Frank Jackson, in his essay Epiphenomenal Qualia, proposes the knowledge argument. It is a philosophical thought experiment to argue against Physicalism, the notion that all that is mental is entirely physical. Therefore, Jackson argues that there are aspects of mental consciousness that cannot be fully explained by the physical nature of the brain. In this thought experiment, Mary, a brilliant scientist, has been kept prisoner since birth in a black and white laboratory. She has lived and worked through having to learn about the world from a black and white screen, and knows everything physical there is to know about the brain and color. Jackson theorizes that if Mary experiences color first-hand by leaving the room, or by obtaining a screen that uses color, she will learn new information. Mary is then let out of her laboratory for the first time, experiences color, and is surprised. Before she was released, Mary had lacked knowledge about human color that she later gained once she had experienced color first-hand, proving that not all knowledge is found within physical knowledge and Physicalism false.
Jackson's thought experiment presents a problem for Physicalism because it disproves the philosophical view. According to Jackson, Mary knowing all there is to know physically about the brain is not the same as having experienced the things that cause all the brain states she understands. Meaning, seeing color up close and in person is the only way to experience color and obtain new knowledge beyond what is known physically. Jackson's argument is that Mary learned new information through the new life changing experience of witnessing color, proving Physicalism is wrong. Jackson states: "It seems just obvious that she will learn something about the world and our visual experience of it. But then it is inescapable that her previous knowledge was incomplete. But she had all the physical information.