||The knowledge argument against physicalism centers on the claim that complete physical knowledge does not enable knowledge of consciousness. In Frank Jackson's formulation, Mary is brought up in a black-and-white room and learns the complete neuroscience of color processing in humans, but she still does not know what it is like to see red: she learns a new fact about color experience when she leaves her room and sees red for the first time. Jackson argues that Mary knows all the physical facts but not all the facts about color experience, so some facts about color experience are not physical facts. Physicalists have replied in many different ways. Some argue that Mary gains an ability without learning a new fact. Others argue that she gains acquaintance with a property without learning a new facts. Others argue that she learns a fact she already knew under a new mode of presentation.