Unlike extensional criteria, the modal entailment criterion has no problem with (contingently) false existentials. The sentence ‘∃x Unicorn(x)’ is ontologically committed to unicorns because, at every world at which it is true, the domain of that world contains at least one unicorn. In saying this, the meta-ontologist may or may not herself be ontologically committed to unicorns depending on how the meta-ontologist construes talk of possible worlds and possible individuals. A modal realist—someone who takes possibilia to be concrete—will be so committed. But an ersatz modal realist—someone who takes possibilia to be in some sense abstract—will interpret “the domain of that world contains at least one unicorn” in a way that does not commit the meta-ontologist to unicorns; abstract worlds can represent unicorns as existing whether or not unicorns exist.[12]