Although haecceitism and quidditism are independent theses, since neither strictly entails the other, their evidential relationship is an interesting one. Given the parallels between the arguments for and against them, it is unclear whether haecceitists ought to be quidditists and vice versa or if the metaphysical disanalogies between properties and individuals justifying endorsing one but not the other. (On the analogies and disanalogies between haecceitism and quidditism, see Schaffer (2005: 15–16).)