The successful application of quantum probability in cognitive science has been persistently challenged by the foundational 'why quantum?' question. In this paper, a novel answer is proposed through the development of an ontological grounding for the quantum-like structures observed in human judgment. It is argued that these cognitive structures may be a direct reflection of an objective, information-theoretic vagueness inherent in the macroscopic world. To formalize this, 'Quantized Mereology' is developed - a framework inspired by Rovelli's Relational Quantum Mechanics (RQM), where determinate mereological facts about vague entities like forests and clouds are established relationally through an act of judgment. The framework uses a real-valued Hilbert space as a precise object language, which is given meaning by a partition-theoretic meta-language. A key contribution is a defense of the real-valued structure, in which it is argued that the physical constraints necessitating complex numbers in microphysics constitute a category error when applied to the conceptual systems modeled herein. The result is a generative model for objective vagueness that provides a candidate ontological foundation for quantum cognition.
The successful application of quantum probability in cognitive science has been persistently challenged by the foundational 'why quantum?' question. In this paper, a novel answer is proposed through the development of an ontological grounding for the quantum-like structures observed in human judgment. It is argued that these cognitive structures may be a direct reflection of an objective, information-theoretic vagueness inherent in the macroscopic world. To formalize this, 'Quantized Mereology' is developed - a framework inspired by Rovelli's Relational Quantum Mechanics (RQM), where determinate mereological facts about vague entities like forests and clouds are established relationally through an act of judgment. The framework uses a real-valued Hilbert space as a precise object language, which is given meaning by a partition-theoretic meta-language. A key contribution is a defense of the real-valued structure, in which it is argued that the physical constraints necessitating complex numbers in microphysics constitute a category error when applied to the conceptual systems modeled herein. The result is a generative model for objective vagueness that provides a candidate ontological foundation for quantum cognition.
Qualitative representations of mereological structures in Artificial Intelligence are generally based on a set of mutually exclusive and collectively exhaustive crisp (RCC5) relations. The amount of information carried by each element in this set of (crisp) relations is determined by the number of bits (N) required to distinguish all members of the set. This paper posits that mereological vagueness can arise if mereological relations are limited in the amount of information they can carry. Consequently, a comprehensive set of vague mereological relations is introduced, where each relation in this set can only carry 0 < n < N bits of information. In this framework, mereological information is treated as quantum information, with quantum bits (qubits) distinguishing relations subject to ontic vagueness. The main contribution is the thorough examination of mereological relations within a 3 qubit quantum system. Quantum bits are not represented as vectors in a Hilbert space but as cells in (granular) partitions. This paper is the companion to the author's quantized-mereology framework and develops its entangled-state layer: the combination of three simultaneous elementary questions, the families of entangled information states, the probability distribution for possible observations and the dynamics induced by sequences of non-simultaneous questions.
This paper investigates quantized mereology, which merges quantum information theory with classical mereology, the formal analysis of the part-whole relationship. It emphasizes that information about crisp mereological relations is captured by classical bits, whereas mereological vagueness involves the use of quantum bits, or qubits, to capture mereological information. Transitioning from classical bits to qubits offers a new understanding of part-whole relations among entities that are subject to mereological vagueness. This paper methodically studies the quantized mereology that arises from the classical RCC5 formalism, one of the most widely studied formalisms in Qualitative Reasoning (QR), a subfield of Artificial Intelligence. The argument is made that this method can be extended to quantize more sophisticated QR formalisms, mirroring how strategies are used in physics to transition from classical to quantum systems. The study explores: (i) the conversion of bits to qubits while understanding that these (qu)bits convey mereological information; (ii) the representation of qubit states via set partitions, acknowledging that set theory aligns more closely with classical logic than with the complex vector spaces employed in quantum physics; (iii) demonstrating that classical QR formalisms can be seen as special cases within quantized formalisms; and (iv) showing that qubits more effectively encapsulate information about vague phenomena.
The present essay provides a new metaphysical interpretation of Relational Quantum Mechanics (RQM) in terms of mereological bundle theory. The essential idea is to claim that a physical system in RQM can be defined as a mereological fusion of properties whose values may vary for different observers. Abandoning the Aristotelian tradition centered on the notion of substance, I claim that RQM embraces an ontology of properties that finds its roots in the heritage of David Hume. To this regard, defining what kind of concrete physical objects populate the world according to RQM, I argue that this theoretical framework can be made compatible with (i) a property-oriented ontology, in which the notion of object can be easily defined, and (ii) moderate structural realism, a philosophical position where relations and relata are both fundamental. Finally, I conclude that under this reading relational quantum mechanics should be included among the full-fledged realist interpretations of quantum theory.
This paper examines the metaphysical foundations of Relational Quantum Mechanics (RQM), with special attention to its compatibility with scientific realism. We argue that RQM faces a dilemma. In its original formulation, RQM secures a sparse ontology of relative quantum events, but lacks the world-building structure needed to explain how these events jointly constitute a single, coherent reality of the kind presupposed by scientific realism. Recent discussions have already emphasized the difficulties that RQM faces concerning intersubjective agreement, communication, and the emergence of stable facts. Our contribution is to diagnose these difficulties as symptoms of a deeper metaphysical problem: RQM provides relative facts, but no clear account of what makes them facts of one world. We then assess the revised formulation proposed by Adlam and Rovelli, centered on the Cross-Perspective Links (CPL) principle. While CPL aims to restore intersubjective agreement by guaranteeing consistency across perspectives, we argue that it does so at a significant cost. It introduces observer-independent facts, persistent information-bearing structures, and global consistency constraints that sit uneasily with the relational spirit of the original interpretation. Thus, RQM either remains thoroughly relational but metaphysically too weak to support robust scientific realism, or it repairs this weakness by compromising its own relational foundations.
Quantum mechanics is among the most successful mathematical frameworks in modern science, providing precise predictions, experimental validation, and wide-ranging technological applications. This success, however, has been accompanied by a long-standing suspension of a fundamental question: the ontological status of quantum itself. While dominant approaches emphasize how quantum phenomena behave, the question of what these behaviors are the behavior of has largely been deferred. This work does not propose a new physical theory, nor does it challenge the empirical or mathematical foundations of quantum mechanics. Instead, it offers an ontological positioning that reintroduces the question of ground. Quantum is approached neither as a discrete object nor as a purely mathematical formalism, but as the joint mode of operation of energy, nature, and consciousness. Within this framework, consciousness is not treated as an external causal agent acting upon physical systems, but as an immanent, organizing, and meaning-generating aspect of energetic continuity. Differentiation is thus located not in nature itself, but at the level of meaning. Observation and measurement are reinterpreted accordingly, not as mechanisms of physical collapse, but as processes through which ontological distinctions become articulated. By reframing quantum as a ground rather than a thing, this study aims to clarify persistent conceptual tensions—such as the observer problem and the status of measurement—without invoking speculative physics or metaphysical dualism. The paper presents not a solution, but a repositioning: an invitation to reconsider the ontological assumptions that guide contemporary readings of quantum mechanics.
Abstract The following paper explores the metaphysical significance of Relational Quantum Mechanics (RQM). For this, I will first outline Rovelli’s philosophical framework, and then offer a reconstruction of Rovelli’s seminal argument in favour of RQM. I will then explore some healthy lines of philosophical work that may be undertaken to strengthen RQM. First, I will frame RQM in the debate between realist and antirealist readings of QM and defend the general claim that RQM is compatible with realism. Then, I discuss the main ontological interpretations of RQM, which I classify as “dispositional”, “transcendental” and “structural”, and argue that all of them remain committed to substantialist assumptions that limit the radicality of Rovelli’s proposal. Finally, I analyse recent developments on RQM’s ontology and suggest that preserving its ontological originality requires an assessment on the concept of “pattern”.