Blurring: Structural Realism and the Wigner Puzzle

Jonathon Sendall

This paper argues that several canonical puzzles in quantum mechanics, including spin measurement, the double slit, entanglement correlations, and Wigner's friend, share a common origin in a semantic error and the illicit promotion of interaction conditional outcomes to intrinsic properties. I introduce four principles that license only configuration relative predication, grounding outcomes in physical measurement geometry while preserving objectivity. Applying these principles uniformly dissolves each puzzle without new physics or ad hoc interpretive machinery. Bell's theorem and the Kochen-Specker theorem are reframed not as dynamical mysteries but as constraints on permissible explanatory structure, evidence that intrinsic-outcome semantics is incompatible with empirical reality. The result is a relational objectivity that avoids both naive property realism and observer subjectivism.

Steven French

Bryan Wilson Roberts

We present a precise form of structural realism, called group structural realism, which identifies ‘structure’ in quantum theory with symmetry groups. However, working out the details of this view actually illuminates a major problem for structural realism; namely, a structure can itself have structure. This article argues that, once a precise characterization of structure is given, the ‘metaphysical hierarchy’ on which group structural realism rests is overly extravagant and ultimately unmotivated. 1 Introduction 2 What is (Group) Structural Realism? 2.1 The basic picture 2.2 Wigner’s legacy 2.3 Accounting for theory change 3 The ‘Higher Structures’ Problem 3.1 The structure of a structure 3.2 Higher structures and theory change 3.3 Any way out for the groupies? 3.3.1 Chopping down the tower 3.3.2 Playing favorites 3.3.3 Adopting the whole shebang 4 Conclusion Appendix

Časlav Brukner

Ruth E. Kastner

In this chapter, the metaphysics of quantum possibilities, as a form of res potentia , is discussed. The transactional picture, together with quantum possibility, can be understood in terms of Kant’s contrast between phenomena and noumena, with quantum possibility constituting an element of the noumenal realm. This formulation sheds light on the connection between the two realms. It also provides a “middle way” between realism and antirealism and resolves puzzles surrounding the notion of causation. Concerns about structural realism are also addressed.

Aleksandr V. Belinsky