Modal fictionalism

Modal fictionalism is a term used in philosophy, and more specifically in the metaphysics of modality, to describe the position that holds that modality can be analysed in terms of a fiction about possible worlds. The theory comes in two versions: Strong and Timid. Both positions were first exposed by Gideon Rosen starting from 1990. 
Strong fictionalism about possible worlds.
According to strong fictionalism about possible worlds (another name for strong modal fictionalism), the following bi-conditionals are necessary and specify the truth-conditions for certain cases of modal claims:
Recent supporters of this view added further specifications of these bi-conditionals to counter certain objections. In the case of claims of possibility, the revised bi-conditional is thus spelled out: (1.1) it is possible that P iff At this universe, presently, the translation of P into the language of a fiction F holds according to F.
Timid fictionalism about possible worlds.
According to a timid version of fictionalism about possible worlds, our possible worlds can be properly understood as involving reference to a fiction, but the aforementioned bi-conditionals should not be taken as an analysis of certain cases of modality. 
Objections and criticisms.
This objection can be spelled out in at least two ways: artificiality as contingency or artificiality as lack of accessibility.