 A third argument for Russellian monism is based on the claim that Russellian monism provides a plausible response to anti-materialist arguments such as the conceivability argument and the knowledge argument (see the entries  zombies  and  qualia: the knowledge argument  and Alter 2017). The conceivability argument is often formulated in terms of a zombie world (Chalmers 1996): a physical and functional duplicate of the actual world but without consciousness. It is first argued that a zombie world is ideally conceivable, which means roughly that such a world cannot be ruled out as incoherent by a priori reasoning (Chalmers 2002). It is then argued that the ideal conceivability of such a world entails its metaphysical possibility. Finally, it is argued that the metaphysical possibility of such a world entails that physicalism is false. The knowledge argument begins with Frank Jackson’s (1982, 1986, 1995) case of Mary, the brilliant scientist in the black-and-white room, who comes to know the complete physical truth by reading black-and-white science books and watching science lectures on a black-and-white monitor. If physicalism were true, Jackson reasons, then Mary would thereby know everything there is to know about seeing in color: she could deduce that information from her physical knowledge. But, he claims, this is not the case. On the contrary, when Mary leaves the room she learns truths about what it is like to see in color – truths she did not already know.