What Mary Didn't Know
Mary lives in a black and white room. She has never seen any color.
She is educated through reading black and white books, and watching lectures on a black and white television screen.
Mary becomes a brilliant scientist: she has, in fact, complete physical knowledge of the world. She specializes in human vision and knows all the physical facts about color experience.
At some stage she leaves her black and white room. For the first time in her life she sees colors. She learns something new. She learns how colors look like. She learns what it's like to see in color.Therefore, there are non-physical facts about color experiences.
Therefore, physicalism is false.
"there are non-physical facts"
RispondiEliminaIt's difficult enough to establish what a fact 'is' let alone attribute physicality/non-physicality to it...
The crux of this thought experiment seems to lie in the implicit assumption that learning is a non-physical process. I would say that this is simply not true.
Brain structure can change due to external factors. Going through 34 months of training to get 'the knowlege' results in a cabbies brain being bigger compared to an average human.
http://www.pnas.org/content/97/8/4398.full
Also, how is Marys knowledge of colour any different from her knowledge of the workngs of the human eye (asides from the obvious)? She uses her senses and intellect to interperate her lectures to build a model in her head. When she goes outside, her brain does that for her, bypassing intellectual engagement. It doesn't matter if the red you and I see are one and the same colour (qualitatively), what matters is that our physical bodies are equipped to detect, and our brains wired to decrypt the information flooding into our eyes in the form of photons. The cabbie example suggests that this recognition surely brings about a physical restructuring of Marys brain, although perhaps to a lesser extent than in the cabbie...
So if knowledge/facts are held in the brain, and putting them there changes the structure of the brain, it's not to big a stretch to suggest that these facts are in fact now part of the brain. This would imply that facts held in one's mind/brain are actually physical.
Of course, this argument is wooly to say the least, but I'm not sure one can get away with the statements and assumptions made in the last chunk of text!