Morris Weitz famously claims that art is an indefinable-because-open concept. As a corollary to Dickie's assertion (via M. Mandelbaum) that Weitz neglects the "unexibited" common properties of art objects, I want to suggest that Weitz conflates indefinability and openness, overlooking in the process the possibility of a definable-yet-open conception of art. (I find Dickie's two-part definition unsatisfactory because too inclusivist. There will be more than two necessary conditions.)
Furthermore, Weitz's global dismissal of definitions assumes that any satisfactory definition of art must be an "intensional" one (a specification of the necessary and jointly sufficient conditions required of each member of the set under consideration). But Weitz's preferred extensional (in this case, ostensive) definition of art is still, obviously enough, a definition.
Even so, I remain hopeful that we might construct a satisfactory -- however inclusive and broad -- intensional definition of art. I will offer my own (closed, intensional, classical) definition of art in a later post.