 However, despite these clarifications, it must be conceded that the locution “x exists only because y exists” is hardly very perspicuous, either as to its logical form or as to its exact meaning. Moreover, precisely because we have introduced the conjunction “because” as an explanatory conjunction, it may be felt that it is not well-suited to the ontological role now being devised for it (for one of the many recent attempts to specify the explanatory role of “because”, see deRosset 2013). There are perhaps two sources of worry here: first, that this approach invites a confusion between metaphysics and epistemology; and secondly (but relatedly) that contexts governed by the conjunction “because” are opaque (in the technical sense of the term, in which it implies the non-applicability of Leibniz’s Principle of the Identity of Indiscernibles).