  The specter of possibilism first arises with regard to non-actual possible worlds, which would seem by definition to be prime examples of mere possibilia. However, we have just seen that the abstractionist can avoid this apparent commitment to possibilism by defining possible worlds to be SOAs of a certain sort. So defined, non-actual worlds, i.e., worlds that fail to obtain, can still actually exist. Hence, the commitment of basic possible world semantics to non-actual worlds does not in itself threaten the actualist's ontological scruples. 