 Another doubt about the thought experiment is raised by the claim that a person who is confined to a monochromatic environment but knows everything physical there is to know about visual color experience would be able to figure out what colored things look like and thus would e.g. be able to imagine the kind of color experience produced in normal perceivers when looking at the cloudless sky during the day (see e.g. Dennett 1991; Dennett 2007; Churchland 1989; Maloney 1985, 36). Probably the most common reaction to this is simply to doubt the claim. But it is not clear that the claim, if correct, would undermine the knowledge argument. The opponent would have to show that complete physical knowledge necessarily involves the capacity to imagine blue. One may doubt that this claim is compatible with the widely accepted assumption that physical knowledge can be acquired independently of one’s particular perceptual apparatus. (Arguably a subject whose visual apparatus is not suited for visual experiences at all will not be able to develop the capacity to imagine colors on the basis of physical knowledge alone, even if this were true for Mary).