Abstract Phenomenology has also been brought to bear on QM in the context of recent discussions over the approach known as ‘QBism’. This takes the theoretical formalism to be simply a device for predicting an agent’s future experiences, rather than as representing the world. Such a first-person perspective has been widely taken to mesh with the phenomenological stance, as usually understood. However, although advocates of QBism maintain that any slide into solipsism can be resisted, they struggle to accommodate what has been called the ‘kicks from the world’. Here it is argued that in order do so while remaining within a phenomenological framework, the correlationist feature identified by London and Bauer should be incorporated. Interestingly, one of the phenomenologist philosophers who is often cited in this specific context, Merleau-Ponty, took classes with Gurwitsch and drew on London and Bauer’s ‘little book’ in his own analysis of quantum physics.
Abstract Phenomenology has also been brought to bear on QM in the context of recent discussions over the approach known as ‘QBism’. This takes the theoretical formalism to be simply a device for predicting an agent’s future experiences, rather than as representing the world. Such a first-person perspective has been widely taken to mesh with the phenomenological stance, as usually understood. However, although advocates of QBism maintain that any slide into solipsism can be resisted, they struggle to accommodate what has been called the ‘kicks from the world’. Here it is argued that in order do so while remaining within a phenomenological framework, the correlationist feature identified by London and Bauer should be incorporated. Interestingly, one of the phenomenologist philosophers who is often cited in this specific context, Merleau-Ponty, took classes with Gurwitsch and drew on London and Bauer’s ‘little book’ in his own analysis of quantum physics.
Two decades after its creation, the interpretation of quantum mechanics called QBism is entering a new phase. Since it shares a personalist, subjective worldview with phenomenology, the philosophical study of human experience, there is a growing interest in the relationship between the two subjects. I call attention to the little-known philosopher Samuel Todes, whose phenomenology focused on the essential role of the human body in our understanding of the world. After reviewing this radical proposal, and illustrating it with some examples, I recommend it as an interesting mediator between the communities of physicists and phenomenologists. In addition, I argue that it may prove useful for promoting the public understanding of QBism.
This is the first volume that focuses specifically on phenomenological approaches to quantum mechanics. It is also the first volume focusing on the philosophical implications of QBism. This coincidence is not accidental. Phenomenology's rich potential for our understanding of quantum mechanics has long been overlooked by analytic philosophers and phenomenologists alike. The experience-first approach of phenomenology, its descriptive methodology, and Husserl's critique of mathematization do not sit well with “mainstream” analytic philosophy of physics. But as this volume will demonstrate, it sits nicely with the basic tenets of QBism. Conversely, QBism constitutes the most consistent and best-developed interpretation of quantum mechanics that fully embraces the Bohrian idea that a proper understanding of science must be based on the concept of experience. However, since its inception in the early 2000s, QBism has struggled to connect with the philosophical community. Not only are the underlying intuitions shaping and dominating contemporary philosophy of quantum mechanics—namely, that a scientific theory must be purged of all subjective and operational notions such as “experience” or “measurement” and that, consequently, a successful approach to quantum mechanics must be formulated as a “quantum theory without observers”—at odds with QBism. It seems that sometimes the incommensurability already starts at the level of the basic conceptual framework which, in the case of mainstream analytic philosophy, is not very well suited to express some of QBism's main tenets. Considering this situation, the main hypothesis of this volume is that phenomenology and QBism are natural bedfellows, and that both can profit from mutual exchange. In order to make this exchange as profitable as possible, the aim of this introductory chapter is to identify, clarify, and motivate some of the cornerstones of phenomenological approaches to quantum mechanics, to shed light on the main ideas and virtues of QBism, and to discuss points of contact and points of possible conflict between these two projects.
Abstract Both the ‘Many Worlds’ interpretation and Relational Quantum Mechanics are typically presented as interpretations of quantum theory, whereas QBism is understood as a reconstruction of it. The latter has been suggested as the appropriate approach for phenomenologists to adopt, particularly since this account adopts a first-person perspective. However, in Chapter 10 it is argued that such a dramatic move is not necessary as London and Bauer have already laid down the groundwork for an appropriately phenomenological understanding of the theory. This can then be supplemented with the relationist features emphasized by ‘Many Worlds’ and RQM. Husserl himself insisted that phenomenology does not require any such reshaping of scientific practice itself, theoretical or otherwise; rather it and its foundations need to be understood from the perspective afforded by the epoché. It is precisely this understanding that London and Bauer’s ‘little book’ presents, with the theory taken as not just a piece of physics but a theory of knowledge in itself. The chapter, and book, concludes with the suggestion that as a result, London and Bauer’s account sits somewhere between an interpretation and a reconstruction of the theory and by virtue of that, represents a novel advance in considerations of how we should conceive of our relationship to the world.
A discrepancy between the instrumentalist and realist inclinations of QBism, or between its experiential and interactional concepts of measurement, has been repeatedly noticed. Here, we show that this discrepancy can be resolved by adopting a phenomenological approach throughout. In other terms, the difficulty can be overcome by unambiguously choosing the first-person standpoint as a radical origin of knowledge, and by ascending from the situated lived experience of a knowing and acting subject, to the structure and use of the quantum formalism. To reconstruct some crucial features of the objectivity promised by science, and to accommodate the soundest aspect of the realist intuitions of QBist authors, a phenomenological reinterpretation of what is commonly called “the world” is proposed. This reinterpretation is based on Bruce Bégout's “Eco-Phenomenology”, that replaces the concept of a somehow extrinsic relation between subject and world, with the immersive experience of a subject partaking of the world.
The history of QBism is interestingly complex, leading to misunderstandings and misapprehensions as to its core features. Fuchs has usefully situated those features within the framework constituted by forms of ‘participatory realism’ according to which measurement devices should be considered to be extensions of agents. Examining that claim, Pienaar has articulated the conditions that such devices must meet to be so considered. However, there has yet been little similar consideration of the conditions that agents must meet in this regard. Here I shall examine the proposal that adopting a phenomenological stance may fill the gap in the QBists’ picture and I shall present an alternative ‘correlational’ account.
This chapter expresses what a breath of fresh air it has been since a few phenomenological philosophers have started to engage with QBism. In service of the newfound discussion, the aim of this exposition is to lay out the structure of QBism as clearly as possible for that audience. In the process, we arrive at eight tenets for QBism: (1) A quantum state is an agent's personal judgment. (2) A quantum measurement is an agent's action upon its external world. (3) Quantum measurement outcomes are personal to the agent performing the action. (4) The quantum formalism is normative rather than descriptive. (5) Unitary evolution too expresses an agent's degrees of belief. (6) Even probability-one assignments are judgments without ontic content. (7) Subjective certainty about what an outcome will be does not negate that unperformed measurements have no outcomes. And, (8) quantum theory is a single-user theory for each of us. We then analyze the Wigner's friend thought experiment in light of the eight tenets and indicate that a still more extended analysis is potentially QBism's surest path to uncovering an ontology to go with quantum theory's normative structure. We conclude with a small discussion of how the philosophy of Maurice Merleau-Ponty may be relevant to this quest.