One important argument against haecceitism turns on issues about the grounding of identity facts—i.e., facts about the identity of individuals. Set out in Forbes (1985: 128), this argument holds haecceitism to require what we can call bare identity facts, where such facts concern the identity of individuals but are not grounded in the qualitative features of the world. Since these identity facts can vary without any difference in qualitative character, they are alleged to resist metaphysical explanation. On this front, Forbes remarks as follows: