 The state of affairs of it being the case that \(A\) is grounded by the state of affairs of it being the case that \(B\) iff \(A\) in virtue of it being the case that \(B\), where the relevant notion of “in virtue” is meant to be a metaphysically explanatory one. Grounding is supposed to be a metaphysical analogue of causation: just as causation is what connects the explanans of an explanation with its explanandum in causal explanation, grounding is meant to be what connects the explanans of an explanation with its explanandum in metaphysical explanation. An example of a metaphysical explanation would be an explanation of why a certain type of act is wrong in terms of more fundamental moral facts.