The principle that <There exists (tenseless) at least one F>, or equivalently, <There ever is an F>, is grounded in <A is an F> for any A is widely held but somewhat controversial. I think it's false in general myself, but there seem to be clear cases. For instance, <There exists at least one turtle> is surely grounded in <Tim is a turtle> and in <Jen is a turtle> and in similar statements for any turtle.
Now suppose that the earliest turtle has descended from two non-turtles, Sally and Mike.[note 1] I think one can't explain why there ever is a turtle without some mention of the descent from Sally and Mike. In particular, that Tim is a turtle does not explain why there ever is a turtle. But that Tim is a turtle grounds that there ever is a turtle. Thus:
- It is possible for a proposition to ground another proposition without explaining it.
A similar point can be made with disjunctions. Suppose you see Sam eat a slug. You ask her why she did that. She says she did it because she chose to. You then ask: "But why did you do it or choose to do it?" And certainly that she chose to do it is not an answer to this question. But that she chose to do it does ground that she did it or chose to do it.
One might of course deny even the seemingly innocent cases of existential and disjunctive grounding that I rely on here. Perhaps when both disjuncts are true or several things exist, the standard disjunctive or existential grounding principles are false?