Possible worlds and possible beings: a reflection on ontological commitment

Within the context of debates about God's existence, it is often said that arguing for a negative claim (“God doesn’t exist”) is epistemically more difficult than arguing for a positive one (“God does exist”). But setting epistemic concerns aside, let us consider the ontological commitments of both claims construed as modal possibility claims. It seems ontologically more “loaded” to assert that a certain possible world (with its own domain of individuals and large-scale structure) exists than to assert that a certain being possibly exists. Further unpacking this thought might result in a symmetry breaker between the propositions “Possibly, God exists” and “Possibly, God doesn’t exist” if we take the latter proposition to require quantification over a domain and therefore a commitment to the existence of a certain possible world.