"The World(s) According to Quantum Mechanics"

Abstract: Quantum theories are difficult, and insights into the worlds they model are hard-won. The quantum state tells us about values that some physical magnitudes can and cannot take, which suggests a nomological-modal reading. The quantum state is the central dynamical entity of quantum theories, which suggests a descriptive reading. The quantum state is a repository of objective statistical facts about physical systems, which suggests an advisory reading. Frustratingly, these readings sit uncomfortably together, and interpretations of the quantum state typically give one of them up. The goal of this talk is to take seriously all of these insights about the quantum state, set up a framework for their reconciliation, and offer a diagnosis of the source of their apparent incompatibility. That diagnosis is that the incompatibility is forced on us only if we adopt an interpretative strategy that I call relational. A diagnosis is most helpful when it is accompanied by a remedy. I propose one: we should instead adopt an interpretative strategy that I call investigative. I argue that the investigative strategy is the resource we need to answer the question of what the world is like according to quantum mechanics.