Understanding Quantum Theory: An Operational Reconstructive Approach

One hundred years after the creation of quantum theory, there is no consensus on the kind of reality that is described by the theory. In this paper, I attribute the lack of progress to the prevailing interpretative methodology, which invariably takes the quantum formalism as the starting point for philosophical reflection and analysis. I argue that this methodology is particularly inappropriate for quantum theory. In particular, it invariably marginalizes much of the theory's content, both that implicit in modelling heuristics and experimental practices, and that encapsulated in the mathematical structures of its formalism. In addition, the prevailing methodology offers little protection against undue influence by metaphysically-laden language which invariably accompanies the formalism. Here, I summarize an alternative methodology whose goal is to ensure that an interpretational project take into account all forms of theoretic content. The methodology harnesses the recent results of the quantum reconstruction program. These results distil the mathematical content of the quantum formalism into physical principles and assumptions, which are more readily philosophically digestible that the formalism itself, and bracket much of its metaphysically-laden language. I also outline the main features of quantum reconstruction with a view to highlighting its significance for philosophic interpretation, and describe the value of adopting an operational stance during both reconstruction and interpretation. As a case study of reconstruction-based interpretation, I describe the reconstruction of the identical particle formalism, and its step-by-step interpretation, highlighting both the key questions that drive the interpretation forwards and the techniques and stances that are employed in each step. The interpretation yields a novel metaphysical profile for systems of identical particles as potential parts of a whole, which can be traced step-by-step to elementary experimental data and the reconstruction's physical postulates and assumptions. Finally, I describe some of the pitfalls that one faces in any attempt to directly interpret the identical particle formalism.