http://esr.ibiblio.org/?p=1192#more-1192
ADDED: Even if you disagree with ESR's take, and many will, this is the clearest definition I have seen on what qualia is. So it should present a useful starting point, even for those who strongly disagree, to argue from.
It was about the effect that actually seeing the color red had on Mary's brain. As opposed to learning about the color red from other sources. His claim was that there was something that could only be learned about the color red by actually seeing it, and that was the effect seeing it has on your mind.
That's the issue. I don't think you learn something about the color red; I think you learn something about your mind. There is no objective thing that red looks like; it is the result of certain neurons firing. If Mary's brain were wired differently, the experience of seeing red light would be different if it even existed. The only relevant thing about red light is that it stimulates certain neurons; if you knew absolutely nothing about it except that, you could full... (read more)