Explaining colour in terms of how objects reflect, refract or emit different wavelengths of light (and similarly for the rods and cones in our eyes) sounds perfectly satisfactory to me. What's the problem with that theory?

I really don't see the point of all the metaphysical stuff. It just doesn't tell you anything useful.

These debates are less about a clear and present problem, than a mode of inquiry asking to look again at something "familiar" in a different way.

In terms of finding the actual answer (at least to the extent that we know the answer), it probably wasn't; but, in terms of suggesting that the question was one that had an answer, I think it was enormously fruitful. Leon Lederman's wonderful book "The God particle" persuasively (if perhaps slightly tongue-in-cheek?) argues a very direct intellectual through-line from the Greek analyses to (then-)current particle physics.

(Having said this, my personal feeling is that philosophy has done its part by expanding the scope of scientific inquiry, but probably doesn't have much to add to modern-day scientific discourse; but, then again, I am a scientist, and so am pre-disposed to believe in the primacy and importance of my discipline.)

At least physically, this seems wrong to me. Temperature is an emergent property of systems—there is no such thing as the temperature of an isolated particle—whereas (as spectral analysis shows) even individual atoms have colour.

  Do you know what it looks like? 
  Can you imagine what it looks like? 
  Can Maxwell's equations predict what it looks like?

The Problem of Color is a subset of the Hard Problem of Consciousness. Both are uncharted territory. Maybe one day we'll have a half-decent theory of color. When that day comes, it will probably bud-off and begin a field of study distinct from "philosophy proper". Just like math and science budded-off. In the meantime, the only thing we can do is imagine and philosophize. Because we don't understand how to even investigate the problem, let alone solve it. We're still at the stage analogous to when the Ancient Greeks were debating whether matter is continuous or discrete. "Nobody knows for sure, but matter sure feels continuous to me."

The least we can do is demarcate our ignorance. Which is why blogposts like this exist. So when you (essentially) say "Our current theory of optics sounds perfectly satisfactory", you are defending the delusion the blogpost meant to correct. My two previous comments aren't meant to contribute a theory of color, but to make obvious that optics and color are not the same thing.

That's a good summary of what the article seems to be saying. But I still don't understand the reasoning behind that claim.

I mean, from the article:

But can this really be right? Focus on a colour in your immediate environment and ask yourself whether that could really be only a figment of your mind, or at best radically different from the way it appears.

Yes, obviously? What's the problem?

Somewhat analogously, there's a whole world of scent and pheromones that most animals perceive strongly, but we barely perceive at all. An entire sense that we don't even realise we're missing! I think that's fascinating, but it doesn't lead me to question the nature of reality in any deep philosophical way. Should it?

The Soft Problem is easy to imagine. Neuroscience will solve it eventually. We may not understand it yet, but we can make a lot of computer analogies and educated guesses. After all, computers are already Philosophical Zombies (someone who passes the Turing Test, yet in no way experiences qualia).

> but it doesn't lead me to question the nature of reality in any deep philosophical way. Should it?

Here's the contention the professionals are currently debating. The Hard Problem challenges our notions of Physicalism (as opposed to say, Dualism). "But souls are dumb, Science says so!".

Extrapolate into the future. Even after Neuroscience solves the brain's circuitry, qualia will remain just as mysterious as ever. E.g. suppose we discover that the hippocampus demultiplexes memories to different parts of the brain. Suppose we learn how to directly manipulate memory. Not only can we fix amnesia, but we can implant false memories. "Hooray, we've solved the Soft Problem!". But we still have no leads on the Hard Problem. A hippocampus doesn't distinguish a Homunculus from a P-Zombie.

Physicalism has been so successful in the sciences, everyone takes its accuracy for granted. I myself consider Physicalism true. But Physicalism is not adequate to explain the Hard Problem. This doesn't mean we have to go back to souls. But it does mean we need to (at least) "spice up" Physicalism, or maybe choose another line of attack, etc if we're ever to crack the Hard Problem.

Neuroscience and computer science obviously haven't solved it either, but they have at least made some progress in understanding parts of the brain's structure, and gradually reproducing what we thought were uniquely human abilities with mindless computer programs. This suggests that "qualia" may not really be needed to explain consciousness (or at any rate thought); just as Darwin's theories showed why "god" isn't strictly needed to explain the diversity of animal species.

I agree there's still the niggling issue of "but why do I seem to experience stuff? Surely I'm not a mindless automaton!" There's also the problem of "but why does the universe exist in the first place?" But I don't believe philosophers have any particular insight or knowledge to bring to the first problem, any more than theologians have any real inside knowledge of the latter.

The problem of qualia comes into play most especially when a materialist metaphysical position is accepted of the kind where the immaterial res cogitans is denied. The materialist is then faced with the task of explaining how all of that which was attributed to minds (e.g., color) -- and indeed minds themselves -- is really something that can be attributed to res extensa. The kicker is, of course, that you can't, at least not without radically reforming how you understand matter. It is by definition impossible to locate color in matter given a Cartesian understanding of matter. Many physicists, in their more philosophical moments, tacitly accept a metaphysical position of that kind.

What's important is that the modern understanding of color, one that attributes it to consciousness rather than things, is not a scientific position. It is a metaphysical position and a very problematic one that is running its course as philosophers and scientists try helplessly and in vain to explain things like consciousness and the objects of consciousness.

Similarly my understanding and perception of the colours I see comes from a real physical body that has accumulated a lot of sensory input and experiences and uses that to interpret new sensory input.

I can't explain to you how I experience the colour blue but I don't need to grapple with metaphysics to explain, in principle, why I might experience it that way.

[0] Another subtlety here is that the brain states having structure isomorphic to something in subjectivity doesn't necessarily make sense. It would on the assumption that everything is 'structural', but that's not an assumption everyone is willing to make. (You can find demonstrations that mathematics and the sciences can only deal in terms of structure, which is why for their practitioners it makes sense to ignore anything non-structural—but this is very different from a demonstration that everything actually is structural.) In that case, in order to create this mapping, we have to create another structure (for instance, a taxonomy of colors names and relationships between colors), and we can configure that structure in a way which is intended to reflect some moments of subjective experience. Now that structure could be potentially be found isomorphic to some evolving brain states, while to say that the subjective experience itself was isomorphic is likely nonsensical.

I am reminded of an essay by Stephen Jay Gould, on the history of preformationism, and the debate over whether the homunculus resided in the sperm or the egg. The idea that a human could be represented by an ordering of simple chemicals was inconceivable at the time.

The idea that physicalism requires a specific physical locus for redness is no more sound than the idea that genetic theory requires human-ness to be located in a specific base on a DNA molecule. Emergent phenomena are real, common, and not, in general, particularly mysterious (though the mind certainly is, at least to me.)

More prosaically, maybe redness is actually localized, as a memory of a sensation. Is there anything more to redness than a comparison to prior sensations?

I have no issue with emergent phenomena. It's just that whether the phenomenon is emergent or not is irrelevant to the question at hand.

For instance, let's say the brain 'system' responsible for color perception is distributed all throughout the human brain in such a way that it would be impossible to formulate any hierarchical conceptual structure which could account for it. It's just an emergent consequence of a ton of other complex stuff going on.

Okay, now if you recall my previous point about reconciling the experience of redness vs clusters of neurons—you can hopefully see that the above makes no difference to the problem. It's just a different mapping of a physical structure onto subjective experience, without accounting for the fundamental difference between the subjective experience and the physical structure.

(This answer is less thorough, but I did take my time with what I wrote previously. If you read it more closely I think you'll see the difference in what we're each talking about here.)

If you insist that there is no difference, then it goes both ways. I think you are actually right in a way you did not intend: more sophisticated versions of the qualia argument are ultimately no better, as at some point, it always comes down to what you are prepared to believe - that there is a fundamental difference that cannot be bridged.

There was a time when humanity found it impossible to believe that life could arise from matter alone, yet dualism in this regard has effectively been abandoned, at least scientifically and philosophically. While this does not, of course, prove anything about the mind, it does show how arguments from the fundamental difference between matter and information-like things are really appeals to plausibility. As an observation that there is a gap in our understanding, that is fine; as a claim that the difference can never be resolved, they are just opinions.

And as I briefly speculated in my last paragraph, the physical basis for color as a quale might be surprisingly localized...

This including any kind of scientific hardware we use to measure it?

How many people believing otherwise would it take to change the experience of matter in general public, if it is subjective? (Because if it is subjective, it must be malleable.)

My teen self would call me a hippy - but you have to follow the logic!

wikipedia:

> Thus, the two kinds of knowledge, justification, or argument, may be glossed:

> A priori knowledge or justification is independent of experience, as with mathematics (3 + 2 = 5), tautologies ("All bachelors are unmarried"), and deduction from pure reason (e.g., ontological proofs).[3]

> A posteriori knowledge or justification depends on experience or empirical evidence, as with most aspects of science and personal knowledge.

There's nothing wrong or controversial about my definition. Non-Experiental Knowledge is Logical Knowledge by exhaustion. "Feeling" is exactly the kind of thing "a priori" was intended to exclude.

> In this sense it is similar to saying that something is axiomatic.

In no sense of the word, colloquial or academic, does "a priori" mean "axiomatic". They are different beasts.

> Besides I'm not at all sure there is a difference between knowledge gained from logic or from experience: <skims youtube video>

The video redefines the Problem of Infinite Regress as "Modus Morons". I've read What the Tortoise said to Achilles myself. Yes, the truth of modus ponens is arguably derived from induction. But that's a topic I'm not going to get into right now. At the very least, the terms are useful to label their disparate track-records.

If you want to dig further, your general position is called Idealism.

You have an argumentative style which implies that you are more interested in winning than seeking the truth. As such I am dissinclined to take you too seriously.

Similarly, suppose scientists discover a neural-structure (or chemical-interaction, etc) responsible for blueness. I can dissect it, electrocute it, soak it in LSD. But will the scientists experience blueness? No, because the structure isn't qualia per se.

The prevailing ideology is that by studying the mechanical nature of coffee machines, we'll ipso facto understand the biochemistry of the beverage. danielam is arguing that this ideology is probably wrong. This is why the Problem of Qualia is a problem.

Second -- and this is not the main thrust of what I said, but it is in response to what you wrote -- you are begging the question when you presume that everything can be accounted for physics. Consider the concept of Triangularity. In the world, we have concrete, triangular things that instantiate Triangularity. We perceive them through our senses. One triangle may be an isosceles triangle, another might be equilateral, still another may be a right triangle. Of these, each may be large, small, drawn with thick lines or quickly sketched on the board with a piece of chalk. However, none of these triangular things are themselves Triangularity or else only one triangle could exist. Furthermore, none of these concrete instances are perfect instantiations of Triangularity. The lines composing them are never fully straight. They are only approximations, and yet we still know what Triangularity is, its properties (like the angles summing to 180 degrees), and so on. It exists in our minds, and in the mind it exists, by necessity, completely apart from any particular, concrete instantiations of it (we may have images of triangles in mind, but the images themselves are not Triangularity itself, something all these images share). It follows that because Triangularity isn’t concrete or particular, there exists in the mind something that isn’t concrete or particular, but universal. But because physical things are necessarily instantiations of universals and not universals themselves, then we have in our minds something non-physical.

What reformation is required here? Given how simulated neural networks tend to end up with particular neurons representing concepts, it should not be surprising if one could find neurons in the brain for colors. The experience of color is the combined effect of activation of those neurons.

This doesn't seem all that bad to me. I'm faced with the task of explaining lots of things that I don't understand for a variety of reasons. Sometimes I'm motivated to participate in the exploration, sometimes I'm willing to let it be delegated to others. This would seem to be true regardless of whether I think that the mind is material or immaterial. We may develop an elaborate theory of the immaterial mind, yet end up concluding that we still don't understand color.

I wouldn't trust myself to conduct research into the inner workings of an immaterial mind, without perhaps building up from a successful inquiry into simpler immaterial systems.

My guess though is, to your point about qualia, while we've scientifically categorized animals, plants, and minerals food is fairly subjective but many preferences are shared between people. We've also developed a rough language around food (sweet, sour, umami), and food scientists have studied it and tried recreating characteristics.

Yes, of course that could really be the case. It's a bit of a downer that this article ends with an argument from incredulity.

Nobody perceives reality as it actually is. It’s all just vibrations in various fields, and any macroscopic interpretation above that is your imagination, from your own personal identity to the colors you see.

EDIT: I did find this review, but I haven't read it[0].

[0] http://ndpr.nd.edu/news/a-naive-realist-theory-of-colour/

Indeed, and I have this nagging feeling that there might be something to it. It goes along with the suspicion that neither what I perceive through my senses nor what I apprehend through my intellect are as coherent as they feel, but perhaps that's just me.

A couple of comments: This sentence has a misleading form. It sounds like "Nobody here has a hat", denying something quite unproblematically possible. But would would it mean to perceive reality 'as it actually is'? The phrase seems confused. Like people who worry about life being meaningless, there's a category error being made somewhere.

And the phrase 'reality as it actually is' is but a modern version of the Kantian 'reality as-it-is-in-itself', (of which nothing could be known or said). Some of the problems coming from such language (i.e. most of Idealism and relativism in their various forms) and their history have been entertainingly explored by the philosophers Musgrave[0] and Stove[1].

e.g. "We can eat oysters only insofar as they are brought under the physiological and chemical conditions which are the presuppositions of the possibility of being eaten. Therefore, we cannot eat oysters as they are in themselves."

or "We have eyes, therefore we can't see."

[0] Alan Musgrave, Idealism and Antirealism http://www.phil-fak.uni-duesseldorf.de/fileadmin/Redaktion/I...

[1] Stove's Discovery of the Worst Argument in the World http://web.maths.unsw.edu.au/~jim/worst.html

It would mean that direct perception is the case. We directly perceive the objects out there in the world as they are, not a representation of some sort in our heads.

> We have eyes, therefore we can't see.

It's more like, we have eyes that provide our brains with information to color in the world in response to visible light reflecting off objects.

But that doesn't answer the question about whether the world is actually colored. What if we had a different kind of eyes, or our visual cortex processed the information differently?

Is only the visible light colored, or do radio waves have colors, or is the color on the surface of objects themselves?

My point was that this is a grammatical sentence, but like a christian talking of eternal life, the impossibility and unimaginability of the thing is ignored.

That bit about the eyes was a TL;DR and teaser for the linked (very funny) papers, which doesn't mean much without them I guess. It's a spoof/reductio of a kind of argument which has often been used in philosophy, Stove's Gem. Yes sorry, not answering questions. I seem to spend more time questioning questions. They often conceal and smuggle in false assumptions.

I'm not personally outraged by the casual manipulation and instrumentalisation of that painting by some graphic designer -- it is in the public domain -- but it seems like a very unprincipled and ignorant thing to do. The title of the painting is "Altar Painting, No. 1".

> Featured image credit: Altarpiece, No. 1, Group X, Altarpieces by Hilma af Klint. Public domain via Wikimedia Commons.

> For it is of four colours, and takes its appearance from all of the elements into itself. From the sky it draws the fiery colour, from the waters purple, from the air white, and from the earth it gathers black.

Source: https://forthewynnblog.wordpress.com/2017/11/20/how-many-col...

But purple and violet are truly fascinating, the way they help construct a circular color wheel when there is nothing circular about color spectrum.

Take a look at the LAB color model. It's defined with three axes; lightness, green–red and blue–yellow.

Yellow has no special meaning in this model.

(The LAB color model also originates from physiological considerations, but on the neurological level, i.e. at least one step after the color receptors.)

(Except for the tetrachromatic 2%, who experience a 4th primary color where "yellow" ought to be.)

While you could try to engineer a more efficiently yellowness-detector, engineering a better magentaness-detector would be a qualitatively different kind of biological machine.

Suppose humans experienced 12 primary colors. Is a combination of the 2nd, 5th, 6th, and 12th "on the spectrum" any more than an exclusive combination of the 2nd and 3rd?

What's interesting is differences in the MINIMAL set of physical things that need to be detected to get the experience.

The objective truth is that if I hand you a machine that generates just single wavelengths of photons, you can cause "Normies" to say "yellow" but you can't do the same for "magenta".

That asymmetry remains even when you talk about adding more sensors. You can frequency-shift an R/G/B cone to get a new kind that "peak-triggers when normal people say yellow" but you cannot do the same to create one which "peak-triggers when normal people say magenta". You would need to create a fundamentally different kind of sensor.

Mirimir wouldn't feel surprised about the absence of purple if they understood color in the context of phenomenology (rather than engineering), which is the spirit in which the post was made.

I understand the difference you are pointing to. It's not a novel or interesting position, it's the default position. If you insist on binding colors to wavelengths, you probably didn't get anything out of the blogpost.

This is important because privileging magenta does not generalize to higher-dimensional color-spaces, and therefore impedes to our understanding of phenomenology.

E.g. a "yellow" wavelength is only as bright as its decomposition into red and green. The fact that red & blue aren't adjacent is a red herring.

> Focus on a colour in your immediate environment and ask yourself whether that could really be only a figment of your mind, or at best radically different from the way it appears.

That question, which seems to be the bottom line on color before moving to the even more problematic broadening of the issue in the conclusion, is quite lazy; the answer is self-evident yes, and that's true even for traits that the article notes fundamentally do apply to objects (like shape), as anyone who has ever looked through a distorting lens or mirror (or had a visual hallucination) can readily attest.

He “problem”, such as it is, of color is not that a color one perceives might be different from the actual color of the object, but that color is not a property of objects at all, but instead an artifact of compressing information carried by the wavelengths of light impacting the eye to a smaller-dimensonal space, and that even the wavelengths of light that will be received is not purely a trait of the object perceived, but an effect of the combination of several of its traits with features of the environment. But, of courses this isn't a problem for anything out a particular preference for the nature of reality, it's just a well-established fact. At some point our model of reality must be adapted to known facts rather than merely reflecting what we'd prefer to believe.

The ultimate conclusion of the piece goes even further off the rails.

> Moreover, colour is arguably only the thin end of the wedge. One of the reasons why colours are philosophically interesting is that they provide an illustration of general problems that arise in thinking about the “manifest image” of the world, or the world as it appears to us as conscious subjects. It is not just colours that are under threat. Similar problems arise for aesthetic properties like beauty

That beauty is not an inherent property of objects but a subjective response of the observer has been indisputable and widely recognized for much longer than the same is true for color, so that’s a ludicrous thing to point to when claiming color is the thin edge of the wedge.

> for moral properties like right and wrong

Well, yes, this is the philosophically most interesting one, and it's worthy of discussion, but this piece doesn't even begin to be that discussion, or even indirectly illuminate the issue.

> —even for what philosophers have traditionally called “primary qualities” like shape and size.

Well, sure, somethingnsimilar applies there, though the problem there is somewhat different, and connects to the more fundamental problem that the objects to which we apply traits aren't fundamental entities, but arbitrary and subjective divisions of the underlying reality.