A post by Tufan Kıymaz.

Mary is a super-scientist who knows all facts about human visual experience that are expressible in physical/functional terms; however, she has never seen colors since she lives in a black-and-white room. If physicalism is true, then her physical/functional knowledge is complete knowledge about human visual experience. One day, she leaves the room, sees a red tomato and exclaims “So, this is what it is like to see red!” She learned a new fact, which means that her physical/functional knowledge was not complete knowledge, and therefore physicalism is false. This is Frank Jackson’s (1982, 1986) knowledge argument against physicalism.

Some philosophers, such as Churchland (1985:25), Maloney (1985:36), and Dennett (2007), interpret this argument to be about Mary’s inability to imagine red while she was in the room. However, Jackson writes:

the knowledge argument claims that Mary would not know what the relevant experience is like. What she could imagine is another matter. (Jackson 1986: 295, also see 292)

… So, the interpretation of his argument by the objectors, which states that Mary’s inability to imagine what it is like to see red implies that physicalism is false, is a strawman. Let’s call this strawman “the imagination argument.” As far as I can see in the literature, the imagination argument is criticized and rejected but I have never seen an explicit defense of this argument. In my paper “What Gary Couldn’t Imagine” (2019), I presented the most powerful version of the imagination argument that I can think of and evaluated its strengths and weaknesses. I believe that the imagination argument deserves more attention than it has received so far.