 Some of these worries can perhaps be allayed by resorting to the recent work on metaphysical grounding, which presents a much more rigorous analysis of non-causal, metaphysical explanation of this type (see especially the articles in Correia &amp; Schnieder (eds.) 2012a). This is not to take any stand on the relationship between grounding and metaphysical explanation (see §4 of the separate entry on  metaphysical grounding),  but only to note that the discussion surrounding explanatory dependence has progressed, in part, independently of the wider considerations surrounding ontological dependence. So we should perhaps accept that  (EDX)  as it stands does not really constitute a satisfactory definition of a species of existential dependence, conceived as an objective metaphysical relation between entities, because it is insufficiently perspicuous. In any case, the fact that (B-NEC) but not its converse holds some appeal indicates that what we should be trying to frame is a perspicuous definition of a species of ontological dependence that is a relation between x and y stronger than (entailing but not entailed by) “necessarily, x exists only if y exists”. This should moreover be (for reasons discussed earlier) an asymmetrical relation—or, more accurately, an antisymmetric relation, that is, a relation \(\Rrel\) such that if \(x\Rrel y\) and \(y\Rrel x\), then \(x = y\). This is to allow that in principle an object may, in the anticipated sense, depend ontologically upon itself, controversial as this may be (it is nevertheless a position that is of at least historical interest, e.g., because of the potential special case of God depending on herself).