 A final issue concerning both the New Knowledge/Old Facts View and the knowledge argument itself is whether there are any phenomenal concepts. Derek Ball (2009) and Michael Tye (2009) argue that there are no such concepts, at least as defined above: in particular, both deny claim (4) outlined in Section 4.6, that a subject can possess phenomenal concepts only if it has or has had experiences of the relevant kind. Ball and Tye appeal to work on social externalism regarding the content of our concepts to argue that even prior to her release, Mary possesses the same concepts which she uses to think about her experiences after her release. Specifically, she possesses such concepts ‘deferentially’, in virtue of interacting with her linguistic community; a crucial part of social externalism about content is that one can possess concepts deferentially even though one is largely ignorant of the nature of what satisfies these concepts (Ball 2009, 947–954; Tye 2009,  63–70).[6]  This result threatens to undermine the New Knowledge / Old Facts View, but Ball suggests it also undermines the knowledge argument itself, since the knowledge argument itself depends on there being phenomenal concepts (2009, 940–943).