Well I hope you read something about Frank Jackson lol. Actually, if you know about him and physicalism, the rest should flow.
He is basically arguing against physicalism, which propose that everything in our experience is physical (So many precisions should be done here). His argument is called the knowledge argument, which is, if I am not mistaken, the example of a girl in a room which could only see things from a black and white perspective while being able to use concepts such as ''red'', ''blue'' and ''green'' since she had all the empirical information about the spectre of colours we have to distinct them. This girl can call something ''red'' or ''blue'' not based on the visual distinction, but from the empirical evidence that light is a spectre from which you only see a small portion. You can ''measure'' light and know its colour that way. She knows how the light reflecting in her eyes sends a particular signal to her brain before being expressed in word such as ''blue''. We could say that she ''knows'' what blue is.
What happens then if we get that girl outside this black and white room? When she will experience the actual colour, when she will see what she called ''blue'' all that time, can we say that this is different from when she first thought she knew what blue was? Could we even say that its more than what she used to thought it was? Its as if when she was in the black and white room, a part of the phenomenological world could not be accessed.
When he talks about qualia, he refers to the conscious experience. How we experience things in a subjective perspective. What he says is basically that physicalism is insufficient to describe the human experience. His example tries to show how even with empiric knowledge of something like a colour, we can not say that when the girl in the black and white room experienced the colour blue, it was the same way we normally do. Theres something in the human experience that seems to be more than empirical. The qualia (conscious experience) can not be captured by physicalsim.
All this being said, this question requires a lot of concepts that need to be understood in a particular context. This must be understand phenomenologically. Jackson is NOT saying that theres such a thing as dualism of substances as hes only referring to how things are presented to us. All he is saying is that in the human experience, knowledge by acquaintance and knowledge by definitions are insufficient. There are non-physical properties to our experience that cant be expressed and communicated and therefore, physicalism falls short on that matter.
Hope that helps
e/ And this where I notice that op was posted 2 weeks ago. Well, I wont delete that wall anyway lol.
This post was edited by Boblacolle on Dec 5 2013 09:30pm