Experience, Phenomenology, and Quantum Mechanics

Philipp Berghofer

Department of Philosophy, University of Graz, Austria

Experiences are our points of contact with the world. They constitute the ineluctable starting point and epistemological foundation of any scientific investigation. More precisely, in my view, they are a source of immediate justification and our ultimate justifiers. But what makes experiences special, what gives them their justificatory force? In The Justificatory Force of Experiences (2022) I have introduced what I call the phenomenological conception of experiential justification (PCEJ). This is the claim that justification-conferring experiences gain their justificatory force by virtue of their distinctive phenomenology. By phenomenology I understand the experience’s phenomenal character, the what-it-is-like character to undergo a specific (type of) experience. Perceptual experiences, for instance, have a distinctive presentive phenomenology that distinguishes them in their epistemic role from other mental states. PCEJ has several interesting implications. For instance, it closely connects epistemology and philosophy of mind. This is because if PCEJ is true, then the descriptive analysis of different types of mental states and experiences becomes an indispensable component of epistemology. In this picture, epistemology and consciousness are intrinsically related such that every piece of justification can be traced back to experience and an experience’s justificatory force is grounded in its phenomenology. Accordingly, PCEJ is in strong opposition to mainstream epistemology that treats conscious experience and epistemic justification as separate topics. This is because contemporary analytic epistemology is dominated by externalist accounts according to which justification/knowledge is grounded in external factors such as truth or reliability instead of internal factors such as an experience’s phenomenology. In short, I champion a phenomenological experience-first epistemology that attributes a central role to conscious experience. This epistemological system is introduced, motivated, and defended in Part I of The Justificatory Force of Experiences. In Chapter 15 I discuss this in the context of modern physics, aiming at specifying phenomenological approaches to physics. There are at least three reasons why it is interesting and important to engage phenomenological approaches to epistemology with phenomenological approaches to physics. (“Phenomenological” broadly understood as being in the spirit of Edmund Husserl’s phenomenology.)

1. There is the threat that modern physics renders my experience-first epistemology obsolete. This is because prominent voices in philosophy of science, most notably Wilfrid Sellars, have claimed that modern physics suggests that the world as we experience it is mere illusion. Similarly, prominent voices in philosophy of physics, most notably David Albert, have claimed that quantum mechanics suggests that (three-dimensional) physical space is mere illusion. Accordingly, one could argue that even if everything I say about experiential justification is true, this is obsolete because the prima facie justification delivered by experiences is defeated by modern physics.

2. I assume it is plausible and in agreement with common sense to posit that there is an intimate link between an experience’s justificatory force and its phenomenology. If you are walking down an avenue and you are perceptually presented with an avenue flanked by cherry trees, it is natural to assume you are justified in believing that there are trees. If, instead, your experience presents you with an avenue flanked by cars, it is natural to assume you are justified in believing that there are cars. Undergoing a perceptual experience of an avenue flanked by cars but believing that there are trees (and no cars) would be strange and unjustified. So why is it that externalist accounts, opposing my PCEJ, are so prominent in contemporary epistemology? One reason is that externalism seems to fit well with what one might call the naturalistic turn that occurred in the second half of the 20th century. This was a turn toward the natural sciences, imposing on philosophy the still prominent view that philosophy should strive to be methodologically similar to the natural sciences. In this context, the natural sciences are typically understood as adopting a third-person perspective that successfully abstracts away from the subject and her personal experiences. Accordingly, one possible objection against my internalist experience-first epistemology is that externalism seems to resonate better with the practice of science. However, if it turns out that science, at a fundamental level, must embrace the first-person perspective, this motivation for externalism implodes. In fact, if a “phenomenological” interpretation of quantum mechanics such as QBism or the London-Bauer- French interpretation – discussed in Chapter 15 and sketched below – were true, this would turn the tables.

3. In light of the above, one might hope to specify the relationship between epistemology and science as follows: Epistemology, at its core, has the objective of clarifying the epistemic role of experiences. This amounts to an a priori analysis of how experience relates to the justification of beliefs. The most basic aim of science, then, is to develop the formalism that allows the experiencing subject to answer the following question: Given my actual experiences, what should I believe (to experience next)? This formalism, plausibly, is the formalism of quantum mechanics. Thus, by engaging phenomenological approaches to epistemology with phenomenological approaches to physics, one might hope to introduce a unified account of experiential and scientific justification. 2 But what do I mean by phenomenological approaches to physics, particularly quantum mechanics? Recently, Harald Wiltsche and I have identified and specified three cornerstones/guidelines (in our forthcoming volume on phenomenology and QBism).

4. Life-world first! (against wave function realism): The justification for any scientific theory can be traced back to epistemically foundational experiences. Thus, if the results of science are interpreted as implying that our experiences are illusory, science itself becomes illusory. To put it differently, if the sciences reveal the illusory character of our experiences, they cast doubt on their own epistemic foundation. Accordingly, phenomenologists should be skeptical about interpretations of scientific theories that imply that science tells us that the world of our everyday experiences is mere illusion. Furthermore, one prominent phenomenological guideline (at least since Husserl’s Crisis of the European Sciences) is that we should be careful in our ambitions of objectifying/reifying the mathematical symbols of our scientific theories. The danger is that we confuse what is merely a method to represent reality with reality itself.

5. Physics first! (against modificatory interpretations): One of Husserl’s best-known slogans is “back to the things themselves.” This encapsulates the phenomenological doctrine that we must respect the phenomena, be mindful about how things are given/presented to us, and should be cautious in our ambitions to “explain away” the phenomena when they don’t fit our theories. In the context of interpreting quantum mechanics this is relevant because modificatory interpretations such as Bohmian mechanics actually change (and complicate) the formalism of quantum mechanics in order to make sense of it. While Bohmian mechanics proves that the formalism of quantum mechanics can be modified such that deterministic equations account for seemingly random phenomena, this move can be criticized for altering the formalism of the most successful theory in the history of science for the benefit of satisfying an outdated deterministic particle ontology that is a perfect fit for classical mechanics but not for quantum mechanics. (Of course, the full story is more complicated.) Phenomenological considerations suggest the following guiding principle: If we can make sense of quantum mechanics either by modifying the formalism such that phenomena like quantum indeterminacy/randomness are explained away and an objectivist understanding of science is preserved or, on the other hand, by taking the formalism and the phenomena seriously and accepting a non-objectivist understanding of science, other things being equal, we should opt for the latter option.

6. Experience first! (against objectivist interpretations): It has become a commonplace in phenomenology that a purely objective third-person perspective is unreachable. This is often understood as the claim that although there inescapably always remains some subjective residuum, delivering a purely third-person perspective on the world should continue to be the (unreachable) goal of science. However, some phenomenologists, perhaps most notably Merleau-Ponty, have argued that the sciences should embrace the first-person perspective and make the scientist a part of science. Drawing on ideas of the physicists Fritz London and Paulette Destouches-Février, Merleau-Ponty argued that quantum mechanics exemplifies such phenomenological teachings. In my view, there currently exist two interpretations of quantum mechanics that come closest to exemplifying the ideas above. These are QBism and the interpretation offered by Fritz London & Edmond Bauer in 1939 that was rediscovered and systematized in the context of modern debates by Steven French. I call the latter approach the London-Bauer-French interpretation (LBF). QBism and LBF are both discussed in Chapter 15 of The Justificatory Force of Experiences and the state of the art is summarized in my companion essay to this précis. QBism explicitly embraces the idea that the concept of “experience” is fundamental to understanding science in general and quantum mechanics in particular. For QBists, the quantum state (i.e. the wave function) does not represent objective reality but instead represents an agent’s subjective degrees of beliefs about her future experiences. Central to QBism is the notion of the agent. Quantum mechanics, according to QBism, is not about objectively describing external reality but is a tool for an agent to improve their decision-making. An “agent” is defined by QBists as an entity that can freely act on the world and to whom the consequences of their actions matter. This is how consciousness enters the scene. An agent is not just any physical entity. Electrons and stones do not qualify as agents. For a subject to freely take actions and care about the consequences of their actions, (self-)consciousness is required. The London-Bauer-French interpretation (LBF) emphasizes the role of consciousness even more straightforwardly than QBism. Here the main idea is that entanglement must be applied to consciousness and that conscious subjects have the unique feature that by the faculty of introspection they can separate themselves from the wave function. Historically, the approach of London and Bauer has been misunderstood as the view that nonphysical consciousness somehow causes the wave function to collapse. However, as has been shown convincingly by Steven French, this view may have been advocated by Wigner and perhaps von Neumann but it is not the view expressed by London and Bauer. Instead, according to London and Bauer, the quantum formalism includes the different states of the observer, subject and object 4 being interrelated, but it is via the faculty of introspection that the observer can keep track of her states which leads to a mutual separation of subject and object. Contemporary philosophy of quantum mechanics is dominated by so-called “quantum theories without observers” that seek to avoid any irreducibly subjective/operational concepts or perspectival moments. Phenomenological approaches constitute an alternative that embraces the operational flavor of quantum mechanics. One of my main research interests is whether we can systematically engage a phenomenological experience-first epistemology with phenomenological approaches to physics. QBism and LBF suggest themselves as plausible candidates. I hope that here I have succeeded in strengthening the interest in these approaches.

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