A proposition is necessary if it could not have been false, contingent if it is true (or false) but might have been otherwise, possible if it is true in at least some way things could have gone, and impossible if there is no way things could have gone on which it obtains. Actuality is a separate axis: the actual is what is in fact the case as opposed to merely possible. Possible-worlds semantics (as developed by Saul Kripke, David Lewis, and others) provides an elegant formulation of these relations. Imagine the totality of ways things could coherently have been: each such way is a possible world, and the actual world is just one of them. A proposition is necessary if true in every possible world, possible if true in at least one possible world, impossible if true in no possible world, and contingent if true in at least one possible world and false in others. Necessity is universal quantification over worlds, possibility is existential quantification, and actuality is indexical: it picks out this world, the one we happen to inhabit.
Johannes Climacus, in the “Interlude” of Søren Kierkegaard’s Philosophical Fragments, operates with a version of these distinctions adapted from the work of Friedrich Adolf Trendelenburg. His central claim is that necessity and coming-into-existence are incompatible. Since what is necessary has no unrealized alternatives, there is nothing for a process of becoming to bring about. Whatever comes into being, by contrast, might not have done so or might have come about differently, and its actualization does eliminate alternatives. Thus everything historical is contingent in the strict modal sense even after it has happened: the fact that what’s done can’t be undone is not the same as necessity. The past is unrevisable in the actual world but remains false in countless other possible worlds, and that is enough to keep it contingent. From this Climacus infers that historical claims cannot be objects of demonstrative knowledge in the way logical or mathematical truths are. They must be taken up by belief, an organ specifically suited to apprehending the contingent with all of the uncertainty and ambiguity that entails. Continue reading
