, there's no key under your pinky, only a possible key under your pinky?

See your confusion? The attempt to formulate a sign, is an application of the idea, an attempt to find "possible things" (signs) which fufill the criteria of the idea. Therefore it is an extension, not an intension as you say. — Metaphysician Undercover

Huh? What are you talking about? When I convey ideas to you in the forum, I formulate signs by typing. That generates signs on my screen, and eventually generates the same signs on your screen. The signs I type are an attempt to get you to form the same idea. I'm at a total loss what you're talking about when you say I am "finding" the signs, or that they are "fulfilling the criteria of the idea".

If you're trying to convince me that you're not confused, but I am, then you're off to a bad start.

This is false. Reasoning is carried out with the symbols (extensions),

That doesn't work:

Extension (semantics) the extension of a concept, idea, or sign consists of the things to which it applies ... So the extension of the word "dog" is the set of all (past, present and future) dogs in the world: the set includes Fido, Rover, Lassie, Rex, and so on — Wikipedia

...when describing world objects, the extensions are those world objects. When you reason about world objects, those world objects are not symbols, and you don't reason "with" them (I suppose you could; if we want to call that reason... if, say, I'm making use of a calculator, I'm reasoning "with" a calculator, but I suspect this isn't what you mean). You reason with your ideas about those world objects. (Now that can be comprehensions, but it's never going to be an extension, so long as you're talking about world objects).

Forming an idea is intensional, while applying the idea is extensional.

I've no problems with this.

All I am saying is that this "stuff going on in your mind" is better represented as a type of "reasoning" (though it may not be conscious reasoning), than it is represented as "sensing".

Well... except that makes the term "sensing" a not so tidy concept.

Perhaps we'd be best off to compromise, and conclude that it is neither sensing nor reasoning. — Metaphysician Undercover

How is that different than what's already on the table... just calling it some other thing, like, "perception"?

Spectra and colors...

What's the difference? — creativesoul

Spectra is shorthand for "spectral distributions", and refers to the distributions of intensities of light as a function of frequency across a band of frequencies. Color refers to a component of vision. Colors are distinct from spectra in that vision is not capable of measuring spectra in any animal's vision; for any animal capable of color vision, there will always be "metamers"... distinct spectra that map to the same color.

The computer proceeds according to the algorithms by which it is programed, it does not calculate. — Metaphysician Undercover

Dr. Nim performs calculations in this sense; it employs a deliberate process that transforms inputs into outputs. But it's not programmed; a program is a set of instructions for a computer to follow, but Dr. Nim has no instruction set.

I'm sorry, but no matter how hard I try, I cannot understand this statement. Can you explain? — Metaphysician Undercover

Consider "the letter A on your keyboard"; for now, that literal phrase. That is a sign. When you read this sign on the screen, you formulate an intension... the idea of what this phrase means. There is a thing to which that idea refers... and that thing is an extension; that is the actual key. What's nice about this example is that there are spatial metaphors that help you keep these things straight... the sign is on your screen. The intension is in your head. The extension is under your left pinky.

So let's go back to that confused thing you said earlier. The example was, I saw a rock rolling down the hill. That is indeed a judgment; which I'm explaining by the phrase (sign), "a rock rolling down the hill", which you read on your screen. The judgment is an intension; it is something I do in my head. But the intension is about an extension... which is the thing rolling down the hill.

Now let's rewind even earlier. You talked about sensing sound. Then I said, it's not really sound we're sensing in that sense of the word "sense"... and gave an analysis of the ear organs. Then your confused criticism was:

as soon as we try to say "what" we're sensing, we're not talking strictly about the sensation any more, but we're referring to some logical conclusion, some reasoning as to "what" the sensation is. — Metaphysician Undercover

...and that's the confusion. You're confusing what's under your left pinky with what's being done in the head; what's rolling down the hill with what's happening in the head. The phrase "try to say" means to attempt to formulate a sign; a thing on your screen. "'what' we're sensing" refers to an intension. The conclusion you're reaching, that this implies we're "not talking strictly about sensation any more, but we're referring to some logical conclusion" conflates intension with extension. Intensions are about extensions; that's how this works. Using reasoning is something you do with intensions. The only way that talking about something makes the extension a logical conclusion is if the thing you are talking about is the making of logical conclusions. Merely using logic to reach a conclusion doesn't magically change what you're talking about into the making of logical conclusions, but that's precisely what I'm reading that you said here.

Right, this was exactly my point. Maybe we actually agree.

Possibly; my best assessment of your criticisms against me is that you're just failing to grasp what I'm saying... up to now it feels more like a definitions fight. But I think my point is really important for someone trying to take a subjective point of view, because from that point of view, there's a huge difference between the things you can access introspectively, and the things you cannot. And there's a lot of stuff going on in your mind before we even get to that arena where your introspective view actually tells you something. The stuff that happens with your signals on your optic nerves that leads up to your percept (aka, "perception")... that's outside of the introspective field. The kinds of things you can reflect on and talk about (aka, natural reasoning)... that's inside.

The term "red/green colorblind" I think is nonsense to apply to a dog. Red/green colorblind is a term that can apply to protanopes (humans with L cone "deficiencies") and deuteranopes (humans with S cone "deficiencies"). Dogs, protanopes, and deuteranopes are all dichromats, but protanopes and deuteranopes have two of the three human cone types; whereas dog vision is distinct from both protanopes and deuteranopes. Dogs aren't "red/green colorblind"; they're just dichromats. Be careful not to over-objectify human trichromaticy.

What makes you so confident that no other animals can see red? — creativesoul

...because the odds are incredibly against it. Red is a human color category; it requires human trichromaticity to define. To get that, you essentially need human alleles in your gene pool, which I doubt other animals have.

Trichromatic animals by all odds, as I explained, are likely to have different color gamuts that don't match up with human color categories. Maybe they distinguish certain spectra better than we do; maybe we distinguish certain other spectra better. There may be matching colors to them that we can distinguish, and vice versa. "Red" is a human word, so it refers to a human group.

Some can sense infrared, others ultraviolet. — creativesoul

That only makes things worse! Suppose protanopes were the norm, and suddenly humans started evolving trichromacy. Maybe, 5% of humans can see three colors. But all the words we have for colors are things like "gold", "blue", and such. For us 5%, there are drastically different kinds of "gold"... "red", "orange", "yellow green", and so on. But there's no word for it.

Now let's assume the impossible happens... there's an animal with three photoreceptors who have the exact same sensitivities as our human L, M, and S cones, but it has a fourth. So now, you're going to say that it can see red? Which red? To this animal, there may be drastically different kinds of red, all different colors. We don't have names for those colors; we just have deficient names like "red". Assuming we can name the colors they see, we have to invent all new names for these colors.

It's even worse if they are tetrachromats and they (as is more likely) do not have matching photoreceptors. Not only do we invent all new names for their colors, but their names don't really align well with our names.

Nope; I objected to that notion because I think the existence metric is silly. If there are real humans, with real properties, that see a particular color gamut; then those colors are real, and defined by those real humans. The alleged metric that "if there were no humans there would be no such colors, therefore colors aren't real" to me (as I phrased it) sounds as ridiculous as saying that rabbits don't exist because, if there were no rabbits, there would be no rabbits.

It's a little more complex than this. Say you have six balls... three green, and three red. You go to your friend, who just so happens to be a protanope; he's red-green colorblind. But that doesn't mean he can't separate your balls into these groups; he still might... he just won't have red categories. He's just not guaranteed to; it would be difficult if these balls were all the same brightness as each other, for example, or these were all wildly different variants of red and green and the "redness" is the most distinguishing characteristic.

That's just straight up dichromacy versus trichromacy in humans. I would guess a trichromatic animal might have a better chance than your protanope friend at matching these balls, but again, it's still not guaranteed, because such an animal would be seeing different colors.

Well it's all the same spectra... so it's a matter of whether or not the animal can distinguish the things we identify as red and recognize them, which would be possible if they see different colors, though not guaranteed (and not necessarily guaranteed for all objects).

That's not true.

Of course it is. "Red" is a trichromatic color category; it's roughly an equivalence class of spectral distributions defined by the differential stimulation of erythrolabe and chlorolabe, which are uniquely human proteins. Humans have a distinct gene pool with alleles for creating these proteins; any other animal, even if it were trichromatic, is highly likely to produce different proteins. Different trichromatic photopsins imply different groupings of spectra into metamer groups, which means different colors.

ETA: The way these photopsins work, there's a general overall shape and a coding for it on the genome. Slight changes in the production of these photopsins change the shape and makeup; which changes its photosensitivity spectra.

Humans are not the only creatures capable of seeing color.

But humans are the only ones that see "red", "green", "yellow", "blue", "brown", and other colors humans talk about. Humans are the only ones matching paint colors; selecting paints for art, building traffic lights, and so on. Restriction to human colors isn't a flaw of lexicons; it's a choice of lexicons.

CIE 1931, for example, makes no pretense that it's about how cows see color.

How can you say that these calculations are "pre-rational".

Pre-rational here means these calculations occur before rational thought.

This would mean that there is a way of calculating which is not rational.

Dr. Nim (the board game/canonically famous, genius, and simple mechanical computer) performs calculations, but does not employ rational thought.

Rational thoughts are about things; that's what Dr. Nim isn't doing. Dr. Nim has no idea what those marbles are about, or even that it is processing marbles. But Dr. Nim is performing calculations.

Plainly and simply, without that judgement, there is no such scenario.

This is a confused and ambiguous statement. We have an intension (judgment) A; with an extant extension (scenario) B. If you're saying that A's extension (B) would not exist without the formation of the intension A, then it's an absurdity. If you're saying that we cannot have an A referring to an extension B without the formation of the intension A, then it's a vacuous irrelevancy.

This same intension/extension confusion is really the missed point of the thing you replied to... just because I use natural reason to describe a thing does not mean that the thing I described is employing natural reason.

But if you agree that recognition requires such a comparison, how do you think this act of comparison is not an act of "natural reason"?

Why do you think it entails natural reasoning? All a comparison requires is a calculation. We can compare variable states on a computer using a comparison operator... computers are (at least generally) incapable of natural language; they calculate, but do not reason.

ETA: Let me backtrack, because you keep trying to push some point you're making (but only by conflating things) and keep missing the same one. Let's go back here:

Suppose a creature sees something as an object of food

...so here I say, back up. Why are we talking about this creature seeing things like "objects of food", when mechanically speaking, such a creature would be seeing "a bunch of stimulated cones on a retina"? Once you're talking about objects of food it is impossible for you to have not gone through calculations requisite to identify what parts of those stimulated cones correlate to edges of objects, what parts are part of the same object and what parts are part of different objects, what shapes the objects are, what colors (if applicable), and so on.

There's some reason why you're starting at objects, and not stimulated cones. What is that reason?

I think that if you believe that you can talk about what you're sensing, without using some sort of reasoning to make conclusions about what you're sensing, then you are absolutely mistaken.

I think you're severely confused about the very subject of the conversation.

What I'm telling you is something like this. There are signals coming to my brain across my optic nerves; roughly 1 million channels. When I look outside, I'm not sitting there with a spreadsheet, analyzing each of those million channels using natural reasoning, and reaching a conclusion that there's a bird there. What's happening, instead, is exactly what I told you is happening... there's a huge juicy chunk of calculations being performed pre-rationally on those million channels of data.

Now I'm definitely saying words, like, "there's a huge juicy chunk of calculations being performed"; and that is most certainly an analysis... it's not only reasoning, it's employing extant science. But that changes nothing here; I am definitely not analyzing each of those optic nerve signals rationally.

How can you say this? Clearly you are referring to conclusions. You are making conclusions that the objects are on the movie screen and not actually there.

And? Just because I describe something using reasoning doesn't mean the thing I describe uses reasoning. If I see a rock rolling down a hill towards a car, I might reason that it would hit it; but that doesn't mean the rock is employing reasoning to hit the car.

When I look at a peripheral drift illusion, I see motion. The thing that leads me to see motion is a pre-rational judgment; and that thing is multiple levels above the cones being stimulated by photons reflected from the image. Digital cameras alone don't in any meaningful sense sense "objects" or "motion"; neither does the eye. To get from those "eye pixel" analogs to this pre-rational judgment that something's moving requires tons of analysis, but that analysis is nevertheless pre-rational, not a result of "natural reasoning".

"Perception" requires some form of recognition, and "recognition" requires some form of natural reason. Suppose a creature sees something as an object of food, that is a case of perception. But to see it as such, something to eat, requires recognition and therefore some form of natural reason.

I recognize this argument as valid. But I reject the premise: "'recognition' requires some form of natural reason." So I don't recognize that it's a sound argument.

The calculations that take the stimulation of individual cones when I look at that peripheral drift illusion to a recognition of motion definitely do occur; but they are pre-rational. The same thing happens when I see "objects"; there's a pre-rational judgement. The distinction is quite dramatic... it is why for example, despite knowing that nothing is moving in a peripheral drift illusion, I nevertheless still see it as moving. It's also why I cannot explain to you why I see it as moving (by introspection anyway). There's a distinction between such pre-rational judgments that inform percepts, and the employment of reasoning to reach conclusions. Furthermore, when we reason about the world, we don't start with details like individual signals on optic nerve fibers... we start far later in the game, like, seeing an object here moving there.

information like what is the size of perceived pixels or their molecular representations and how many of them are there. In other words, what is the resolution of the human inner display?

Well... it's a little more complex than this... a digital camera is "pretty", so we can talk about such things in very few terms and have a good idea of its structure... but the eye is quite messy.

The easiest answer for resolution appeals to the astronomy type metrics; we can resolve details at about under 1 arc second. But cones aren't equidistant; they're more packed in the center, and vary as you move out. Our fovea covers about 5.5 degrees of visual field; the foveola (the sharpest part of our vision) about 1.5 degrees. There are about 5 million cones in the eye; and about 90 million rods (keep in mind, we do have a "scotopic vision" (night vision) mode as well). But of the 5 million cones that we have, a large number of them just feed inputs into ganglia that combine signals from multiple cones; many of these are responsible for the "opponent color" process; for example, there's a "red/green" channel that "calculates" the difference between L and M cone stimuli (loosely, L-M). There are also ganglia combining inputs from the same cone types, again, in our retina... these play a very early role in edge detection. The foveola is a strange exception; "optimized" for resolution, it has no blood vessels, and no rods; only L and M cones (no S even)... and the ganglia in this region map one to one to each cone. So a lot of those 5 million cones in our retina aren't directly giving signals to the brain; in fact, the optic nerve is somewhere between 0.7 and 1.7 million fibers thick, if that give you an idea.

Believe it or not, this is the short version!

Colors are far more complex than simple wavelengths of light. Most colors do not correspond to any wavelength.

^-- this!

Physicists often use the word "color" and associate it with frequency of light. Some of these poor saps are confused; among those not confused, this can be read as technical jargon, but just as some physicists have tended to move away from using two terms "mass" and "rest mass", they should stop calling such a thing "color" and use the other perfectly good word for it; "frequency", because it has nothing to do with that thing that we humans give color labels to.

The thing we humans give color labels to are categories whose core physical basis is not the frequency of light per se; but rather, is the definitive biophysical process that can form said categories. And that basis is the photoisomerization of erythrolabe, chlorolabe, and cyanolabe. In lay terms, there are three kinds of proteins, one per cone cell, that can absorb photons and fold (and we're talking just cones, because color vision is a particular mode, dubbed "photopic vision", where there's sufficient light to drive it; in photopic vision, rods are basically just saturated, and therefore useless). The manner of such folding happens with a probability that depends on the protein kind (the photopsin) and the frequency of the light, but the thing we sense is this folding, not the frequency. If an erythrolabe molecule folds (isomerizes), it begins the chain reaction that (may) eventually lead to signals, no matter which frequency of light it absorbed to fold. There are many cases of spectra that have equivalent probabilities of folding these photopsins; because of this, a lot of colors are "metamers", which is to say that have distinct physical representations for the same "base" color category. Beyond this level of color categorization, our brains cannot tell the difference, so this is the right level to think of the physics of color. Saying that color is "supposed to be" about frequency is a bit baseless; color just is what it is.

There is a science of measuring colors; it's called colorimetry... one of the go-to popular standards of color measurement is the CIE 1931 model. This is simply a two dimensional measure of a color space; there is the third dimension, but this is the type of thing we're really talking about when we mention color.

Lay philosophers love to talk about qualia, but I think that's the wrong point of analysis. Just jumping in the water, let's ignore all controversies and presume fully that we experience qualia as typically described. Here's the problem... qualia are ineffable, but colors are effable. Your red-quale is just a thing you yourself have; you have no way of comparing it to Joe's red-quale. Your red-quale is useful in terms of color because it's available to you, and because it's presumably the same quale for the same color... so you can measure the thing we agree is red, but it's the thing we agree is red that is the color, not the quale (in any meaningful sense, by which I mean "meaningful" in a semantic sense... namely, the ability to assign extensionality to terms).

OTOH, colorimetric color is only the beginning; our perceptual apparatus adjusts colors automatically; several optical illusions prove this dramatically. If we want to talk about "the color of an object", that is a brain computed thing. But I think it's meaningless to say that things specific to working humans aren't real, but things non-specific to working humans are, because, call me crazy, it's my humble and honest opinion, and I have no idea how someone would argue against such a thing, that working humans exist. Running down this line as an existence metric, as far as convincing me something meaningful has been said, one may as well tell me that rabbits don't exist, with the reasoning that if there weren't any rabbits around, there would be no rabbits.

So the way the ball bounces for me is quite simply as follows. Ten humans can independently measure something called "the color of this banana", and agree far more often than random chance. OTOH, the actual spectra that banana reflects changes dramatically based on where it is and time of day; and really, it's not the spectra per se that even matters, it's the colorimetric categories... but even these are quite distinct. So I've no problems with someone saying color isn't measuring spectra; and whether you focus on colorimetric colors or "the color of bananas" to me is simply a matter of definitions, but these are distinct things. But nominal human vision is part of extant brains that are performing physical measurements, so despite this stuff being specific to humans, humans do exist, so... why not just say colors do?

I'm voting no; it doesn't matter. For "the definition" of free will, I take the linguistic approach; which is to say, I don't define free will. Instead, I try to analyze how the term is actually used by native speakers of languages.

That's where things start to fall apart here... people use the term differently. That per se isn't that bad; terms can have different definitions, but something's a bit off when it comes to this particular term. There are lots of "sub-theories" that slip into the free will range; misconceptions about determinism (confusing it with fatalism) for example. Compatibilist notions of free will are cleaner in this regard, but linguistically a fair amount of people disagree that such notions are what is meant by the term.

To illustrate, picking on Relativist, he says free will matters, because it's the basis for a concept of responsibility; but he seems to lean towards compatibilism. Sam Harris argues, however, that free will is kind of a cruel religious hold back, and it matters that we get rid of the concept. He argues as far as I understand that determinism is true, and therefore we don't have free will. But, he also thinks that responsibility matters, but just doesn't require this hold back.

But even under such analysis, "free will" is really a derived concept in a theory of mind. And that's where the second problem comes in. We're all agents; and we are imbued with a conscious mind. We can also introspect; and I'm all for introspection; I love exploring the subjective. The problem, however, is that introspection can only show you what introspection can show you. As social creatures, we fill in the gaps with socially collaborative theories, which works well for being functional and members of the human project, but I'm not quite sure we have a really good theory of minds. I think we should be a bit cautious and skeptic here, however; precisely because we're so familiar with our own agency, but only see the tip of the iceberg. The issue here is that familiarity can "feel" like expertise, and we can easily fall into the trap of thinking we know what we're talking about when in fact we're speaking complete nonsense.

There are hints that something strange is going on. People can form opinions of and characterize other people in terms of core traits, for example, but such projected "properties" of the same person differ depending on who is measuring it. And control per se... as in that thing you do when you move voluntarily that you're not doing when moving involuntarily... is a real phenomena, but doesn't really fit precisely with the general notion of free will. Regarding the same, though, it turns out that control can happen both consciously and non-consciously; which suggests maybe choices can. I don't think the "conscious deliberation theory" of action holds any water... when introspecting it's obviously proven false fairly quickly; in practice, when we act, even morally, we don't pause and contemplate what we want to do every time consciously... in fact, we do that very rarely... quite often, there's just no time to do it. But I don't think equating "us" to our "conscious minds" is accurate either, for the same reason. Also, there's kind of a sliding door as to what we're trying to talk about when we speak of free will; a tick is definitely involuntary... breathing, can be controlled, sort of; sneezing controlled very slightly, occasionally. We seem to be capable of wanting and not wanting and not wanting to want the same thing simultaneously; there are habits, addictions, and compulsions... somewhere in this mix there's a theory of mind that explains why we do what we do when we do it, and it seems like a large portion of this is beyond that introspective firewall.

I think if we want to figure this stuff out for real, and not just endlessly debate it, we should just ignore this linguistic level on top of our current lay theories and just investigate the raw why we do what we do when we do it, at levels deeper than what we have subjective access to. Then we might find room to define the free will problem properly; but it's possible we would simply outdate it with better theories instead. In the mean time, the actual free will problem doesn't seem all that useful IMO, because we're unqualified to say what exactly that problem is.

What you are sensing is some sounds.

Not exactly. What I'm sensing is cochlea hairs bending. An organ is mapping sounds (say, vibrations of my eardrum) to physical locations in the cochlea (via the hammer/anvil/stirrup/cochlea shape+fluid systems). That may sound like a nit pick, but I think it's perfectly fine to distinguish sensation at this level if you choose... but if you do so, you can't really say we're sensing sound, because we just plain aren't. We're sensing specific frequencies formed by sound (as produced by this sensory organ, which in my mind amounts to a bio-physical computer calculating the frequency components of sounds)... that's it.

The only way to conclude that the sounds are coming from a bird is to employ some form of logic. Not all logic is formal logic. If it helps, instead of "logic" we could call it some form of reasoning.

I think you're confused on a few levels. I referred to natural language; formal logic uses formal language. So this isn't about formal logic versus informal.

But if it helps, sure, let's agree it's a form of reasoning. But now, there's still two qualitatively different, massively distinct forms of reasoning. One form I call "perception"; the other, let's call "natural reasoning"; natural reasoning is of the type that you can "reason through", that is, that you can think through using a natural language, hence the name I just made up for it. That includes not just "here is the proof for this math theorem", but also, "here is why Jack Johnson is a better candidate than John Jackson". Perception is not "natural reasoning"; it's entirely distinct. One might could actually write down the logical progression of perception, but not in the same manner as we do natural reasoning... where we just self reflect and just spew out some diatribe. Nay, filling out how the perception works requires an analysis akin to figuring out how other external phenomena works, even if its our own perception we're talking about. We're not "privy to it"; we cannot "backtrack the reasons" behind it. In other words, we cannot (in this sense) "naturally reason" about it.

if we do not separate these two, we cannot account for the fact that we make mistakes in determining "what" we are sensing.

That leads to the second point... perception "nominally" may lead to conclusions, but doesn't have to, and quite often does not. When I watch a movie I "see" objects moving on my screen, but I don't believe they are actually there, nor do I believe they are moving. And if I watch a magic show, I may perceive all kinds of oddities going on, but not conclude they actually are; likewise if I flip through books of optical illusions. What we're talking about isn't what's being concluded, it's what is behind a percept.

I think that's the level that you're missing... you go straight from "sensation" to "conclusion" via "reasoning"; in a sense, so do I. But when you do so going from "photons" to "there's a bird there", you're missing a huge chunk... you're missing all of that juicy "perception" stuff. I've got the line where "mistakes" can happen, sure; that's how we can even define objects we call "optical illusions"... they are the ones where the perception suggests a reality that our natural reason concludes isn't there. But the ability to define and talk about such objects I think is what you're missing, so that's my advantage.

That in mind, back to the cochlea... given our sense of specific "nerves firing", which we could loosely say is a sense of sound frequencies, "we" can indeed employ "some form of reasoning" to "perceive" that particular kinds of sounds are being made. But that's really what we're doing, not "sensing sound" in the sense you're using the term sense. But this inference would nominally be valid; if a particular "kind of sound" hits our eardrums, then we would have that particular set of nerves firing. But if it works here it works elsewhere; if a particular bird really were there singing, it would result in some particular kinds of stimulus on our retinas and particular kinds of stimulus along our cochlea. A description of just what kinds of effects such a real bird really being there singing would make on these modes of sensory apparatus is very complex, but the "perceptual form of reasoning" can be taken as part of our sensory apparatus just as easily as that hammer, anvil, stirrup, cochlea fluid, and hairs along that spiral can.

We're not really seeing individual objects around us, we are sensing differences in electromagnetic radiation, and using some sort of logic to conclude boundaries between things, and we claim to "see" or "sense" distinct objects. In reality the distinct objects are created by some sort of logical process and are not actually "sensed".

This seems to be a definitions issue to me, and it seems a bit simplistic.

There is sensation, and there is perception, and there is logic. To me, it appears you're attributing perception to logic, but it's very distinct from logic. Logic is something you could sit down and write up in natural language, which can then be scrutinized... the process by which "bird" is presented to you digested as "bird" is not this kind of thing.

The way I use the terms, and there's a reason for it, "perception" is part of "sensation"; so I have no problems saying that you "sense" the bird.

I'm going to attempt to ground this discussion by introducing a few things I've dug up.

Let's start by exploring our already extant (as opposed to speculative) subjective experience of perception; I'll presume your senses are nominal here. Sit still in your chair as you read this and just attend to your experiences. You'll notice you "see" things in front of you, and there's an edge to your visual field. But that space you experience doesn't "stop" there... you have a general sense of that space all around you, extending backwards. I'll draw your attention to this "perceptual space"; the stuff you see is fixed into this space (you can glance around and see things at a distance). The stuff you hear is affixed to it; tactile feelings are affixed to it, and so on. Some internal senses are fixed here as well; you sense "yourself" as being in this space somewhere (for me, I feel that "I" am behind my eyes inside my head). We can, and often do, even cross reference these different perceptual modes according to this perceived space; you might see a bird and hear it, and perceive that the bird you see is making that song... both percepts subjectively feel like they are "in the same place". I'm not sure how far this goes, but this subjective perceived space seems like a type of "glue" of our senses.

With this grounding, you can begin to get a sense from the "inside out" that this space is produced by your mind, if you pay attention to the right phenomena. For example, the McGurk effect suggests that our percepts of phonemes is affected by what we see. Another common experienced cross-sensory illusion is something I'll just call the "rollback illusion" (not sure it has another name)... think of when you're in a vehicle (driving/passenger doesn't matter), and there may be a few larger ones left and right in your field, and you're stopped. Suddenly some of the big vehicles in your peripheral move, but in this particular case you experience not the sight of them moving forward, but the feeling that your own vehicle dropped backwards.

Outside of such subjective surveys, if you look deeply into human vision you'll notice that a lot of the mechanics behind vision can't possibly be "universal" in a "physics" sense; color, for example, is a percept whose "physical" basis is really based on the physics of photopic vision (meaning, vision under the mode where conditions bright enough where we see colors; e.g., vision mediated by cones instead of rods). At a cellular level this is a function of how the three cone types in our eyes respond to light; at a physics barrier level, that in turn is a function of how particular photons have particular probabilities of folding photon-sensitive proteins in our eyes (viz photopsins). From there, the "opponent color process" kicks in (via ganglial cell mediation just beyond "bipolar" cells connected to the cones), forming a color space basis with red/green, blue/yellow, and brightness channels. Even in terms of frequencies of photons we see, for example, there are "metamers"... specific colors produced by distinct spectra... precisely because they wind up having the same effects at this barrier level. Furthermore there are plenty of photons in our environment outside of the visual range; and the division between visible light and non-visible light is a matter of this barrier. So again, we come to the same place... the things we experience are produced.

We could go onto many other topics here, such as the fact that as you move, or when you change your glance, our experiences "edit out" what we see during the move/during jarring/etc; and so on and so on. The evidence is quite clear that our perceptual experiences are constructs in themselves.

That's enough for now... you're asking for quite a bit, but I'll just post this one aspect rather than try to address the whole thing, for the moment.