 There has not been much discussion of the knowledge argument from a dualist perspective. This is unsurprising given the small number of contemporary philosophers who defend a dualist position (for a prominent exception see Chalmers (1996); the knowledge argument is discussed on pp. 140–146). There are two possible strategies for a dualist to take who wishes to defend the knowledge argument. The first is merely defensive or ‘destructive’ in that it tries to refute the positive theoretical proposals one by one that have been used by physicalists in their objections against the knowledge argument. The second is more ‘constructive’ in that it aims at developing an alternative positive dualist account of phenomenal concepts, phenomenal properties and their relations such that on that account Mary does learn new and nonphysical facts upon release. Examples (or partial examples) for the first strategy may occasionally be found in the literature (compare Warner 1986, Gertler 1999, Raymont 1995, 1999 and Connell 1994). Examples for the second are hard to find, but Chalmers (1996, 2002) and Nida-Rümelin (2007) exemplify the second strategy. Using his framework of primary and secondary intensions he develops a positive account of what he calls “pure phenomenal concepts” that can be described as incorporating the old and natural intuition that in the case of qualia (phenomenal characters) there is no distinction between appearance and reality, in other words: qualia ‘reveal their nature’ in experience.