This book deals with the 'crisis of objectivity' and the 'crisis of realism' which overtook physics when Heisenberg and Bohr consciously rejecting the intentionality-structure of classical physics, gave physics a new form and a new philosophy. The new physics was called quantum mechanics and the new philosophy was called complimentarity. Using the method 'analysis of horizons,' the author attempts to disentangle the epistemological and ontological pesuppositions of Heisenberg's view of complementarity. A similar analysis of Bohr's view of complimentarity reveals a remarkable contrast in basic philosophy between the two founders of quantum physics. The author distinguishes various kinds of objectivity and realism and discusses critically the different aspects of the crisis that emerges in the quantum theory of measurement, the indeterminacy relations and in the statistical and causal structure of quantum mechanics. Heisenberg's formulation of the crisis is reduced to the underlying presuppositions of his thought. These presuppositions are criticised and shown to be defective. A more nuanced epistemological analysis reveals that quantum mechanics answers in a specially beautiful way to the full exigencies of the human mind and its knowledge of concrete reality.
This book deals with the 'crisis of objectivity' and the 'crisis of realism' which overtook physics when Heisenberg and Bohr consciously rejecting the intentionality-structure of classical physics, gave physics a new form and a new philosophy. The new physics was called quantum mechanics and the new philosophy was called complimentarity. Using the method 'analysis of horizons,' the author attempts to disentangle the epistemological and ontological pesuppositions of Heisenberg's view of complementarity. A similar analysis of Bohr's view of complimentarity reveals a remarkable contrast in basic philosophy between the two founders of quantum physics. The author distinguishes various kinds of objectivity and realism and discusses critically the different aspects of the crisis that emerges in the quantum theory of measurement, the indeterminacy relations and in the statistical and causal structure of quantum mechanics. Heisenberg's formulation of the crisis is reduced to the underlying presuppositions of his thought. These presuppositions are criticised and shown to be defective. A more nuanced epistemological analysis reveals that quantum mechanics answers in a specially beautiful way to the full exigencies of the human mind and its knowledge of concrete reality.
Introduction to Heelan's Quantum Mechanics and Objectivity, focused on the quantum mechanics of Heisenberg. The aim of the book is to state and analyze the 'crisis of objectivity' (or crisis of reality) in quantum physics. The method used is an analysis of the intentionality structure of quantum physics as Heisenberg conceived it to be. Through a critique, the present study seeks to arrive at a clarification of both the problem and its presuppositions and ultimately a tentative solution.
The ideas in Heisenberg's paper on quantum mechanics in 1925 mark the beginning not only of a new phase in modern physics, but also of Heisenberg's own philosophical journey. This thesis examines that journey between 1925 and the late 1950s by situating Heisenberg's philosophy of quantum mechanics in the context of his encounters with his contemporaries as well as the context of various strands of thought in the German-speaking world at the time. Heisenberg's early philosophical critique of the 'classical' viewpoint between 1925 and 1927 bears the decisive influence of Einstein's theory of relativity, more specifically, the positivism he saw as underpinning Einstein's emancipation from Newtonian physics. The positivist influence on Heisenberg's early attitude to quantum mechanics is evident in three ways: (a) his invocation of an observability principle in 1925 to justify the renunciation of the concept of the electron orbit, (b) an instrumentalist conception of understanding, which characterised Heisenberg's response to Schrodinger's demand for classical visualisation in space and time in 1926-7, and (c) the introduction of an operational definition of concepts such as position and velocity in 1927, in an attempt to replace the concepts of classical physics. But after discussions with Bohr and Einstein in 1926-7, Heisenberg soon recognised what we might term his `empiricist' viewpoint was problematic. In 1927 Heisenberg's thought undergoes a shift away from the `empiricist' viewpoint that had underpinned his early philosophy of quantum mechanics. The nature and scope of this transformation, which forms the central theme in this thesis, has, up until now, been poorly understood and often completely neglected. Through his discussions with Bohr, Heisenberg came to the realisation that despite their limitations, classical concepts were conditions for the possibility of the description of all experience. This marked the abandonment of his earlier attempt to replace classical concepts with quantum concepts. The recognition of the primacy of classical language forms the point of departure for much of Heisenberg's later thought, which brought him into contact with the attempts in the German-speaking world in the 1920s to reconstruct Kantian epistemology. By the mid-1930s, Heisenberg advocated a 'pragmatic transformation' of Kantian philosophy, in which classical concepts were held to be a priori in the sense that they remained the conditions for the possibility of experience, but were no longer held to be necessary or universal in a strict Kantian sense. After 1940 Heisenberg saw the paradoxes of quantum mechanics under the aegis of what can be termed a 'transcendental conception of language', according to which language is not a mere tool, but actively shapes, gives form, and objectifies, our 'reality'. The limits of a classical 'description' in quantum mechanics therefore came to signify for Heisenberg, the limits of 'objective reality'. While Bohr exerted perhaps the most important philosophical influence on Heisenberg, their intellectual relationship was characterised by disagreement and misunderstanding. This is most strikingly displayed in their respective views on wave-particle duality and complementarily. While after 1927 Heisenberg accepted Bohr's basic insight that our knowledge of the quantum world is mediated through classical language, he did not share Rohr's interpretation of complementarity. While Heisenberg certainly used terms such as 'complementarity' and wave-particle duality' in his writings, a close reading reveals that these terms had very different meanings for the two physicists. This is particularly evident in the contrast between Heisenberg's notion of wave-particle equivalence and Bohr's idea of complementarity. In bringing to light these divergences between Bohr and Heisenberg, this thesis lends further weight to the view - already advocated by scholars such as John Hendry and Mara Beller - that the so-called Copenhagen interpretation of quantum mechanics should not be thought of as a unified philosophical position, but actually comprises a number of different strands.
Under the assumption of the materialistic-mechanistic ontology implicit in classical physics, quantum theory as interpreted through Niels Bohr's epistemology of complementarity is not formally objective; i. e., it is not informative of the state of physical systems independent of particular phenomenal manifestations of them. However, an analysis of the notion of the “physical system”, in theory, as experienced, and as existing “in-itself”, reveals that if the older ontology is replaced, quantum mechanics through complementarity becomes formally objective, points the way toward a new ontology based on the notion of the power to structure interaction between systems, and provides new insights into the relations between theory, observation, and the natural world.
This book gives a clear and comprehensive exposition of Niels Bohr's philosophy of physics. Bohr's ideas are of major importance, for they are the source of the Copenhagen interpretation of quantum physics; yet they are obscure, and call for the sort of close analysis that this book provides. The book describes the historical background of the physics from which Bohr's ideas grew. The core of the book is a detailed analysis of Bohr's arguments for complementarity and of the interpretation which he put upon it. Special emphasis is placed throughout on the contrasting views of Einstein, and the great debate between Bohr and Einstein is thoroughly examined. The book traces the philosophical influences on Bohr, and unravels the realist and anti-realist strands in his thinking. Bohr's philosophy is critically assessed in the light of recent developments in the foundations of quantum physics (the work of Bell and others) and in philosophy (the realism-anti-realism debate) and it is revealed as being much more subtle and sophisticated than it is generally taken to be. While the book will be of interest to specialists, it is written in a style that will make it accessible to those who have no specialist knowledge of the relevant physics and philosophy.
Philosophy of science and, more specifically, philosophy of quantum physics can be but special fields of a general philosophy of knowledge; and the problems arising in these fields can be evaluated properly only when they are seen under the perspective of the whole range of human knowledge. This paper deals with problems of quantum physics and, in particular, with the problem of scientific objects in quantum physics from the epistemological point of view previously defined in the author's books, A Philosophy of Science (1940) and The Basis and Structure of Knowledge (1948). The argument of the paper, however, has not been stated before in the direct and concise manner here attempted and may therefore contain elements of novelty even for those readers who are familiar with the books just mentioned.
ABSTRACT The paper aims to bridge the history of quantum theory with its philosophical implications. The focus is not only on the scientific underpinnings of quantum mechanics (these theories emerged as ‘ad hoc’ responses to experimental anomalies) but also on the philosophical ramifications of its probabilistic nature and indeterminacy, which differ from classical realism. The paper examines Dirac's, Bell's, and modern views, focusing on how quantum mechanics (QM) challenges traditional notions of causality, objectivity, and truth while embracing epistemological and metaphysical perspectives. Debates over collapse theories and hidden variables are discussed, as well as Putnam's philosophical outlook, which includes his trenchant involvement with realism, logic, and the measurement problem. Finally, the paper proposes that QM represents a philosophical revolution that renews our understanding of reality, knowledge, and scientific explanation, rather than simply serving as a physical theory for assessing the prospects of quantum philosophy by connecting it to broader aspects such as relativity, causality, and scientific realism.