 Many fictionalists are far from explicit about exactly what the content of the fiction of possible worlds is to be. (Often they are also silent on the pressing issue of how one would justify one fiction rather than another: but more on this in section 4). Two explicit proposals were made in 1989 and 1990 about which fiction to use. Gideon Rosen’s 1990 proposed using a slightly modified version of David Lewis’s 1986 theory of possible worlds as the modal fiction. The theory had been proposed by Lewis as the literal truth, but by treating it as a mere fiction Rosen provided a ready-made story about possible worlds, their extent and nature. The other proposal was that of D.M. Armstrong’s 1989. Armstrong proposed a “two-step” fiction, according to which there was a “great fiction”, which asserted the existence of a lot of “little fictions”, each of which completely described a possible world. Armstrong resisted identifying these complete descriptions of ways things could be with the possible worlds, as an abstractionist might, since Armstrong believed that worlds are supposed to be objects like our cosmos, rather than descriptions, properties, or other such abstract objects. Armstrong employed the two stage fiction, on the other hand, because he held that it is true at each world that it is the only world, and if the fiction were of a Lewisian pluriverse each world would (according to the fiction) be such that it was one of many worlds. In this respect, though Armstrong spells out the concern in quite a different manner, it can be seen as an anticipation of the Brock/Rosen objection (see section 3, below). In both the theories of Armstrong and Rosen the “worlds” in the story are thought to be ‘concrete’ cosmoi, like our  own.[3] 