In his book A Phenomenological Approach to Quantum Mechanics: Cutting the Chain of Correlations Steven French presents an interpretation of Fritz London's and Edmond Bauer's 1939 monograph La théorie de l'observation en mécanique quantique that acknowledges and engages with the phenomenological theorizing underlying their approach to the measurement problem. My aim in the following contribution is twofold. I will first offer some historical and systematic arguments for why it might indeed be worthwhile to explore the link between phenomenology and quantum mechanics. In the second part of the paper, I will then look closer at French's interpretation, especially his understanding of reflection, and express some reservations about a central argument of his.
In his book A Phenomenological Approach to Quantum Mechanics: Cutting the Chain of Correlations Steven French presents an interpretation of Fritz London's and Edmond Bauer's 1939 monograph La théorie de l'observation en mécanique quantique that acknowledges and engages with the phenomenological theorizing underlying their approach to the measurement problem. My aim in the following contribution is twofold. I will first offer some historical and systematic arguments for why it might indeed be worthwhile to explore the link between phenomenology and quantum mechanics. In the second part of the paper, I will then look closer at French's interpretation, especially his understanding of reflection, and express some reservations about a central argument of his.
Abstract The measurement problem remains one of the outstanding issues in the foundations of quantum theory: how do we go from the multiple options encoded in the wave-function to the definite outcome that we observe? One of the most well-known solutions to this problem maintained that it is the observer’s consciousness that somehow causes the wave-function to collapse. Now widely dismissed for introducing an irreducible element of subjectivity into science, both advocates and critics cited a ‘little book’, La Théorie de L’Observation en Mécanique Quantique, by Edmund Bauer and Fritz London (1938; English trans. 1983) as giving the clearest presentation of this solution. However, as well as being an extremely accomplished physicist, London was also trained in the phenomenological tradition that was initiated by the philosopher Edmund Husserl. This casts his work with Bauer in an entirely new and different light, and by assigning a very different and more profound role to consciousness in resolving the measurement problem, yields an understanding of quantum theory that has not hitherto been fully explored. The aim of this book is to initiate just such an exploration. It begins by setting London and Bauer’s ‘little book’ in its historical and philosophical context and then draws out the implications for not only quantum physics but our view of science and the world more generally.
In 1939 London and Bauer published a 'little book' that shaped the debate over the role of consciousness in resolving the measurement problem in quantum mechanics. Mistakenly understood as merely summarising von Neumann's account, both sides in the debate failed to appreciate its phenomenological underpinnings. London not only originally studied phenomenology but continued thinking about and discussing this approach in the years leading up to the publication of his work with Bauer, most notably with Gurwitsch, who likewise had a dual background in phenomenological philosophy and physics. In the book, A Phenomenological Approach to Quantum Mechanics: Cutting the Chain of Correlations (French, 2023), the historical background to London and Bauer's work is set out prior to situating it within the context of Husserl's philosophy as a whole. It is concluded that the London and Bauer phenomenological account offers a potentially fruitful way forward through various dichotomies, such as that between psi-ontic and psi-epistemic accounts and between interpretational and reconstructive approaches more generally, as well as with regard to understanding quantum physics more generally. In this paper London and Bauer's insistence that quantum mechanics should be seen as a theory of knowledge in its own right is emphasized, where this must be taken as phenomenologically grounded. Hopefully this work will be viewed as contributing to a revised phenomenological understanding of modern physics, standing alongside Ryckman's The Reign of Relativity (Ryckman, 2005) and Berghofer and Wiltsche's edited collection Phenomenological Approaches to Physics (Berghofer & Wiltsche, 2020).
In his book, A Phenomenological Approach to Quantum Mechanics: Cutting the Chain of Correlations, Steven French argues that quantum mechanics, understood through the phenomenological lens of London and Bauer, turns physics into a "genuine science", and thus completes the project Edmund Husserl had started in his last major publication, The Crisis of European Sciences. What makes quantum mechanics a genuine science, according to French, is that it is fully grounded in the "lifeworld and transcendental subjectivity", just as Husserl dreamt. While we agree with French that London and Bauer's reading of quantum mechanics is inspired by and thus makes a step towards Husserl's phenomenology, we argue that a more encompassing phenomenological investigation is still needed if we are to avoid another crisis. More specifically, our claim is that French underestimates the "constitutional history" of the kinds of mathematical idealities that underlie quantum mechanics.
The newly revised edition of this well-known book categorizes prevalent views on measurement as described by quantum mechanics, discusses basics agreed to by many who on other issues disagree, and describes some of the problems. Although many paragraphs rest unchanged from the first (1991) edition, results found since 1991 are used to reorganize and sharpen the focus of the book, so that even the old paragraphs are now understood differently and more clearly. One advance in the second edition is a new and more general no-go theorem; another is separation of formal derivations from interpretation. The dozen or so definitions essential to following the book even casually are stated clearly. By this means the authors succeed pretty well in achieving their stated desire to make the book comprehensible to those who do not share their philosophic predispositions. While I differ in philosophy from the authors, attending to their discussion uncovered weaknesses in my own thinking and improved it. The mathematical language of quantum mechanics expresses a system under measurement by states (as rays in a Hilbert space) and a hamiltonian operator, distinct from the apparatus that produces outcomes, which is expressed by a positive operator-valued (POV) measure. In this way quantum language separates state preparation from state measurement. Often the Hilbert space is viewed as a tensor product of subspaces, allowing further conceptual separations. The authors take the stance that quantum mechanics calls for splitting the empirical world into parts, the most essential being (1) objective systems S (to be observed) and (2) apparatus A (preparation and registration devices that produces outcomes (or, as the authors write, definite pointer values) of the observed system). In some interpretations, one or both of an observer and an environment appear as additional parts. What is to be included in the system S versus the apparatus A is not specified by the language, but is open to the theoretician; a probe, for example, can be analysed as either part of the apparatus or as part of the system, as was discussed by von Neumann in work cited by the authors. With what should a theory of measurement be concerned? A broad division of approaches is defined by how one answers the question: should one try to do away with the cut between measuring apparatus and system? The authors phrase this as a choice of REFERENT, a term which in my mind puts them on shaky semantic ground; anyway The Quantum Theory of Measurement is concerned with implications of the `yes'. The book unfolds with the power of a tragedy, in which the logical consequences lead, step-by-step, to the statement and proof of theorem 6.2.1, which, roughly speaking, asserts the non-existence of a solution to the problem of getting definite pointer values from measuring apparatus that exhibits the superposition demanded by its description as a quantum system. Possible responses to this theorem are discussed, among them the many-worlds interpretation and a modification of quantum mechanics that elevates decoherence to a principle. Citations of the literature are thorough, and many points of view are crisply summarized. The book is indispensable to both those who work in the broad direction chosen by the authors and to those who wish to set any other direction in context.
While quantum mechanics has proven successful in its calculations and predictions, a debate persists regarding its understanding. This chapter considers the fundamental concepts of phenomenology and its connection to early quantum mechanics, including the exploration of quantum mechanics by F. London & E. Bauer using phenomenology. Phenomenological investigations of quantum mechanics in recent years have evolved. For instance, the informational interpretation of quantum mechanics, introduced by C. Rovelli in 1996 and advanced by Fuchs and C. M. Caves, offers a new perspective on quantum mechanics and possesses phenomenological tendencies which provide new insights into the problem of quantum measurement. Interestingly, phenomenology has its strong ties to hermeneutics. Therefore, this chapter sheds new light on quantum mechanics via hermeneutical analyses, and bridges the gap between the humanities and the natural sciences. In hermeneutics, interpretation encompasses two key aspects: Erklärung (Explanation) and Auslegung (Explication), where the former establishes clear and objective descriptions, similar to the “shuo ming” (说明) concept in Chinese, and the latter unveils deeper meanings and context, similar to the “chan shi” (阐释) concept in Chinese. The iterative process of explanation and explication plays a crucial role in the development of quantum mechanics. Hermeneutics allows us to view quantum matter with a new perspective, and new features are revealed such as “fusion of horizons” and “history of effects”, where the former is the merging of observer and observed realities in the context of quantum mechanics, while the latter means that the past, present, and future of a quantum system influence its overall reality. For this reason, the photon’s past, in the delayed-choice experiment, becomes an unfinished entity, a superposition waiting to be defined by measurement. This measurement collapses the possibilities and merges the photon’s past and present realities into a single, unified “whole”.
Abstract It has been claimed that Massimi’s recent perspectival approach to science sits in tension with a realist stance. I shall argue that this tension can be defused in the quantum context by recasting Massimi’s perspectivalism within a phenomenological framework. I shall begin by indicating how the different but complementary forms of the former are manifested in the distinction between certain so-called ‘-epistemic’ and ‘-ontic’ understandings of quantum mechanics, namely QBism and Relational Quantum Mechanics, respectively. A brief consideration of Dieks’ perspectivism will then lead to a consideration of the much-maligned and typically dismissed role of the observer in the measurement process. This opens the door to London and Bauer’s presentation of a form of ‘phenomenological quantum perspectivalism’ that brings together Massimi’s two forms and explicitly eschews the ‘naïve’ realism that creates the above tension. I shall conclude with some reflections on how intersubjectivity can still be established within this framework, focusing in particular on how Massimi’s idea of ‘interlacing’ scientific perspectives can be accommodated, using the example of a ‘new cosmopolitanism’ that gave rise to Bose-Einstein statistics.