 The first proposal, to subsume physical objects under kinds, entails that the Mona Lisa isn’t a physical object but a kind of painting. One difficulty with this is that as a kind, the Mona Lisa wouldn’t have any perceptual properties, which is both strange and in violation of Beardsley’s critical postulates. A second difficulty is that it’s a necessary truth—or at least many philosophers think it’s a necessary truth—that there’s only one Mona Lisa, yet the view in question entails that there could be many Mona Lisas, many instances of the kind.