"Possibilism" is the view that among the things that there are, or which have being»are included individual objects which do not exist, although they conceivably could have existed, and would have existed if certain possible-but-unrealized states of affairs had obtained. In this paper I try to develop a plausible ontological context from which the possibilist thesis could be deduced. Among the assumptions that are required for the argument is the idea that a state of affairs is a complex entity individuated (...) by its constituents and their arrangement in that state of affairs. This is contrasted with Chisholm's strategy for individuating states of affairs. If one also assumes that possible states of affairs have their status as possibilities as a matter of logical necessity, then it is shown how a possibilist could argue that non-existent objects would have being as constituents of possible-but- non-obtaining states of affairs. In particular, possibilism could be seen as the view that the being of non-existent objects is required as an ontological ground of the possiblity of there having existed objects other than those things that do actually exist. (shrink)