Ginkgo wrote: I think there is something slippery about the physicalist argument when they claim it is possible for Mary to emerge from her room with all the information about colour and simply say, "Nah... I knew what red was like all along."
Thanks for the link, Ginkgo. This is the bit I was really interested in: "Dennett argues that functional knowledge is identical to the experience..." On the face of it, it is a ludicrous claim, I'll have to check out how he develops such an argument. I'm sure you have seen me blabbing on about how phenomena are the only things we can be sure exist; why we need 'qualia' is a complete mystery to me.
Having said that, it is fairly evident that we don't simply 'see' what the apparatus of the eye enables us to, and that there is quite a lot of interpretation done by the brain. I read 'Through the Language Glass' by Guy Deutscher recently; it's a brilliant book and makes a compelling (to me at least) argument for some form of linguistic relativity. It closes thus:
"It has been shown, for example, that long term memory and object recognition play an important role in the perception of colour. If the brain remembers that a certain object should be a certain colour, it will go out of it's way to make sure that you really see this object in this colour. A fascinating experiment that demonstrated such effects was conducted in 2006 by a group of scientists from the university of Giessen in Germany. They showed participants a picture on a monitor of some random spots in a particular colour, say yellow. The participants had four buttons at their disposal and were asked to adjust the colour of the picture by pressing the buttons until the spots appeared entirely grey, with no trace of yellowness or any other prismatic colour left. Unsurprisingly, the hue that they ended up with was indeed neutral grey.
The same set up was then repeated, this time not with random spots on the screen but with a picture of a recognisable object such as a banana. The participants were again requested to adjust the hue by pressing buttons until the banana appeared grey. This time, however, the actual hue they ended up on was not pure grey but slightly bluish. In other words, the participants went too far to the other side of neutral grey before the banana really looked grey to them. This means that when the banana was already objectively grey, it still appeared to them slightly yellow! The brain thus relies on its store of past memories of what bananas look like and pushes the sensation of colour in this direction."
I think I would be a bit more circumspect about reaching such a conclusion, but it does make you wonder if there is any such thing as an objective qualia, and whether Mary, being used to seeing 'grey' apples would actually see them as red at all.