The Human Element: Riezler’s Critique and Rovelli’s Defense of Quantum Physics

I. Abstract

Imagine a universe where nothing has a definite state until you look at it. The tension between scientific abstraction and the real human experience has elevated with the emergence of quantum physics, a field that reveals a nature of reality that subverts the “common sense” world we perceive. Unlike human experience, grounded in concrete, sequential events, quantum physics suggests a probabilistic, interconnected universe where particles exist in multiple states until observed. This abstract scientific worldview challenges how humans perceive reality and raise questions about whether quantum physics, and scientific frameworks in general, can encapsulate individual’s lived human experience. Amidst this ongoing debate that dates to the 1920s, when quantum physics theories were first proposed by Max Planck, two thinkers across decades offer two competing views. Kurt Riezler, in 1940, critiques quantum physics’ inability to capture lived reality through the psi function’s probabilistic vagueness, the anonymous observer’s displacement of subjectivity, and the Aristotelian call for science rooted in reality. Conversely, Carlo Rovelli, in the 2010s, defends quantum physics through relational ontology, framing its uncertainty as a gateway for imagination and a sign of the universe’s interconnectedness. This paper argues that Rovelli’s interpretation is philosophically rich yet still fails to bridge quantum physics to individual human existence, which was Riezler’s main concern. Despite holding different stances, both thinkers value wonder, humility, and humanity in scientific inquiry and affirms the paper’s broader implication that science and philosophy must work together to reveal universal truths. 

Keywords: Quantum Physics, Psi Function (ψ), Anonymous Observer, Relational Ontology

II. Introduction

The tension between science and philosophy has long centered on the relationship between scientific models and humanity, the lived human experience. This paradox became especially relevant with the rise of quantum physics, which redefined humans’ knowledge of causality and relations. In the early twentieth century, German philosopher and poet Kurt Riezler warned that modern science had grown estranged from its human roots by reducing the universe to probabilities and formulas detached from meaning and purpose and so had quantum physics. On the other hand, contemporary physicist-philosopher Carlo Rovelli embraces the uncertainty of quantum physics, presenting it not as a barrier to human understanding but as an invitation for people to rethink what reality actually is.

This paper argues that Riezler’s Aristotelian standpoint critiques the non-teleological (teleological is a philosophical term denoting the purpose something serves in a material world) nature of quantum physics, its inaccuracy, and its lack of human participation. On the other hand, Rovelli supports quantum physics, believing that its uncertainty philosophically reveals a world woven from interactions. However, I argue that Rovelli’s interpretation does not entirely resolve Riezler’s concern, despite being philosophical and purposeful, as it still fails to resolve the problem of whether quantum physics is linked to everyday individual existence.

Both Rovelli and Riezler share a conviction, rare in scientific discourse, that the pursuit of knowledge is inseparable from the pursuit of happiness. However, their perceptions of happiness diverge: for Riezler, serenity arises from a teleological account of nature grounded in lived experience; for Rovelli, happiness stems from the realization of individuals’ interconnectedness with an indeterminate, relational universe. 

III. Riezler’s Critique of Quantum Physics

1. Probability and the Psi Function (ψ)

Kurt Riezler’s critique of quantum physics stems from its disconnection from human experience and from the universe’s complexity. He argues that scientific equations and probabilities inaccurately account for the human world. He specifically refers to the psi function ψ. In the physics context, the psi function is not the derivative of the logarithm of the gamma function in math, but a wave function that describes a state of a quantum system or a particle. It is used to calculate the probability density of finding a particle with a certain quality or in a particular location (OpenStax, n.d). This wave is something unclear, since, according to Schrodinger’s formula, it evolves unless observed by someone.

First, Riezler explained that the psi function’s probabilistic framework of quantum theory is vague and inaccurate. The psi function does not calculate each event individually but as a wave of probabilities and potential outcomes of the event. “You repeat the same experiment as often as possible,” Riezler observes. “The outcome is a catalogue of various reactions.” (Riezler, 1940, p. [29]). In other words, the experiment does not show what one phenomenon is; it only shows the probabilities of the different outcomes that appeared of that phenomenon. The knowledge thus gained, he writes, is “knowledge about the class to which this element belongs,” not about the element itself (Riezler, 1940, p. [30]). The psi function’s probabilities may describe how often certain results occur, but they cannot tell us the specific implications of each result. 

Moreover, Riezler argues that the psi function oversimplifies and distorts reality’s complexity. “The psi function of quantum theory,” he writes, “base the large world on the small… Thus your science is a mirror inadequate to the object to be reflected” (Riezler, 1940, p. [27-28]). He argues that, rather than deriving its concepts from direct experience of the macroscopic world, quantum physics attempts to build that world out of abstract, artificial tools of the microscopic. The “small” world of particles, which is accessible only through indirect measurement and symbolic modeling, becomes the foundation for explaining the “large” reality. The phrase “base the large world on the small” summarizes the metaphysical absurdity (‘atopan’) Riezler detects in modern science (Riezler, 1940, p. 28). He argues that the microphysical cannot measure the macro world, just as the visible cosmos cannot be explained through invisible constructs. This inversion, for Riezler, is not only epistemological (relating to the theory of knowledge concerning its methods, validity, and scope) but existential: people now seek to investigate the visible through the invisible, the concrete through the hypothetical. 

2. The Anonymous Observer and the Displacement of Subjectivity

Linked to the psi function is Riezler’s notion of the anonymous observer. The “observer” in quantum physics is not a real being with emotions, memory, or moral judgment, but a neutral apparatus. For Riezler, the lack of a conscious mind that performs the measurement is flawed: it assumes that objectivity can exist independently of the subject. But in truth, he argues, the subjective is actually the foundation of the objective in a human-centered world. This inversion also aligns with the etymology of the two words. Subjective comes from the Latin “subicere”—meaning “to throw under,” to lay the foundation upon which one stands—while objective derives from “obicere”––meaning “to throw before,” something which is set out in front of the subjective. The subject, consciousness, is thus the ground, the underlying presence that makes any measured object real. Riezler argues that it is inaccurate to pursue objective knowledge through an “anonymous observer” that lacks a mind since observation, by its nature, implies a standpoint, and standpoints equate subjectivity.

3. Connecting Riezler’s Argument to Ancient Philosophers

Riezler upholds the Aristotelian view of science as an inquiry, a living path that connects natural science, physics, math, ethics, and human beings. According to Schulman Adam Leonin, his essay “Quantum and Aristotelian Physics,” Aristotle’s methodos refers to the “search for knowledge itself, rather than to a set of rules governing the research. Sometimes [Aristotle] speaks not of methodos but simply of hodos, that is, a path or way… Aristotle is always conscious of the danger of too quickly fastening upon technical terms that either fail to capture the phenomena fully or that cover over a problem that deserves further attention. The path to knowledge should repeatedly return to surface impressions to verify that the precision of our principles has not been won at the price of narrowing and distorting our vision” (Schulman, 1989, pp. 9-10). Riezler shares this caution, asserting that inquiry should always link back to lived experience. This verifies that science’s conceptual frameworks do not flatten and distort the way reality functions on an everyday scale. 

Riezler’s critique echoes Aristotle’s notion of theoria (the activity of contemplation as the highest human act) and his own belief in humans’ fundamental desire for knowledge. That is, if people cease to investigate reality by themselves and instead rely on external tools to do so, they diminish their inherent desire for active contemplation. This perspective subtly alludes to Plato’s critique of writing in Phaedrus. Plato argues that writing is an elixir of forgetfulness for the souls that rely on it. This invention strips humans of their active recollection and contemplations as they rely on these external symbols to remember. These ancient philosophers, Aristotle and Plato, were all concerned about the danger of these external tools, whether it is writing or science. 

IV. Rovelli’s Relational Ontology of Quantum Physics and Its Philosophical Implications

Having established Riezler’s concerns about quantum physics’ disconnection from human experience, we now turn to how Rovelli transforms these same uncertainties into philosophical opportunities. Carlo Rovelli’s interpretation of quantum physics begins from an acceptance of uncertainty as an essential feature of the universe, which he perceives as fundamentally relational, not absolute. The term, relational ontology, refers to his view that relations between entities are more important than the identities of the entities. More specifically, Rovelli insists that the foundations of modern physics stemmed not from rigid formulas but from imagination and philosophical vision, the very qualities Riezler championed as meaningful science grounded in human experience. In Reality Is Not What It Seems: The Journey to Quantum Gravity, he asserts that Einstein developed relativity not from equations but from mental images of the universe: “the equations, for him, came afterwards; they were the language with which to make concrete his visions of reality… the theory of general relativity is not a collection of equations: it is a mental image of the world arduously translated into equations” (Rovelli et al., 2018, p. [76]). In other words, Einstein’s insights arose not from mathematical manipulations but from a poetic act of visualization of the universe as a unified fabric of space and time. Through this lens, physics becomes a philosophical, and even aesthetic, endeavor that translates intuition into symbols.

This perspective reverses Riezler’s critique of quantum physics as an abstract catalogue of aggregates detached from lived experience. While Riezler feared that equations stripped humanity, Rovelli views them as a medium of humane imagination. Rovelli finds in quantum physics a form of Romanticism, a reverence for the unseen harmony binding all matters together. In the opening chapter of Reality is Not What it Seems, Rovelli praised Lucretius’ poem “De  Rerum Natura” (“On the Nature of The Universe”)––quoting “we are all sprung from heavenly seed…”––which, in his words, “expresses in luminous verse philosophical questions, scientific ideas, refined arguments” all at once” (Rovelli et al., 2018, p. [20]). He argued that “the beauty of the poem lies in the sense of wonder which pervades the vast atomic vision –– the sense of the profound unity of things, derived from the knowledge that we are all made of the same substance as are the stars, and the sea” (Rovelli et al., 2018, p. [21]). By tracing modern science to ancient philosophical insights of the universe, Rovelli demonstrates how quantum physics, far from being only a statistical tool, is a philosophical exploration of the universe’s interconnectivity.

Paul Dirac’s principle of superposition illustrates the interconnectedness of imagination and precision. According to Dirac, a quantum entity such as a photon exists in multiple possible states simultaneously until measured. The double-slit experiment, which demonstrates that photons and electrons behave as both waves and particles, exemplifies this insight. When photons or electrons pass through two slits unobserved, they produce an interference pattern, behaving as waves distributed across space. Yet, when one just looks to see or anticipates which slit they pass through, the interference vanishes; the pattern collapses into two discrete bands. This wave-particle duality overthrows our understanding of the traditional wave function and Riezler’s argument about the anonymous observer. Here, the very act of observation transforms what is observed. 

Another experiment that addresses the inseparable relationship between the observed and the observer is Schrödinger’s cat (1935). The experiment involves a cat sealed in a box with a radioactive atom, a Geiger counter, a hammer, and poison. The atom’s decay is governed by quantum probability (50% chance of decay): it may or may not release radiation that would kill the cat in a given time frame. The cat is neither definitively alive nor dead, suspended in a superposition of both possibilities, until an observer opens the box. This experiment shows that quantum states are undetermined until observed. As Rovelli explains in Helgoland, “facts that are real with respect to an object are not necessarily so with respect to another” (Rovelli et al., 2022, p. [72]). The radiation emitted by the atom, as Rovelli emphasizes, does not have a definite value until it affects another system. The fate of the cat is indeterminate until relations between the atom, the cat, and the observer are established. In this framework, reality emerged only through interactions. 

As the psychologist Amos Tversky puts it, “reality is a cloud of possibility, not a point” (Stockton, 2017). The analogy of reality to misty clouds in a blurred photograph captures the ambiguity of this relational world: when an image appears unclear, one may ask whether the blur arises from the photographer’s unsteady hands or from the mist itself. For Rovelli, this distinction collapses as the uncertainty belongs to the act of seeing as much as to the seen. Reality’s imperfection is an intrinsic quality of existence.

The indeterminacy of all things in the absence of relational context challenged earlier philosophers and scientists, such as Newton and Hobbes. They envisioned a universe governed by immutable laws. They sought to dispel the “clouds” since truth resided in the elimination of ambiguity. Rovelli’s argument of quantum physics, however, weaves the uncertainty as an essential part of truth. Thus, Rovelli’s quantum mechanical worldview dissolves the Cartesian boundary between subject and object, suggesting instead a universe intertwined with relations.

In psychological terms, this relational worldview connects to human serenity. For Rovelli, serenity arises not from mastering the world but from recognizing one’s belonging within an interdependent universe and one’s ignorance amidst its complexity. This feeling of serenity, which stems from recognition of one’s ignorance, aligns with ancient philosophers such as Socrates and Confucianism. In Plato’s Apology, Plato wrote Socrates’ assertion that “I am wisest of all the Greeks because that which I do not know, I do not think I know either” (Plato, n.d., p. 83). Therefore, to live, as Rovelli suggests, is to dwell within the cloud of possibilities and to accept the world not as a set of certainties but as a field of relations continuously unfolding.

In the closing pages of Helgoland, Rovelli turns to Shakespeare’s The Tempest, quoting Prospero’s famous farewell: 

“These are actors,

As I foretold you, were all spirits and

Are melted into air, into thin air:

And, like the baseless fabric of this vision…

Yea, all which it inherit, shall dissolve.

And like this insubstantial pageant faded,

Leave not a rack behind. We are such stuff

As dreams are made on, and our little life 

Is rounded with sleep.”

The quotation encapsulates Rovelli’s vision of reality as transient, woven of relations that shimmer briefly before dissolving. The last sentence echoes Rovelli’s belief in “confirmed hallucination.” This concept echoes 19th-century French philosopher Hippolyte Taine’s insight that “external perception is an internal dream which proves to be in harmony with external things.” Like the character Prospero’s vision of life as a dream sustained by momentary harmony, Rovelli’s universe is a network of fleeting interactions whose beauty lies in their impermanence. 

However, even Rovelli does not resolve Riezler’s question about quantum physics’ inability to capture the full depths and dimensions of the universe, which, I believe, is incapable to be explained even by modern philosophy and technology. It requires the ongoing, collaborative research of both philosophy and science, fields that are deeply connected.

V. Conclusion

In the end, Rovelli concedes that the reach of quantum physics is not unlimited. He fails to see any quantum explanation for subjectivity, perceptions, intelligence, consciousness, or any other aspects of our mental life. Quantum phenomena intervene in the dynamics of atoms, photons, electromagnetic impulses, and all other microscopic structures that give rise to our body, but there is nothing specifically quantum that could help us understand what thoughts, perception, and subjectivity are. Even in a neuroscience context, neurons and their signaling molecules are too large for quantum phenomena to play a role in their functioning, as expressed by Daniel Demmet. He stated, “Most biologists think that quantum effects all just cancel out in the brain, that there’s no reason to think they’re harnessed in any way. Of course they’re there; quantum effects are there in your car, your watch, and your computer. But most things — most macroscopic objects — are, as it were, oblivious to quantum effects.” (Penrose and Dennett, 1995). This acknowledgement is not a defeat, but a recognition that even the most sophisticated physics does not unravel the mystery of consciousness. 

Riezler would have regarded this concession as proof that the essence of human existence, with its moral, existential dimensions, lies beyond the restriction of theoretical science. But Rovelli views this limitation as a form of serenity. For him, the inability of quantum physics to explain human experience does not diminish its depth. Nevertheless, the distance between Riezler and Rovelli may not be as great as it first appears. Both reject the illusion of absolute mastery of the universe and support an ideal form of science rooted in wonder, humility, and humanity. To me, quantum physics does not need to fully explain the universe and our consciousness to be valuable. 

VI. References

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Lewis, M. (2017). The Undoing Project: A Friendship that Changed our Minds. W.W. Norton & Company.

OpenStax (Ed.). (n.d.). 7.2: Wave Functions. LibreTexts Physics. https://phys.libretexts.org/Bookshelves/University_Physics/University_Physics_(OpenStax)/
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Plato. (n.d.). Plato, Euthyphro. Apology. Crito. Phaedo: Apology (H. N. Fowler, Trans.). Loeb Classical Library.

Riezler, K. (1940). Physics and Reality: Lectures of Aristotle on Modern Physics. Yale University Press.

Rovelli, C., Carnell, S., & Segre, E. (2018). Reality is not What it Seems: the Journey to Quantum Gravity. Riverhead Books.

Rovelli, C., Segre, E., & Carnell, S. (2022). Helgoland: making sense of the quantum revolution. Riverhead Books.

Schulman, A. L. (1989). Quantum and Aristotelian Physics. Harvard University ProQuest Dissertations & Theses.

Stockton, S. S. (Ed.). (2017, September 9). Living in a Cloud of Possibilities. Retrieved November 25, 2025, from https://intrinsicinvesting.com/2017/09/29/living-cloud-possibilities/

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