Abstract
In this paper, I argue that non-occurrences of events are not qualified as causal relatas from an ontological point of view. It is a matter of fact that we usually use sentences which appear to report non-occurrences of events as causes or effects. But such sentences do not represent the states of the world straightforwardly and hence requires an interpretation. According to the interpretation I endorse, sentences mentioning non-occurrences of events should be interpreted in terms of counterfactuals. This interpretation shows that non-occurrences of events are mentioned on the basis of the concept of possibility. This view is supported by clarifying the ontology of events, confirming the truth condition for counterfactuals, and analyzing cases of double prevention.
