"Blue" proves the mind isn't material
If were to ask someone to "Define the experience of the color blue" they would likely tell me about light rays, and how a certain intensity of a certain wave of light effects our neurons, and our eyeballs in a way that produces the "experience" of the color blue.
that is only a relational description of what is going on, that doesn't tell me what it is like to see blue, you cannot give me a non-circular description of what it is like to see the color blue.
you can say "blue is the color of the ocean" or "this light activates cones in my eyes" but that only tells me what is happening that doesn't tell me what it is like.
Facts about an experience, do not equate to an explanation of phenomenal character of having that experience.
On top of this, we can experience the color blue, such factors are absent. I can close my eyes and imagine a blue square right now, without the light waves "required".
Thus, the experience of the color blue cannot be reduced down to a particular composition of physical components.
On top of this, when I imagine the color blue, "where is it?" the question seems kind of stupid, I must admit, but it does have implications. When I imagine the color blue, do I see it with my eyes? my eyes only see data from light, but the imagined blue is not coming from actual light. is the experience in my brain? what part of my brain?
If it cannot be physically reduced, nor physically localized, I am led to beleive that it is not physical at all.
I don't think I'm nessecarily making an argument from a gap in our knowledge, atleast not my argument from the irreducability of the experience of the color blue. It can't be defined in a way that isn't circular.