In this paper, I argue that Heisenberg's mature philosophy of quantum mechanics must be understood in the context of his epistemological project to reinterpret and redefine Kant's notion of the a priori. After discussions with Weizsäcker and Hermann in Leipzig in the 1930s, Heisenberg attempted to ground his interpretation of quantum mechanics on what might be termed a 'practical' transformation of Kantian philosophy. Taking as his starting point, Bohr's doctrine of the indispensability of classical concepts, Heisenberg argued that concepts such (...) as space, time and causality can be regarded as 'practically a priori', in so far as they remain the conditions for the possibility of experience and even of 'objective reality', though they are not universal and necessary in a strictly Kantian sense. We cannot avoid using classical concepts in the description of experiments in quantum theory, despite the fact that there are limits to their applicability. Such concepts are, for Heisenberg, historically contingent, yet indispensable in our time, because we have no other language through which we can describe and conceive of the interaction between 'object' and 'measuring device'. (shrink)

The ArgumentThe aim of this paper is to provide a critical perspective for Einstein's opposition to the Copenhagen interpretation of quantum physics, by analyzing the ingenious rhetoric of Bohr's principle of complementarity. I argue that what Bohr presents as arguments of “inevitability” are in fact merely arguments for the consistency of the quantum-mechanical scheme. Einstein's resistance to being persuaded by this potent technique of argumentation, and his rejection of Bohr's interpretation of quantum physics, appear consequently as an eminently reasonable position (...) and not as a conservative stand, as it is often presented by the adherents of the Copenhagen orthodoxy. (shrink)

In 1957, Feyerabend delivered a paper titled ‘On the Quantum-Theory of Measurement’ at the Colston Research Symposium in Bristol to sketch a completion of von Neumann's measurement scheme without collapse, using only unitary quantum dynamics and well-motivated statistical assumptions about macroscopic quantum systems. Feyerabend's paper has been recognised as an early contribution to quantum measurement, anticipating certain aspects of decoherence. Our paper reassesses the physical and philosophical content of Feyerabend's contribution, detailing the technical steps as well as its overall philosophical (...) motivations and consequences. Summarising our results, Feyerabend interpreted collapse as a positivist assumption in quantum mechanics leading to a strict distinction between the uninterpreted formalism of unitary evolution in quantum mechanics and the classically interpreted observational language describing post-measurement outcomes. Thus Feyerabend took the no-collapse completion of the von Neumann measurement scheme to show the dispensability of the positivist assumption, leading the way to a realistic interpretation of quantum theory. We note, however, that there are substantial problems with his account of measurement that bring into question its viability as a legitimate foil to the orthodox view. We further argue that his dissatisfaction with the von Neumann measurement scheme is indicative of early views on theoretical pluralism. (shrink)

This paper puts forward an ontology that is indebted to QBism, Kant, Bohr, Schrödinger, the philosophy of the Upanishads, and the evolutionary philosophy of Sri Aurobindo. Central to it is that reality is relative to consciousness or experience. Instead of a single mind-independent reality, there are different poises of consciousness, including a consciousness to which “we are all really only various aspects of the One”. This ontology helps clear up unresolved issues in the philosophy of science, such as arise from (...) the reification of quantum states or from disregard of the universal context of science, which is human experience. It further helps clear up unresolved issues in the philosophy of mind, in particular the problem of intentionality and the dilemma posed by the mutual inclusion of self and world. (shrink)

In this paper, I challenge the traditional narrative that William James’s arguments against determinism were primarily motivated by his personal struggles with depression. I argue that James presents an alternative argument against determinism that is motivated by his commitment to sound scientific practice. James argues that determinism illegitimately extrapolates from observations of past events to predictions about future events without acknowledging the distinct metaphysical difference between them. This occupation with futurity suggests that James’s true target is better understood as logical (...) determinism rather than causal determinism. This has consequences for James’s proposed alternative, which I call his probabilistic underdeterminism, a conception of the universe that is built on chance, choice, and a local teleology. All of this forms part of a broader criticism of the scientific practices of his day based on their widespread failure to acknowledge the distorting effects of observation on that which is observed. (shrink)

Niels Bohr’s complementarity principle is a tenuous synthesis of seemingly discrepant theoretical approaches based on a comprehensive analysis of relevant experimental results. Yet the role of complementarity, and the experimentalist-minded approach behind it, were not confined to a provisional best-available synthesis of well-established experimental results alone. They were also pivotal in discovering and explaining the phenomenon of quantum tunneling in its various forms. The core principles of Bohr’s method and the ensuing complementarity account of quantum phenomena remain highly relevant guidelines (...) in the current controversial debate and in experimental work on quantum tunneling times. (shrink)

I argue that instead of a rather narrow focus on N. Bohr's account of complementarity as a particular and perhaps obscure metaphysical or epistemological concept (or as being motivated by such a concept), we should consider it to result from pursuing a particular method of studying physical phenomena. More precisely, I identify a strong undercurrent of Baconian method of induction in Bohr's work that likely emerged during his experimental training and practice. When its development is analyzed in light of Baconian (...) induction, complementarity emerges as a levelheaded rather than a controversial account, carefully elicited from a comprehensive grasp of the available experimental basis, shunning hasty metaphysically motivated generalizations based on partial experimental evidence. In fact, Bohr's insistence on the “classical” nature of observations in experiments, as well as the counterintuitive synthesis of wave and particle concepts that have puzzled scholars, seem a natural outcome (an updated instance) of the inductive method. Such analysis clarifies the intricacies of early Schrödinger's critique of the account as well as Bohr's response, which have been misinterpreted in the literature. If adequate, the analysis may lend considerable support to the view that Bacon explicated the general terms of an experimentally minded strand of the scientific method, developed and refined by scientists in the following three centuries. (shrink)

As the theory of the atom, quantum mechanics is perhaps the most successful theory in the history of science. It enables physicists, chemists, and technicians to calculate and predict the outcome of a vast number of experiments and to create new and advanced technology based on the insight into the behavior of atomic objects. But it is also a theory that challenges our imagination. It seems to violate some fundamental principles of classical physics, principles that eventually have become a part (...) of western common sense since the rise of the modern worldview in the Renaissance. So the aim of any metaphysical interpretation of quantum mechanics is to account for these violations. (shrink)

The present article discusses shared epistemological characteristics of two distinct areas of research: the field of first-person inquiry and the field of quantum mechanics. We outline certain philosophical challenges that arise in each of the two lines of inquiry, and point towards the central similarity of their observational situation: the impossibility of disregarding the interrelatedness of the observed phenomena with the act of observation. We argue that this observational feature delineates a specific category of research that we call the non-trivial (...) domain. Unlike the trivial domain, non-trivial research cannot assume the view from nowhere on which the observed phenomena could be regarded as existing independently of the process of observation. Presenting first-person inquiry and quantum mechanics as two of its examples, we show that non-trivial research violates several fundamental observational presuppositions of the trivial domain, exemplified in the principles of classical physics. Drawing on Niels Bohr’s philosophy of quantum mechanics and the constructivist notion of enaction, we stress the constructive, participatory, and irreversible nature of observation in the non-trivial domain. We discuss the possibility of developing a non-representationalist epistemology of the non-trivial, and consider the implications of our discussion for research in the non-trivial domain, as well as for the general understanding of the scientific inquiry. (shrink)

We survey some philosophical aspects of the search for a quantum theory of gravity, emphasising how quantum gravity throws into doubt the treatment of spacetime common to the two `ingredient theories' (quantum theory and general relativity), as a 4-dimensional manifold equipped with a Lorentzian metric. After an introduction (Section 1), we briefly review the conceptual problems of the ingredient theories (Section 2) and introduce the enterprise of quantum gravity (Section 3). We then describe how three main research programmes in quantum (...) gravity treat four topics of particular importance: the scope of standard quantum theory; the nature of spacetime; spacetime diffeomorphisms, and the so-called `problem of time' (Section 4). These programmes are the old particle-physics approach, superstring theory, and canonical quantum gravity. By and large, these programmes accept most of the ingredient theories' treatment of spacetime, albeit with a metric with some type of quantum nature; but they also suggest that the treatment has fundamental limitations. This prompts the idea of going further: either by quantizing structures other than the metric, such as the topology; or by regarding such structures as phenomenological. We discuss this in Section 5. (shrink)

I argue that Immanuel Kant's critical philosophy—in particular the doctrine of transcendental idealism which grounds it—is best understood as an `epistemic' or `metaphilosophical' doctrine. As such it aims to show how one may engage in the natural sciences and in metaphysics under the restriction that certain conditions are imposed on our cognition of objects. Underlying Kant's doctrine, however, is an ontological posit, of a sort, regarding the fundamental nature of our cognition. This posit, sometimes called the `discursivity thesis', while considered (...) to be completely obvious and uncontroversial by some, has nevertheless been denied by thinkers both before and after Kant. One such thinker is Jakob Friedrich Fries, an early neo-Kantian thinker who, despite his rejection of discursivity, also advocated for a metaphilosophical understanding of critical philosophy. As I will explain, a consequence for Fries of the denial of discursivity is a radical reconceptualisation of the method of critical philosophy; whereas this method is a priori for Kant, for Fries it is in general empirical. I discuss these issues in the context of quantum theory, and I focus in particular on the views of the physicist Niels Bohr and the Neo-Friesian philosopher Grete Hermann. I argue that Bohr's understanding of quantum mechanics can be seen as a natural extension of an orthodox Kantian viewpoint in the face of the challenges posed by quantum theory, and I compare this with the extension of Friesian philosophy that is represented by Hermann's view. -/- A shorter version of this paper, focusing specifically on the views of Grete Hermann, has been published as: Cuffaro, Michael (2023). Grete Hermann, Quantum Mechanics, and the Evolution of Kantian Philosophy. In Jeanne Peijnenburg & Sander Verhaegh (eds.), Women in the History of Analytic Philosophy. Cham: Springer. pp. 114-145. (shrink)

Bas van Fraassen advocates a “Copenhagen variant” of the modal interpretation of quantum mechanics. However, he believes that the Copenhagen approach to measurement is not fully satisfactory, since it seems to rule out the possibility of providing a physical account of the observation process. This was also what John Wheeler had in mind when, in the mid-1950’s, he sponsored the “relative state” formulation proposed by his student Hugh Everett. Wheeler, who considered himself an orthodox Bohrian, tried to convince Bohr to (...) accept the improvement of the Copenhagen approach represented in his eyes by Everett’s proposal. This attempt gave rise to a lively debate, which has been only recently documented, and which provides an interesting framework for the appraisal of van Fraassen’s own programme. (shrink)

In concluding his ‘Autobiographical notes’, Albert Einstein explained that the purpose of his exposition was to ‘show the reader how the efforts of a life hang together and why they have led to expectations of a definite form’. Einstein's remarks tell of a coherence between personal ‘strivings and searchings’ and scientific activity, which has all but vanished in the midst of the current trend of social constructivism in history of science. As Nancy Nersessian recently pointed out, in the process of (...) illuminating complex relationships between scientific activity and its social context, ‘socio-historical analysis has “black-boxed” the individual scientist’. Has the pendulum swung too far? In reaction to the preceding great-man hagiographie approach to the history of science, the social constructivists have largely ‘thrown the baby out with the bathwater’; consideration of individual scientists' personal approaches to science was unnecessarily expunged with the removal of ‘genius’ as an explanatory tool. (shrink)

The ArgumentDavid Bloor often wrote that Karl Mannheim had “stopped short” in his sociology of knowledge, lacking the nerve to consider the natural sciences sociologically. While this assessment runs counter to Mannheim's own work, which responded in quite specific ways both to an encroaching “modernity” and a looming fascism, Bloor's depiction becomes clearer when considered in the light of his principal introduction to Mannheim's work — a series of essays by Robert Merton. Bloor's reading and appropriation of Mannheim emerged from (...) his background in experimental psychology and his attempts to supercede Merton's own structural-functionalist program for the sociology of knowledge. By retracing this extended trail of readings and re-readings, we may begin to understand the roots of Bloor's curious interpretation of Mannheim's sociology of knowledge, and inquire in a reflexive way about the present and future directions of science studies. (shrink)