Different kinds of conditionals:Coin tosses and kangaroos in the forest of alternative possibilities

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Our project will provide a novel, unified analysis of conditional sentences ("if A then C") that acknowledges a fine-grained distinction of different kinds of conditionals, employing a formal framework that can represent different kinds of possibilities. The project brings together insights, so far unconnected, from the philosophical study of the formal and metaphysical aspects of varieties of possibilities and from the linguistic study of the interaction of modals and tenses in the compositional structure of conditional sentences. We will build on the philosophical insight that temporal and modal alternative possibilities ("The coin could have landed heads" vs. "Kangaroos could have no tails") require different formal treatments due to their different relation to actuality: tree-like ordered branching structures adequately represent temporal alternatives in our world, while modal alternatives are best represented via distinct possible worlds. We propose to combine these structures for our unified analysis, which will be based on a (modal) forest of (temporally tree-like ordered) alternative possibilities. We will complement these philosophical and formal insights with insights from linguistics, esp. concerning the role that verbal tense plays in determining which kind of possibility is at stake in a conditional under consideration.The project consists of three sub-projects that shall study (1) the dynamics of temporal and epistemic possibilities in conditionals as reflected by the use of tense, (2) conditionals based on modal alternative possibilities, highlighting the role of the past tense in these cases, and (3) the role of causal dependence and independence for conditionals, esp. concerning indeterministic events such as coin-tosses. The main methodological aspects of our project are the cross-fertilization of disciplines and formal modelling. Our aim is to show that a successful integration of current research from linguistics and from philosophy can lead to a unified view of the diverse phenomenon of conditionals.