Quantum mechanics reconfigures classical assumptions about objectivity by showing that physical description cannot be separated from the processes through which phenomena become intelligible. While Niels Bohr is often read as an instrumentalist or cautious anti-realist, this paper argues instead that his account of measurement advances a transcendental analysis of the conditions under which physical properties can count as objective at all. On this reading, complementarity is not a limit on access to an underlying reality, but a constraint on the forms of description through which physical properties become determinate and communicable. Drawing on a neo-Kantian perspective, I argue that objectivity in quantum theory is neither representational nor observer-independent but is realised through participatory conditions that anchor physical meaning within shared spatio-temporal and causal frameworks. The slogan ‘to be is to measure’ is defended as shorthand for the claim that objective physical properties are not revealed as pre-existing features of nature but arise only within experimental contexts that disclose them as intelligible objects within a shared mode of possible experience.
Quantum mechanics reconfigures classical assumptions about objectivity by showing that physical description cannot be separated from the processes through which phenomena become intelligible. While Niels Bohr is often read as an instrumentalist or cautious anti-realist, this paper argues instead that his account of measurement advances a transcendental analysis of the conditions under which physical properties can count as objective at all. On this reading, complementarity is not a limit on access to an underlying reality, but a constraint on the forms of description through which physical properties become determinate and communicable. Drawing on a neo-Kantian perspective, I argue that objectivity in quantum theory is neither representational nor observer-independent but is realised through participatory conditions that anchor physical meaning within shared spatio-temporal and causal frameworks. The slogan ‘to be is to measure’ is defended as shorthand for the claim that objective physical properties are not revealed as pre-existing features of nature but arise only within experimental contexts that disclose them as intelligible objects within a shared mode of possible experience.
Abstract Niels Bohr is standardly read as an instrumentalist or a cautious anti-realist. By way of a rational reconstruction, I argue that his philosophy of experiment advances a transcendental account of the conditions under which physical properties can count as objective at all. On this view, complementarity constrains the forms of description through which physical properties become determinate and communicable. Existing transcendental readings stop at this point; I argue that his philosophy of experiment contains the resources to go further. Objectivity is not merely constituted by such conditions but physically enacted through the observer’s choice of experimental context. This means moving beyond representational and observer-independent forms of realism and adopting a participatory realism in which objectivity is reconceived as the intersubjective stability across observers who experiment (and thus experience) within a shared mode of possible experience. The slogan ‘to be is to measure’ is not defended as an ontological thesis but as shorthand for the claim that physical properties become determinate only within experimental contexts that embodied observers of a particular class enact and share.
In the Critique of Pure Reason Kant argues that the empirical knowledge of the world depends on a priori conditions of human sensibility and understanding, i. e., our capacities of sense experience and concept formation. The objective knowledge presupposes, on one hand, space and time as a priori conditions of sensibility and, on another hand, a priori judgments, like the principle of causality, as constitutive conditions of understanding. The problem is that in the XX century the physical science completely changed how we conceive our knowledge of the world. Face to this new situation, what was changed in our classical reason? However, if the transcendental point of view is adopted, in the specific case of quantum mechanics, we have to wonder about the general conditions of this theory that make possible such knowledge, which predictive value is much more accurate than the classical physics. The aim of this work is firstly to show the Kantian implications on Bohr’s interpretation of quantum phenomena and secondly to provide an overview of the key elements for understanding the transcendental locus of ordinary language in the quantum mechanics context, in order to give support to a transcendental pragmatic position in the analysis of science.
Abstract: In the Critique of Pure Reason Kant argues that the empirical knowledge of the world depends on a priori conditions of human sensibility and understanding, i. e., our capacities of sense experience and concept formation. The objective knowledge presupposes, on one hand, space and time as a priori conditions of sensibility and, on another hand, a priori judgments, like the principle of causality, as constitutive conditions of understanding. The problem is that in the XX century the physical science completely changed how we conceive our knowledge of the world. Face to this new situation, what was changed in our classical reason? However, if the transcendental point of view is adopted, in the specific case of quantum mechanics, we have to wonder about the general conditions of this theory that make possible such knowledge, which predictive value is much more accurate than the classical physics. The aim of this work is firstly to show the Kantian implications on Bohr’s interpretation of quantum phenomena and secondly to provide an overview of the key elements for understanding the transcendental locus of ordinary language in the quantum mechanics context, in order to give support to a transcendental pragmatic position in the analysis of science.
I flesh out the sense in which the informational approach to interpreting quantum mechanics, as defended by Pitowsky and Bub and lately by a number of other authors, is (neo-)Bohrian. I argue that on this approach, quantum mechanics represents what Bohr called a "natural generalisation of the ordinary causal description" in the sense that the idea (which philosophers of science like Stein have argued for on the grounds of practical and epistemic necessity) that understanding a theory as a theory of physics requires that one be able to "schematise the observer" within it is elevated in quantum mechanics to the level of a postulate in the sense that interpreting the outcome of a measurement interaction, as providing us with information about the world, requires as a matter of principle, the specification of a schematic representation of an observer in the form of a 'Boolean frame'-the Boolean algebra representing the yes-or-no questions associated with a given observable representative of a given experimental context. I argue that the approach's central concern is with the methodological question of how to assign physical properties to what one takes to be a system in a given experimental context, rather than the metaphysical question of what a given state vector represents independently of any context, and I show how the quantum generalisation of the concept of an open system may be used to assuage Einstein's complaint that the orthodox approach to quantum mechanics runs afoul of the supposedly fundamental methodological requirement to the effect that one must always be able, according to Einstein, to treat spatially separated systems as isolated from one another.
Kant’s philosophy of science has been applied to quantum physics since the time when Niels Bohr formulated his interpretation of quantum physics. In recent years various Kantian interpretations of quantum physics have been put forward. One aspect that still needs further exploration is what a Kantian approach to the epistemic status of quantum entities would entail. In this paper a new kind of judgment consistent with Kant’s system, called a transcendental judgment, able to account for the real existence of quantum entities in the pre-measurement phase is discussed. The advantage of this kind of judgment is that it allows for a fine-tuning of the Kantian system to account for the discovery of quantum entities that are known to exist but whose existence can epistemologically not be accounted for in traditional Kantian philosophy. With this new kind of judgment, a wider range of possible judgments becomes available which can determine the epistemological status of concepts/ideas/theories quite carefully, discriminating between different kinds of knowledge claims.
This article reconsiders the concept of physical reality in quantum theory and the concept of quantum measurement, following Bohr, whose analysis of quantum measurement led him to his concept of a (quantum) "phenomenon," referring to "the observations obtained under the specified circumstances," in the interaction between quantum objects and measuring instruments. This situation makes the terms "observation" and "measurement," as conventionally understood, inapplicable. These terms are remnants of classical physics or still earlier history, from which classical physics inherited it. As defined here, a quantum measurement does not measure any preexisting property of the ultimate constitution of the reality responsible for quantum phenomena. An act of measurement establishes a quantum phenomenon by an interaction between the instrument and the quantum object or in the present view the ultimate constitution of the reality responsible for quantum phenomena and, at the time of measurement, also quantum objects. In the view advanced in this article, in contrast to that of Bohr, quantum objects, such as electrons or photons, are assumed to exist only at the time of measurement and not independently, a view that redefines the concept of quantum object as well. This redefinition becomes especially important in high-energy quantum regimes and quantum field theory and allows this article to define a new concept of quantum field. The article also considers, now following Bohr, the quantum measurement as the entanglement between quantum objects and measurement instruments. The argument of the article is grounded in the concept "reality without realism" (RWR), as underlying quantum measurement thus understood, and the view, the RWR view, of quantum theory defined by this concept. The RWR view places a stratum of physical reality thus designated, here the reality ultimately responsible for quantum phenomena, beyond representation or knowledge, or even conception, and defines the corresponding set of interpretations quantum mechanics or quantum field theory, such as the one assumed in this article, in which, again, not only quantum phenomena but also quantum objects are (idealizations) defined by measurement. As such, the article also offers a broadly conceived response to J. Bell's argument "against 'measurement'".