 One objection to Russellian monism concerns the combination problem: how do (proto)phenomenal quiddities (or quiddities and structural properties) combine to constitute macrophenomenal properties (Seager 1995; Chalmers 2003)? Suppose someone is having a phenomenally blue experience. If constitutive Russellian monism is true, then the phenomenal blueness of that experience consists wholly in certain quiddities, perhaps structured in a certain way (for the distinction between constitutive and non-constitutive Russellian monism, see Section 4.2). But on many varieties of Russellian monism, quiddities are micro-level features. On the face of it, it seems possible that those (or any) micro-level quiddities could be instantiated without anyone having that (or any) experience—and that seems possible no matter how they are structured. If that is possible, then how could phenomenal blueness consist wholly in (structured) quiddities, as constitutive Russellian monists hold? Essentially the same problem seems to arise for other varieties of constitutive Russellian monism, such as those on which quiddities are construed as cosmophenomenal features (Goff 2009; Pereboom 2011, 114; Chalmers 2013, 2017).