This brochure gathers three connected but non-identical interventions into Arkady Plotnitsky’s philosophical field. Together they move from non-representation to filtration, from ambiguity and decision to filtrational topology, and from reality without realism to admissibility without representational primacy. The central claim is that the decisive quantum break should not be understood only as the withdrawal of reality from representation, but as the displacement of representation from the primary level of analysis. What takes its place is an operatorial regime of admissibility governing which events, transitions, measurements, and correlations can become locally stable and formally articulable. In this way, Plotnitsky’s framework is not rejected but transformed: its strongest insights are preserved, while their limits are exposed and recoded through the conceptual grammar of Possest–PQF. Keywords Plotnitsky; Possest–PQF; quantum theory; reality without realism; admissibility; filtration; Heisenberg; matrix mechanics; complementarity; philosophy of physics
This brochure gathers three connected but non-identical interventions into Arkady Plotnitsky’s philosophical field. Together they move from non-representation to filtration, from ambiguity and decision to filtrational topology, and from reality without realism to admissibility without representational primacy. The central claim is that the decisive quantum break should not be understood only as the withdrawal of reality from representation, but as the displacement of representation from the primary level of analysis. What takes its place is an operatorial regime of admissibility governing which events, transitions, measurements, and correlations can become locally stable and formally articulable. In this way, Plotnitsky’s framework is not rejected but transformed: its strongest insights are preserved, while their limits are exposed and recoded through the conceptual grammar of Possest–PQF. Keywords Plotnitsky; Possest–PQF; quantum theory; reality without realism; admissibility; filtration; Heisenberg; matrix mechanics; complementarity; philosophy of physics
For many years, Arkady Plotnitsky has written extensively about the interpretation of quantum mechanics, and his source of inspiration has undoubtedly been Niels Bohr’s philosophy to which he has returned time and again in order to make clear what Bohr said and meant. More than many other philosophers, Plotnitsky’s work shows a deep understanding of quantum mechanics and of Bohr’s thinking especially. In the present paper, he attempts to give a rational reconstruction of what he sees as Heisenberg’s Pythagorean revolution. This he explains as Heisenberg’s aim in his search for a theory. Heisenberg was looking for “a strictly predictive theory of quantum phenomena (only probabilistically predictive on the experimental grounds), without requiring this theory to represent the ultimate reality responsible for quantum phenomena. This is the form of Pythagorean view that this article advocates under the heading of the ‘reality-without-realism’ (RWR) Pythagorean view, also possible in mathematics”. Unfortunately, I think that Plotnitsky’s rational reconstruction misses some important historical facts just as I think the expression “ultimate reality” is unfortunate. Rejecting that our physical theories represent a world beyond the phenomena does not imply that there is something left to be represented in the future.
Complementarity and Deconstruction: Plotnitsky's Analysis and Beyond Makoto Katsumori Akita University The philosophical thought of the modern physicist Niels Bohr (1885–1962), which revolves around the concept of complementarity, has long been a major subject of historical and philosophical inquiry. Many prior studies of Bohr's complementarity, however, seem to be limited by the fact that they largely proceed within the conceptual frames of the "mainstream" philosophy of science. This being the case, his radical questioning of traditional scientific and philosophical notions—such as the unambiguity of concepts and words—has not been adequately addressed, insofar as these notions are uncritically presupposed by the commentators themselves. In other words, Bohr's thought has often been interpreted under certain tacit premises of scientific rationality that are precisely of the kind targeted by his epistemological critique. In recent years, however, there have emerged new approaches to Bohr's idea of complementarity that place it in different, less conventional, philosophical contexts. Among the most notable of these is Arkady Plotnitsky's endeavor to connect Bohr's complementarity with Jacques Derrida's project of deconstruction. In the present article, based on my recent doctoral dissertation,1 I take up this contribution by Plotnitsky as a suitable point of reference from which to [End Page 435] explore anew Bohr's thought with its radical philosophical implications. After outlining Bohr's complementarity argument and Plotnitsky's reading thereof (in the first and second sections, respectively), I will examine a series of problems that seem to face, or to be left unsolved by, Plotnitsky's account (in the third section). This critical appraisal will finally lead me to sketch a new interpretive approach of my own (in the fourth section), which both extends and delimits the intersections between complementarity and deconstruction. As regards the historical development of Bohr's complementarity, I will largely restrict myself to the period between 1927 and 1950, in which the most crucial of his innovative ideas seem to have been presented. I. Bohr's Idea of Complementarity In his 1927 lecture delivered in Como, Italy, entitled "The Quantum Postulate and the Recent Development of Atomic Theory," Niels Bohr introduced the concept and framework of complementarity as a pivotal idea in his interpretation of quantum theory. From then on, he continually developed the idea of complementarity with regard not only to quantum theory but to other fields of knowledge as well. In what follows, I will first outline his complementarity argument in its "early" period, stretching from 1927 to the mid-thirties,—or, more precisely, until just before his 1935 debate with EPR.2 Bohr starts by noting that "our usual description of physical phenomena is based entirely on the idea that the phenomena concerned may be observed without disturbing them appreciably."3 This notion of physical phenomena as undisturbed by observation underlies all of classical physics and is still maintained in the theory of relativity. However, Bohr continues, a new situation has arisen with the development of quantum theory, specifically with "the so-called quantum postulate, which attributes to any atomic process an essential discontinuity, or rather individuality, completely foreign to the classical theories"; this "individuality" implies that "any observation of atomic phenomena will involve an interaction with the [End Page 436] agency of observation not to be neglected" (PWNB, 1: 53–54.). In more specific terms, any observation aimed at space-time coordination brings about an exchange of momentum and energy with the measuring rods and clocks. It is crucial here that this interaction between the object and the instrument of observation is not simply unavoidable, but "uncontrollable," which represents a "feature of irrationality" brought into the description of nature (PWNB, 1: 68, 91). For insofar as the measuring instruments are to fulfill their purpose, the interaction itself cannot be taken into account, and thus the magnitude of the disturbance always remains unknown. It follows, in Bohr's view, that "an independent reality in the ordinary physical sense can neither be ascribed to the phenomena nor to the agencies of observation...
The innovations to physics introduced by Werner Heisenberg and Niels Bohr via quantum mechanics presented them with epistemological and metaphysical challenges with which they were perpetually engaged. Among Heisenberg’s innovations are the complex-valued quantum state-transition probability amplitudes, and among Bohr’s the non- trivial role of the measuring environment in the procurement of data. In his article, Arkady Plotnitsky examines the responses of these two natural philosophers to these challenges through the lens of Pythagoreanism in terms of the rational and the irrational. He argues that Bohr’s philosophical stance is of the Reality-without-Realism sort in that Bohr holds quantum reality to be unrepresentable, and that Heisenberg’s is of the Pythagorean-realist sort in that Heisenberg comes to hold reality to be representable, but only by mathematics. Here, I argue that Heisenberg’s later representation of reality can be characterized as neo- Aristotelian because, among other relevant things, he intentionally develops quantum potentiality, which is essential to his late interpretation of the quantum formalism, as a quantification of Aristotle’s potentia.
We have referred to general organising principles of quantum mechanics (QM) in the previous chapter, which can be extended (as principles) to several other domains. Among such principles, contextuality-complementarity is perhaps most important in its applicability to different domains of reality. There is a consensus now ( Khrennikov, 2022 ) that these principles emerged through the original works of N. Bohr. Khrennikov (2025) has produced a seminal work in which contextuality becomes the basis of reformulation of QM, and even non-locality, which is argued to be a central feature in the orthodox QM interpretation (rather than the Copenhagen(ish) approaches), can also be reformulated in terms of local contextuality. We will hold a different approach to non-locality later in the chapter, which builds upon our earlier works ( Nadeau and Kafatos, 2001 ). We also mention here that some authors ( Plotnitsky, 2022 ) have attempted to formulate a ‘reality without realism’ view based on Bohr’s original insights. In this chapter, we provide a more detailed view of Copenhagen(ish) approaches to contextuality-complementarity. Since we think that a quantum-like framework (QLF) is also related to such approaches, contextuality-complementarity in QLF can also be formulated in the same line.
By questioning the validity of some of our basic concepts, such as space, object, and causality, quantum physics contributes quite decisively to the dramatic changes now taking place in our world picture.This book is addressed not only to physicists at an early stage in their careers (the first or second year graduate student) but also to philosophers, as well as to all the senior physicists interested in the interpretation problem. Beginning with a chapter that could be described as ?philosophy for physicists,? it presents an in-depth analysis of present-day quantum mechanical concepts, an analysis of physicists and philosophers alike. Specifically, it first offers an extensive critical analysis of such topics as the Einstein, Podolsky, Rosen reality criterion, nonseparatability, the quantum measurement riddle, decoherence theory, consistent histories approaches and ontologically interpretable theories. All this then naturally leads to philosophical questions concerning, in particular, intersubjective agreement and the limit of realism. And a thorough examination of this whole material finally leads to the view that distinguishing between empirical reality and a veiled man-independent reality yields an acceptable answer to the perplexing question of how to interpret quantum physics. Veiled Reality offers nonspecialists, including students in physics, philosophy and the history of science, an accessible perspective on basic problems in the foundations of physics.
Abstract This paper reconstructs the q-desic proposal in quantum gravity as a warning against premature averaging. Its central claim is not merely that geodesics receive quantum corrections, but that the order of reduction matters: varying first and averaging later yields trajectories that are not equivalent to those obtained by first averaging the metric and only afterward deriving the equation of motion. The significance of this non-equivalence exceeds its immediate gravitational setting. The paper therefore does two things at once. First, it isolates the formal core of the q-desic mechanism by showing that the expectation value of the connection operator cannot, in general, be reduced to the classical connection computed from the expectation value of the metric. Second, it argues that this distinction has a broader methodological and philosophical force: average structure is not identical with average action. On that basis, the paper develops a procedural reading of q-desics in which horizon shifts and modified orbital motion are treated as consequences of non-innocent reduction rather than as isolated technical corrections. It then extends the discussion beyond quantum gravity by identifying a transferable operatorial pattern relevant to any domain in which early averaging risks erasing the law-producing mechanism. In a final step, the q-desic construction is interpreted through a Possest–PQF lens, where motion is no longer treated as transport across a fully pre-given background but as the downstream effect of a regime of local admissibility. The paper does not claim that q-desics are already PQF. It argues instead for a structural homology between operatorially corrected motion and filtrational accounts of trajectory production. The result is a conceptual intervention into the logic of reduction, admissibility, and the formation of observable paths. Keywords q-desics, quantum gravity, geodesics, operator ordering, premature averaging, expectation value, connection operator, covariance term, admissible motion, filtrational topology, Possest-PQF,philosophy of physics