 Jonathan Schaffer has relied on the notion of ground to revive an Aristotelian, structured metaphysics, i.e., a metaphysics which is ordered by priority relations (Schaffer 2009), and to defend Priority Monism (see the entry on  monism).  In response, Michael Della Rocca (2014) has argued that strict adherence to the PSR—and to Ockham’s Razor (see the entry on  simplicity)—undermines  Schaffer’s structured metaphysics (and Priority Monism), since insofar as all the features of the grounded are already present in the ground, the existence of the grounded is just redundant. (See also the entry on  metaphysical grounding).