 A third response is to distinguish between various conceptions of the physical. We saw above that potentially the class of properties defined by the theory-conception of the physical was distinct from the class of properties defined by the object-conception. But that suggests that the first premise of the argument is open to interpretation in either of two ways. On the other hand, Jackson’s thought experiment only seems to support the premise if it is interpreted in the one way, since Mary learns by learning all that physical theory can teach her. But leaves open the possibility that one might appeal to the object-conception of the physical to define a version of physicalism which evades the knowledge argument.