Perhaps. But do you see how naive realism is foundational?

Perhaps. But do you see how naive realism is foundational? — Banno

Yes. And Philosophy began (at least in part) by challenging that foundation.

Sure. The blue colour of the sky is caused by the selective absorption of red, green, yellow and so on in the atmosphere. What would be wrong would be to conclude from this that the sky is not blue, or that colours do not exist.

The table is made of wood; therefore there is no table, only wood.

Would you agree with this?

The table is made of atoms which are mostly space. Therefore there is not table, only space.

The sky is the selective absorption of certain wavelengths of light. Therefore there is no sky.

Colours are differing electromagnetic frequencies. Therefore there are no colours.

Colours are just the result of differential firing of the rods and cones in your eye. Therefore there are not really any colours.

Edit:
The first example is obviously false. The other examples have the same structure, and hence are also false.

So, to explain my joke, there are colours.

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 couldn't have said it better myself!

|>ouglas

Do colours exist? Yep.

Therefore there are not really any colours.

Can you phrase the question so it is clear it is about the second answer?

Sounds like you might know such 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?

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!

The table is made of wood; therefore there is no table, only wood.

Would you agree with this?

The table is made of atoms which are mostly space. Therefore there is not table, only space. — Banno

I would tend to say the table is a collection of molecules arranged table-wise. Ordinary objects don't exist quite as we think they do (yes, I'm hedging a little bit here).

The sky is the selective absorption of certain wavelengths of light. Therefore there is no sky. — Banno

There's an atmosphere, or collection of gas molecules several miles thick around the Earth.

Colours are differing electromagnetic frequencies. Therefore there are no colours.

Colours are just the result of differential firing of the rods and cones in your eye. Therefore there are not really any colours. — Banno

Colors, in terms of our experience of color, are correlated with visual brain states, somehow. The rest is a causal story of how visual perception works.

Mommy, I want the little brown puppy.

But honey, there are no brown puppies.

Humans are not the only creatures capable of seeing color. Camouflage wouldn't quite work as an evolutionary advantage if there were no color...

It's just ridiculous. If 'science' can't square with simple everyday facts... then 'science' is using the wrong linguistic framework.

Colors, in terms of our experience of color, are correlated with visual brain states, somehow. The rest is a causal story of how visual perception works. — Marchesk

So take this to the final step... is your conclusion that colours do not exist?

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.

...humans are the only ones that see "red", "green", "yellow", "blue", "brown", and other colors humans talk about. — InPitzotl

That's not true.

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.

Animals can be trained to select red things.

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).

They are picking out red things.

Are they not?

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.

Curious. Are you saying that colors do not exist?

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.

Ok.

Then what's at stake between your position and my own is a matter of degree and not kind, so to speak.

Some animals are red/green color blind. Dogs... I think?

Others are not. Some can sense/detect infrared, others ultraviolet.

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

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.

Colors exist because different light frequencies exist. Your cell phone interprets different frequencies as different signals. Even time modulation and frequency hopping spread spectrum does use FM to some extent.

So our eye balls interpret different frequencies as different colors. Colors exist.

Are there true sentences involving colors as objects of them? If so, then colors exist. — Pfhorrest

Thats fucking funny. You are correct Sir.

Spectra and colors...

What's the difference?

So take this to the final step... is your conclusion that colours do not exist? — Banno

They don't exist as objective properties. But they do exist in the same way anything subjective or mind-dependent exists. I take the question to be an ontological one, and therefore colors don't have a mind-independent, real existence, anymore than hallucinations, thoughts or dreams do.

It's like asking whether pain exists. Yes, as a sensation it certainly does. But no, it doesn't exist independent of organisms that experience pain.

It's just ridiculous. If 'science' can't square with simple everyday facts... then 'science' is using the wrong linguistic framework. — creativesoul

Or common sense is just plain wrong, as it has often been shown to be the case. After all, if science disagrees with the obvious fact that the sun moves across the sky, the Earth is stationary, and the table is completely solid, then obviously it's using the wrong language when it says the earth is a sphere in motion and tables are mostly empty space, right?

Or the sky is water held up by the firmaments. Why else would it look blue?

Are there true sentences involving colors as objects of them? If so, then colors exist. — Pfhorrest

"The sky is blue."

Obviously true, right? Well hold on there

We know there's a lot more eletromagnetic radiation in the atmosphere than what we can see. If we could see it, what color would the sky look like? Most likely not the clear blue we see.

So it can't be simply true in the objective sense. It can only be true for animals with vision similar to ours.