Standard responses to the knowledge argument grant that Mary could know all of the physical facts even while trapped inside her black‐and‐white room. What they deny is that upon leaving her black‐and‐white room and experiencing red for the first time, Mary learns a genuinely new fact. This paper develops an alternate response in a grounding physicalist framework, on which Mary does not know all of the physical facts while trapped inside the room. The main thesis is that Mary does not (...) know certain phenomenal facts while trapped inside the room, whereby these facts classify as physical due to being wholly and fully metaphysically grounded in the underlying fundamental facts which are themselves entirely physical. (shrink)