 Some occurrences are impossible, but may still have explanatory and even causal consequences. It may be impossible to prove a given mathematical conjecture: the conjecture might have a counterexample that nobody has yet noticed. Still, the fact that the conjecture is not proved may have various effects: if you have bet that you will prove it by a certain time you will lose the bet; if your tenure case in the mathematics department turns on whether you managed to prove the conjecture, you will miss out on tenure. Bernstein (2016) gives a theory of omissions of impossible outcomes, and argues that they play an explanatory and causal role.