[ducharmdev]

It's odd to me that you chose color as an example of something objective, since so much about perception is subjective.

Even if we think about it in more quantitative terms, with red being defined as having a dominant wavelength approximately 625–740 nanometres, it's a bit of an arbitrary definition isn't it? If we observe a wavelength of 624, objectively we might say it's not red, but someone may still observe it as red considering how close it is to red. Or someone with protanopia won't see anything in those bounds as red either.

[beezlebroxxxxxx]

Color relies on ostensive definition. It's a public part of language whether someone is color-blind or not. When we say "that car is red" we are, in a sense, pointing to something and then using the concept and rules of color in our language. We might see something as a particular color through perception, but when we see "that --->" we are, in a sense, "seeing" in language (including body language, for instance. You could ask me which one is red and I could simply point).

We, of course, might disagree, but color-blind people learn which traffic lights are red, green, or yellow, regardless of their perceptual faculties. Because the color is not just what you see, but what you say.

[ajuc]

I use f.lux - it changes the screen color temperature through the day to make it easier to sleep.

If I sit late at night my desktop walpaper (which is a regular photo with a lot of blue sky) becomes basically all red if you look at rgb values. But I still perceive the sky in it as blue because other things are "more red" so it looks blue, and because I know sky is blue, and because I remember how it looked before and the change happened slowly.

All of these scream "relativism" to me, in fact the mapping to common moral fallacies is surprisingly direct :) When law changes around you you might not recognize when it got evil. Obeying the law is good because it's the law. When everything around is evil - small evil seems good.

As for language and law - these are arbitrary. "Yellow pages" can be any color, so can "blue screen of death". Green traffic lights are actually blue in some countries.