 In response to the first version of that objection, on which quiddities lack physical efficacy, some reject the assumption that any such conclusion follows from the premise that a single type of physical disposition might have been grounded by a distinct quiddity from the quiddity that actually grounds it (Hawthorne 2002, Alter and Coleman forthcoming). Causal relations, it is argued, do not in generally hold with metaphysical necessity. So, why must the relationship between quiddities and dispositions hold with such necessity, if quiddities are to be physically efficacious? Another response is to reject the premise that on Russellian monism that relationship is metaphysically contingent (Chalmers 2013 [2015: 264–65]; Mørch 2014; Gundersen 2015; Kadić 2017; Alter and Coleman forthcoming). In response to the second version of the objection, on which consciousness does not inherit any physical efficacy from that of quiddities (even if quiddities partly or wholly constitute consciousness), one might argue that this charge is just an instance of a general worry concerning micro-to-macro causal exclusion, which does not concern consciousness or Russellian monism specifically. (See the entry  mental causation;  Goff 2017: 153–58)