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Don't worry, this sequence of increasingly annoying posts is almost over. But I think it's desirable that we try to establish, once and for all, how people here think color works, and whether they even think it exists.

The way I see it, there is a mental block at work. An obvious fact is being denied or evaded, because the conclusions are unpalatable. The obvious fact is that physics as we know it does not contain the colors that we see. By "physics" I don't just mean the entities that physicists talk about, I also mean anything that you can make out of them. I would encourage anyone who thinks they know what I mean, and who agrees with me on this point, to speak up and make it known that they agree. I don't mind being alone in this opinion, if that's how it is, but I think it's desirable to get some idea of whether LessWrong is genuinely 100% against the proposition.

Just so we're all on the same wavelength, I'll point to a specific example of color. Up at the top of this web page, the word "Less" appears. It's green. So, there is an example of a colored entity, right in front of anyone reading this page.

My thesis is that if you take a lot of point-particles, with no property except their location, and arrange them any way you want, there won't be anything that's green like that; and that the same applies for any physical theory with an ontology that doesn't explicitly include color. To me, this is just mindbogglingly obvious, like the fact that you can't get a letter by adding numbers.

At this point people start talking about neurons and gensyms and concept maps. The greenness isn't in the physical object, "computer screen", it's in the brain's response to the stimulus provided by light from the computer screen entering the eye.

My response is simple. Try to fix in your mind what the physical reality must be, behind your favorite neuro-cognitive explanation of greenness. Presumably it's something like "a whole lot of neurons, firing in a particular way". Try to imagine what that is physically, in terms of atoms. Imagine some vast molecular tinker-toy structures, shaped into a cluster of neurons, with traveling waves of ions crossing axonal membranes. Large numbers of atoms arranged in space, a few of them executing motions which are relevant for the information processing. Do you have that in your mind's eye? Now look up again at that word "Less", and remind yourself that according to your theory, the green shape that you are seeing is the same thing as some aspect of all those billions of colorless atoms in motion.

If your theory still makes sense to you, then please tell us in comments what aspect of the atoms in motion is actually green.

I only see three options. Deny that anything is actually green; become a dualist; or (supervillain voice) join me, and together, we can make a new ontology.