 A third recent objection is that Russellian monism, despite its aims, fails to adequately integrate consciousness into physical causation. One version of this objection begins with the premise that, on Russellian monism, a single type of physical disposition might have been grounded by a distinct quiddity from the quiddity that actually grounds it (Howell 2015; cf. Robinson 1993). For example, if in the actual world quiddity Q1 grounds negative charge, then there is a metaphysically possible world in which a distinct quiddity Q2 grounds negative charge; the grounding relationship between quiddities and physical dispositions is in this way metaphysically contingent. If so, the argument continues, then quiddities (even if they exist) do not make any distinctive contribution to physical causation. With respect to physical causation, quiddities are “just along for the causal ride” (Howell 2015: 34). On another version of the objection, even if quiddities contribute to physical causation, consciousness does not thereby inherit any physical efficacy, contrary to what Russellian monists claim (Robinson 2018; cf. Chan forthcoming).