 One of the most lively areas of philosophy of mind concerns the issue of which if any of these responses to the knowledge argument will be successful. (See the papers in Ludlow, Nagasawa, and Stoljar 2004. See also  Qualia: The Knowledge Argument)  The ability response raises questions about whether know-how is genuinely non-propositional (cf. Lycan 1996, Loar 1997 and Stanley and Williamson 2001), and about whether it gets the facts right to begin with (Braddon Mitchell and Jackson 1996). As against a posteriori physicalism, it has been argued both that it rests on a mistaken approach to the necessary a posteriori (Chalmers 1996, 1999, Jackson 1998), and that the promise of the idea is chimerical anyway (cf. Stoljar 2000). The third response raises questions about the distinction between the object and the theory conception of the physical and associated issues about dispositional and categorical properties, and also about the relation between physicalism on the one hand, and a related view, sometimes called Russellian monism. See  Russellian monism,  as well as Chalmers 1996, Lockwood 1992, Stoljar 2000, 2001, Montero 2010, 2015) 