Title: Branching Time and the Semantics of Future Contingents
In the series of talks, I weave together two threads present in the philosophy of Branching Time—semantics and metaphysics. I relate the semantic theories introduced in the setting to their underlying, metaphysical considerations. In the model of Branching Time, alternative paths of evolution of a system are represented by a treelike structure. I first investigate the metaphysical significance of the model. I pay special attention to the assumption of modal neutrality which has been widely accepted in the field. According to modal neutrality, all elements of the branching structure are equally real. In particular, no part of the structure can be absolutely distinguished as actual. I call the brand of theories that accept modal neutrality Branching Realism. I investigate how the assumption of modal neutrality influences the semantic treatment of future contingents, i.e., statements concerning possible, but not necessary, future events. I argue that realistic set-up is particularly hostile to futurism (i.e., the thesis that some future contingents are true). Against the background of Ockhamist semantics, I outline a number of alternatives available to Branching Realists; specifically: modalism, extremism, three-valued semantics, supervaluationism, and relativism (including assessment relativism, history relativism, and local relativism). Then, I investigate the semantic theories that combine branching with futurism. The Thin Red Line theory, as I understand it, took upon itself the unpromising task of introducing futurism into the Genuinely Realistic worldview. It generates a tension that can be, and has been, exploited to attack this theory on metaphysical and semantic grounds. I conclude that the only way to defend futurism in the context of branching is by rejecting modal neutrality. I call this view Branching Actualism. In Branching Actualism, we can conditionalize the truth value of sentences about the future on what will actually happen in the future. Then, bivalence of future contingents becomes a rather non-controversial idea. I argue that Branching Actualism avoids the the objections that threatened the Thin Red Line theory.