Branching in the landscape of possibilities

Abstract

The metaphor of a branching tree of future possibilities has a number of important philosophical and logical uses. In this paper we trace this metaphor through some of its uses and argue that the metaphor works the same way in physics as in philosophy. We then give an overview of formal systems for branching possibilities, viz., branching time and (briefly) branching space-times. In a next step we describe a number of different notions of possibility, thereby sketching a landscape of possibilities. In the final section of the paper we look at the place of branching-based possibilities in that larger landscape of possibilities. Our main message is that far from being an outlandish metaphysical extravagancy, branching-based possibilities are epistemically as well as metaphysically basic.Keywords Branching time · Branching space-times · Modality · Possibility · ExperimentThe metaphor of branching is useful for describing a certain type of modality: an open future can be pictured as a branching tree of concrete possibilities. In this paper we will look at the place of branching-based possibilities in the larger landscape of possibilities. The main message is that far from being an outlandish metaphysical extravagancy, branching-based possibilities are absolutely basic.The paper is structured as follows: In Sect. 1 we trace the branching metaphor through some of its uses and argue that the uses in philosophy and in the sciences are of a piece. In Sect. 2 we briefly describe two formal frameworks for branching-based possibilities, branching time and branching space-times. Section 3 centers on the notion of a scientific experiment to motivate different types of possibilities, thereby giving

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