[KingMob]

You've completely left out the Hard Problem, though, and missed the essay's point.

A large part of the essay is that we have plenty of objective knowledge about how bat sonar works, but we don't know what the subjective experience of sonar is like, and more importantly, knowing about the physical representation, whether in neuronal patterns or embeddings, doesn't get you closer to the subjective experience.

tl;dr RGB(1.0, 0.0, 0.0) !== the subjective experience of red.

[HarHarVeryFunny]

No - he's right - it's all relative. Our experience of a color is based on recall of things of that color.

Experimentally it's been shown that if a subject wears color goggle then initially everything will appear color tinted, but after a while normal color perception returns. The quale of "red" is not some absolute thing related to the wavelength (hence neural inputs) of red light.

[KingMob]

> Our experience of a color is based on recall of things of that color.

You're getting memory mixed up with current experience. I think you mean to say that experience is based on the neural substrate associated with a color (mostly area V4 in human brains, which causes achromatopsia when damaged bilaterally).

(If memory is mandatory, then infants wouldn't see color when they first open their eyes, which seems unlikely. It also implies that cerebral achromatopsia would be impossible; but the damage that causes achromatopsia is in primary visual cortex, not memory areas.)

---

But again, this misses the point. The RGB triplet is a fact known about the color, but knowing 100% of the facts of the representation does NOT tell you what it is like to experience red.

Consider a perfect future neuroscience lab that uses nanomachines to safely record every neuronal firing, every dendritic voltage shift, every synaptic cleft's neurotransmitter levels, all at microsecond precision, while showing you red circles. This lab knows everything about what your brain does in response to red stimuli. Everything EXCEPT the subjective experience of redness in the participants.

[HarHarVeryFunny]

An infant's perception of the world, in the days/weeks/months following birth is not going to be like our own until they have indeed started to form memories/associations of things outside of the womb (where the main color they will be exposed to is red - light filtered through the mother's stomach). Even after birth it's going to be a while (depending on parents/environment) until they have much exposure to certain classes of things, maybe even certain colors (e.g. an indoor baby may not be seeing a lot of green).

RGB triplet has little to do with color vision since we don't have sensors for individual wavelengths - our color cones (most people have 3 types, but some have 4, allowing them to distinguish a lot of spectra that a normal person can't) all have broad gaussian responses and so all respond to all wavelengths, just with different spectral sensitivities.

An infant who first opens their eyes, or is exposed to new colors for the first time, is not going to have the same experience of color as later on, but necessarily there will still be some experience of "color" (e.g. a varying surface attribute, differing by the different neural inputs coming from the retina), but the subconscious associations will of course be different - something is not going to be perceived as "grass green" or "sky blue" until you have experienced those.

Of course you can never know the subjective experience of another person, let alone another animal, since while there will be a lot in common, dictated by brain architecture, it's also going to depend on individual experience. Our senses work by prediction, which is based on personal experience. If you look at a mid-game chess board you are not going to see the same thing as a grandmaster since they will be seeing positions and you will just be seeing pieces.

The real point is that the subjective experience of a color like red is not some absolute thing tied to the neural inputs for "red" (i.e. varying strengths of signal firing from your 3/4 wavelength sensors), since the experience is the same even when those inputs change - color constancy, goggle experiment, etc etc.

[KingMob]

You are still missing the point, and talking about everything BUT the disconnect between objectivity and subjectivity. I don't know how many times I have to mention the Hard Problem in the comments before people address it in their responses.

Yes, subjective experience is unique, based in neural architecture, color-blindness, experience, etc, etc etc. All of that is irrelevant to the essay.

> The real point is that the subjective experience of a color like red is not some absolute thing tied to the neural inputs for "red", since the experience is the same even when those inputs change

Not the real point of the essay at all. Please, just go read up on the Hard Problem.

[HarHarVeryFunny]

That's not really what Nagel is talking about - the paper is about the difficulty, if not impossibility, of using reductionism to explain some things such as subjective (conscious) experience.

Note that at the beginning of the paper Nagel says "Conscious experience is a widespread phenomenon. It occurs at many levels of animal life ...". His starting point is a willingness to accept that higher order animals are indeed conscious, and that by extension it is indeed like something to be them.

If you want to discuss the hard problem, then you are talking about the wrong paper, and should be reading Chalmers (or Kirk's earlier "Zombies v. Materialists") not Nagel. However, Nagel is of course right, and the p-zombie is a non-sensical construct. If you have a sufficiently advanced cognitive apparatus then of course you can reflect on your own mental life - of course it "feels like something".