 Of course, there may be very general reasons to reject grounding talk altogether (see the discussion in the entry Metaphysical Grounding). In the present context, one criticism deserves close attention. Wilson (2014) maintains that reference to a primitive metaphysical relation in articulations of various dependence claims does not constitute philosophical progress. Many of the various detailed explications of different types of dependence, including mereological dependence, supervenience, and the relation between determinables and determinates, promise illumination, whereas grounding talk is ultimately obscure, mainly for two reasons. First, ‘ground’ is supposed to be primitive. Second, its structural features of a partial order – ground is irreflexive, asymmetric and transitive – are too permissive and too narrow at the same time, to single out a particular relation of metaphysical dependence, says Wilson. It is too permissive because temporal order and causation may have the same structural features (Wilson 2014, 569). It may be too narrow because, for instance, mixed cases of dependence may violate transitivity (Schaffer 2012, Wilson 2014). So, even if there is prima facie evidence that reduction and ground are closely linked, it is an open question whether shifting attention from theories of reduction to the metaphysics of ground will prove fruitful. 