Quine's criterion is silent on the ontological commitments of theories couched within intensional languages—languages with intensional operators such as ‘it is possible that’ or ‘it will be that’ or ‘it is believed that’. If it were directly applied to such languages, it would run the risk of undergenerating ontological commitments: perhaps there are commitments hidden by the intensional operators, as would be the case if they are disguised quantifiers.  Quine's extended criterion involving paraphrase can be applied; but now there is a danger of overgenerating. For paraphrases of theories couched within an intensional language into first-order predicate logic will almost inevitably have to treat the intensional operators as disguised quantifiers, and it may be that any adequate domain for those quantifiers will require controversial entities that do not correctly represent the ontological commitments of the original intensional theory. For example, if modal theories are “translated” into first-order logic in the standard way, where ‘possibly’ means ‘at some possible world’ and ‘necessarily’ means ‘at all possible worlds’, they will be ontologically committed to possible worlds according to the extended quantifier criterion. But this seems to just beg the question against the modalist who does not think she is so committed. (For problems with the extended criterion, see §4.2.)