Quantum Metaphysical Indeterminacy

On a wide variety of presently live interpretations, quantum mechanics violates the classical supposition of ‘value definiteness’, according to which the properties (‘observables’) of a given particle or system have precise values at all times. Here we consider whether two recent approaches to metaphysical indeterminacy— a metaphysical supervaluationist account, on the one hand, and a determinable- based account, on the other—can provide an intelligible basis for quantum metaphysical indeterminacy (QMI), understood as involving quantum value indefiniteness. After identifying three sources of such QMI, we show that previous arguments (Darby in Australas J Philos 88:227–245, 2010; Skow in Philos Q 60:851–858, 2010) according to which supervaluationism cannot accommodate QMI are unsuccessful; we then provide more comprehensive arguments for this conclusion, which moreover establish that the problems for supervaluationism extend far beyond the orthodox interpretation. We go on to argue that a determinable- based approach can accommodate the full range of sources of QMI.