See my update below. > The author has to prove that this mapping exercise is indeed not new knowledge... Is that what you meant to write? It seems that "the a

See my update below. > The author has to prove that this mapping exercise is indeed not new knowledge... Is that what you meant to write? It seems that "the author" here is referring to the paper's author (Frank Jackson), but his whole argument depends on the premise that the result of this mapping exercise is new knowledge. It is acceptable English usage to call what Mary learns on release "knowledge", but it is not knowledge in the form of a proposition that you believe to be true; it is the memory of an experience (and whatever connections are made from that experience), and materialism does not claim or imply that you can gain the latter from reading it in a book. --- Update: With respect to the phrase I quoted, I see what you mean. This knowledge (if that is what it is) is new to Mary, but unless it existed and was knowable before Mary was released, the argument fails to show some knowledge that Mary did not know then but was knowledge at the time. Jackson attempts to get around this by saying that she learns something about other people - specifically, that her conception of the mental life of other people was incomplete before her release and more complete after. Insofar as that conception includes objective facts, however, Mary could know those facts beforehand. Seeing colors might modify her personal justification for believing those facts (along the lines of "previously, I accepted it on the basis of what I learned verbally but now I accept it on the basis of my experience"), but note the "my experience" in that phrase: those experiences did not exist until after her release, so this justification was not available to Mary beforehand.