Abstract

In 'Jackson on physical information and qualia' Terry Horgan defended physicalism against Frank Jackson's Knowledge Argument by raising what later has been called the 'mode of presentation reply'- arguingthatthe Knowledge Argumentis fallacious because itsubtly equivocates on two different readings of 'physical information'. In 'Mary, Mary, quite contrary' however, George Graham and Terry Horgan maintain that none of the replies against Jackson has yet been successful, not even Horgan's own 1984 rejoinder.Tosubstantiate their claim, they present an allegedly improved version of the Knowledge Argument, the 'Mary Mary Argument' whose default moral is property-dualism. In section 1, I will set the scene by making some clarifying remarks regarding Jackson's original argument. In section 2, I will consider several objections to the most promising physicalist rejoinder to the Knowledge Argument, the mode of presentation reply. In section 3 I will discuss the Mary Mary Argument and propose the indexical account of consciousness that, as it happens, is based on Horgan's own 1984 account as a possible solution. Finally,in section 4, I will argue that to the extent that the Mary Mary Argument exceeds the force of Jackson's original challenge it coincides with Joe Levine's Explanatory Gap Argument