  Combinatorialism takes facts to be literal, structured parts of the  physical world. This suggests that a non-factual state of affairs  — a merely possible fact — must be part of a  merely possible physical world. This idea is at odds with the strong, scientifically-grounded form of actualism that typically motivates  combinatorialism. Two options are available: The combinatorialist can follow the (actualist) abstractionists and define states of affairs  to be philosophical or mathematical constructs consisting only of  actual objects, properties, relations, and facts. For example, the  state of affairs  [R,a1,...,an] can  simply be identified with the ordered n-tuple  ⟨R,a1,...,an⟩. So long as the combinatorialist is willing to adopt the additional  metaphysical or set theoretic machinery, this sort of approach offers a way of introducing non-factual states of affairs that does not  involve any untoward ontological commitments to merely possible  entities. Alternatively, following Armstrong (1989, 46–51;  1997, 172–4), the combinatorialist can refuse to grant  non-factual states of affairs any genuine ontological status and  adopt a form of    modal fictionalism  that nonetheless permits one to speak as if such states of  affairs exist. The exposition to follow will remain largely neutral  between these options. 