The so-called “orthodox” interpretation of quantum physics attributed to Niels Bohr is commonly regarded as abandoning realism. I have already opposed this view elsewhere (Folse 1985) but partially in response to criticism of my position (Shimony 1985), here I propose to relate Bohr’s realism to recent contributions to the realism debate given by Hacking (1983), Cartwright (1983), and Ellis (1985). Specifically, I argue that Bohr’s complementarity viewpoint requires a causal entity realism. Furthermore, labeling Bohr an anti-realist with respect to theories is misleading because it assumes the correspondence theory of truth that Bohr holds quantum theory forces us to reject. Although there are many realist views, I take the root of realism to be the quest for knowledge about the reality producing the phenomena we experience. It is realism in this sense that Bohr defended and that makes science significant to metaphysics.
The so-called “orthodox” interpretation of quantum physics attributed to Niels Bohr is commonly regarded as abandoning realism. I have already opposed this view elsewhere (Folse 1985) but partially in response to criticism of my position (Shimony 1985), here I propose to relate Bohr’s realism to recent contributions to the realism debate given by Hacking (1983), Cartwright (1983), and Ellis (1985). Specifically, I argue that Bohr’s complementarity viewpoint requires a causal entity realism. Furthermore, labeling Bohr an anti-realist with respect to theories is misleading because it assumes the correspondence theory of truth that Bohr holds quantum theory forces us to reject. Although there are many realist views, I take the root of realism to be the quest for knowledge about the reality producing the phenomena we experience. It is realism in this sense that Bohr defended and that makes science significant to metaphysics.
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.
The surprising thing is that the most successful scientific field of the century is quantum physics, and quantum physics in its most orthodox interpretation is decidedly anti-realist. At least that is what Niels Bohr, the foremost thinker in the field, said explicitly: "an independent reality in the ordinary physical sense can neither be ascribed to the phenomena nor to the agencies of observation." Many philosophers, however, would cringe at the thought that any form of relativism may be considered sensible. Their support for realism stems in part from the belief that the alternative to realism is relativism and that relativism is incoherent. Likewise at the level of science, a view may allow the bat such striking success in dealing with certain difficult questions that the bat adopts it as his means of viewing that entire area of experience.
Now that my account of Bohr's philosophy of physics has been completed, it remains for me to give a general assessment of it. What value should we assign to Bohr's main ideas – the notions of correspondence and complementarity? How does his interpretation of quantum physics fare in comparison with some of its rivals? What should our assessment of the Bohr–Einstein debate be? I shall take up these questions in the reverse order. Einstein or Bohr? The final verdict The Bohr–Einstein debate is primarily a dispute about the philosophical foundations in terms of which the interpretation of quantum mechanics should be based: specifically it is a dispute about the intrinsic-properties theory, i.e. about the scope of a realist interpretation of quantum mechanics. Einstein wished to maintain the two realist theses, the intrinsic-properties theory and the objective-values theory, whereas Bohr wished to hold only the latter. My own philosophical leanings are in the direction of realism. To my mind the notion of a physical reality the existence and constitution of which are independent of human thought and perception is coherent and plausible: what physical objects there are, and what properties they have, is not determined by human thought or perception, or by human practical interests. I have sympathy, therefore, with Einstein's position concerning the indefinability thesis and the question of the completeness of quantum mechanics.
The objective of this article is to demonstrate how the historical debate between materialism and idealism, in the field of Philosophy, extends, in new clothes, to the field of Quantum Physics characterized by realism and anti-realism. For this, we opted for a debate, also historical, between the realism of Albert Einstein, for whom reality exists regardless of the existence of the knowing subject, and Niels Bohr, for whom we do not have access to the ultimate reality of the matter, unless conditioning it to the existence of an observer endowed with rationality, position adopted in the Interpretation of Complementarity (1927) – posture that was expanded in 1935 when Bohr assumed a “relationalist” conception, according to which the quantum state is defined by the relationship between the quantum object and the entire measuring device. This is an extremely important debate, as it further consolidates the results of nascent Quantum Mechanics, guaranteeing Bohr the leadership of the orthodoxy based on the interpretation of complementarity. Here, when dealing with Quantum Theory, we will not make any distinction between the terms Quantum Physics, Quantum Theory or Quantum Mechanics. The entire discussion will be held under the name “Quantum Theory”. Theory that tries to analyze and describe the behavior of physical systems of reduced dimensions, close to the sizes of molecules, atoms and subatomic particles. We hope that the reader will appreciate the genius of these two titans in this field of Physics when they magnificently formulate the arguments that support the object of their defenses.
I distinguish two senses in which one can take a given physical theory to be `complete'. On the first, a complete physical theory is one that, in principle, completely describes physical reality. On the second, a complete physical theory is one that provides all of the conceptual resources one needs to describe any (in general probabilistic) physical phenomenon to any level of detail one likes, in principle. I argue that while the (neo-)Everettian approach to interpreting quantum mechanics aims to show that it is complete in the first sense, the (neo-)Bohrian approach begins from an understanding of quantum mechanics as being complete in the second sense. I then discuss some of the essential differences between how classical and quantum theory describe phenomena, and the way in which the quantum description can be thought of as a ``natural generalisation'' (to use Bohr's phrase) of the classical description. Finally, I elaborate upon the two visions of physics from which one can motivate the first and the second sense of completeness, respectively: \emph{metaphysical realism}, on the one hand, and what I will call \emph{methodological realism}, on the other -- and discuss what one can say about the significance of the differences between quantum and classical description from each of these points of view. I suggest that there is a sense in which the views of (neo-)Everett and the views of (neo-)Bohr can be understood to be mutually supporting positions, from their respective perspectives, even though they are diametrically opposed.
The objective of this article is to demonstrate how the historical debate between materialism and idealism, in the field of Philosophy, extends, in new clothes, to the field of Quantum Physics characterized by realism and anti-realism. For this, we opted for a debate, also historical, between the realism of Albert Einstein, for whom reality exists regardless of the existence of the knowing subject, and Niels Bohr, for whom we do not have access to the ultimate reality of the matter, unless conditioning it to the existence of an observer endowed with rationality, position adopted in the Interpretation of Complementarity (1927) – posture that was expanded in 1935 when Bohr assumed a “relationalist” conception, according to which the quantum state is defined by the relationship between the quantum object and the entire measuring device. This is an extremely important debate, as it further consolidates the results of nascent Quantum Mechanics, guaranteeing Bohr the leadership of the orthodoxy based on the interpretation of complementarity. Here, when dealing with Quantum Theory, we will not make any distinction between the terms Quantum Physics, Quantum Theory or Quantum Mechanics. The entire discussion will be held under the name “Quantum Theory”. Theory that tries to analyze and describe the behavior of physical systems of reduced dimensions, close to the sizes of molecules, atoms and subatomic particles. We hope that the reader will appreciate the genius of these two titans in this field of Physics when they magnificently formulate the arguments that support the object of their defenses.