Some things are true; some are false. Some are true, but might have been false. Some are true but could not have been false. Some are false, but might have been true. Some are false but could not have been true. Thus, there are at least these different modes of truth and falsity: necessity and possibility. A truth bearer—a proposition, a statement, or an interpreted sentence—is necessarily true if and only if (iff) it is not possible that it be false; it is possibly true iff it is not necessary that it be false. A contingency is what is possibly true as well as possibly false. The study of the ways in which truth and falsity interact with necessity and possibility is the subject of modal logics.

If there are modal distinctions to be made about truth bearers...