Popper’s Propensity Interpretation of Quantum Physics as a form of Modal Metaphysics

Abstract

With the emergence of quantum physics in the 1920s, the major philosophical question was, do the unobservables in quantum system have ontological status or are mere instruments for scientific prediction? The Copenhagen interpretation developed an instrumentalist thesis, contending that the unobservables are tools for making predictions concerning the observables. Thus, we cannot have knowledge of the quantum particles. However, Popper attempts a realist and an objective interpretation. As such, he criticizes the Copenhagen interpretation, developing the propensity view, which accords ontological status to subatomic particles. The main thrust of our argument in this paper is that by replacing probability possibilities with propensities, Popper positions himself as a proponent of the metaphysics of modality. It is then our objective to establish the parallelism between Popper’s Propensity Interpretation and Modal Metaphysics. To establish this contention we proceeded analytically: firstly by situating the seismic shift from macro to quantum physics, secondly by examining Popper’s critique of the Copenhagen Interpretation and thirdly by attempting a demonstration of the correlation between Popper’s propensity interpretation and modal metaphysics. The merit of this paper resides in its elucidation of the importance of metaphysics in science. It is a double challenge at the same time for antimetaphysical philosophy of science and for antiscientific metaphysics, to rethink the relationship between Metaphysics and science and invest in finding how both disciplines nurture each other. Finally, it is hoped that policy makers in Philosphy and science uses our findings to revamp the conceptualisation and practice of interdisciplinarity.