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Lumifer comments on Green Emeralds, Grue Diamonds - Less Wrong Discussion

8 Post author: Stuart_Armstrong 06 July 2015 11:27AM

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Comment author: Lumifer 18 July 2015 03:53:11AM *  1 point [-]

We would run into the same problem for any description of a quale/sensation.

Only if you decide you're defining a sensation and not some physical phenomenon.

The highly contextual nature of color perception is ubiquitous. Human color processing is always making contextual adjustments from scene illumination.

Yes, I understand that very well. But all that tells you is that different definitions will diverge in many cases.

Also, don't you mean objective?

"Subjective" was probably the wrong word. I distinguish:

  • A physical approach which defines color through spectral power distributions

  • A human objective approach which defines color via the tristimulus model (the CIE color space, etc.)

  • A human subjective approach which defines color as a particular perception

The human subjective approach has -- as you have pointed out -- all the issues associated with talking about subjective sensations, that is, they are essentially unobservable and it's very hard to get a good handle on them. That, to me, makes defining color through qualia a definition that isn't useful all that often.

Comment author: isionous 22 July 2015 04:20:14AM 1 point [-]

Only if you decide you're defining a sensation and not some physical phenomenon...That, to me, makes defining color through qualia a definition that isn't useful all that often.

That's the definition used in the overwhelming majority of cases. Careful, technical texts often make it clear that color is a sensation. Even Isaac Newton stressed that "the rays [of light] are not colored".

Even wikipedia goes with the sensation definition of color: "Color...is the visual perceptual property corresponding in humans to the categories called red, blue, yellow, etc...The color of an object depends on both the physics of the object in its environment and the characteristics of the perceiving eye and brain."

In everyday use, when a person says things like "hand me the blue towel", that person usually does not care, know, or even think about reflectance profiles and spectral power distributions. Usually all that person cares about is that the towel "looks blue" to him and the person he's talking to. He'll say "that towel is blue" just like he'll say "that chocolate is bitter".

It's very useful to have definitions that depend on human sensations. You and I are both humans, and we often have conversations with other humans.

Comment author: Lumifer 22 July 2015 04:26:08AM 2 points [-]

That's the definition used in the overwhelming majority of cases.

I do not believe that to be so. An example: all color management in digital photography. Another example: color swatches (e.g. Pantone).