A specialization of conjectural context. Each instance MT of Cyc counterfactual context is a microtheory for which the following property holds: there is at least one assertion ASSERT which holds in MT (so that (Ist MT ASSERT) is true), but which is widely believed to be false. Although microtheories with this property would appear to have limited utility, they can be useful in reasoning about the content of fictional works or the content of certain belief systems. An important specialization of Cyc counterfactual context is fictional context (q.v.).