The co-occurrence test for non-monotonic inference

According to the co-occurrence test, q is (non-monotonically) inferrible from p if and only if q holds in all the reasonably plausible belief change outcomes in which p holds. A formal model is introduced that contains representations of both the co-occurrence test (for non-monotonic inference) and the Ramsey test (for conditionals). In this model, (non-nested) conditionals and non-monotonic inference satisfy the same logical principles. However, in spite of this similarity the two notions do not coincide. They should be carefully distinguished from each other.