Possibility and Probability

We shall be concerned with real possibility, such as the possibility of a physical event to happen. This kind of possibility is predicated of factual items — things, properties of things, or changes in properties of things. Real possibility is then radically different from conceptual possibility, such as the satisfiability of a formula in a model or the confirmability of a hypothesis by empirical evidence. Conceptual possibility concerns constructs, not things, and it is elucidated without the help of the probability concept — nor, for that matter, is it clarified with the help of modal logics. Not so real possibility: it concerns concrete objects and it is sometimes elucidated in probabilistic terms.