In this essay, I offer a critical evaluation of Hilary Putnam's writings on epistemology and philosophy of science, in particular his engagement with interpretative problems in quantum mechanics. I trace the development of his thinking from the late 1960s when he adopted a strong causal-realist position on issues of meaning, reference, and truth, via the "internal realist" approach of his middle-period writings, to the various forms of pragmatist, naturalized, or "commonsense" epistemology proposed in his latest books. My contention is that Putnam's retreat from a full-fledged realist outlook has been prompted in large part by his belief that it cannot possibly be reconciled with the implications of quantum mechanics for our understanding of processes and events in the subatomic domain. However, I suggest, this response should be seen as premature given the range of as-yet unresolved problems with quantum mechanics on the orthodox (Copenhagen) interpretation and also the existence of an alternative account - David Bohm's hidden-variables theory - which perfectly matches the established predictive-observational results while providing a credible realist ontology. I also examine Putnam's case for adopting a nonstandard (three-valued) "quantum logic" in relation to the thinking of other philosophers - Michael Dummett among them - who have espoused a more global or doctrinaire version of anti-realism. I conclude that Putnam's early (causal-realist) position is by no means untenable in light of the various arguments that he now takes as counting decisively against it.
In this essay, I offer a critical evaluation of Hilary Putnam's writings on epistemology and philosophy of science, in particular his engagement with interpretative problems in quantum mechanics. I trace the development of his thinking from the late 1960s when he adopted a strong causal-realist position on issues of meaning, reference, and truth, via the "internal realist" approach of his middle-period writings, to the various forms of pragmatist, naturalized, or "commonsense" epistemology proposed in his latest books. My contention is that Putnam's retreat from a full-fledged realist outlook has been prompted in large part by his belief that it cannot possibly be reconciled with the implications of quantum mechanics for our understanding of processes and events in the subatomic domain. However, I suggest, this response should be seen as premature given the range of as-yet unresolved problems with quantum mechanics on the orthodox (Copenhagen) interpretation and also the existence of an alternative account - David Bohm's hidden-variables theory - which perfectly matches the established predictive-observational results while providing a credible realist ontology. I also examine Putnam's case for adopting a nonstandard (three-valued) "quantum logic" in relation to the thinking of other philosophers - Michael Dummett among them - who have espoused a more global or doctrinaire version of anti-realism. I conclude that Putnam's early (causal-realist) position is by no means untenable in light of the various arguments that he now takes as counting decisively against it.
In this presentation, I explore the possibility of combining pluralism and scientific realism in the framework of Putnam’s pragmatic realism (Putnam, 1999; Bernstein, 2005). I illustrate my claim through the analysis of a case of Duhem-Quine underdetermination originating in the violation of Bell’s Inequalities and involving several contemporary conceptions of quantum mechanics: the instrumentalist approach called ‘no interpretation view’ (Fuchs and Peres, 2000), Bohmian Mechanics (Dürr and Teufel, 2009), the veiled reality conception (d'Espagnat, 2011) and the approach with extended probabilities (Gell-Mann and Hartle, 2012). First, I briefly expose how the violation of Bell’s Inequalities can be understood as imposing a necessary trade-off between epistemic values usually satisfied in the context of classical physics. This allows conceiving the proponents of the studied approaches as standing in “faultless” or “rational” disagreement (Gattei, 2008; Pritchard, 2009). However, while the idea of faultless disagreement becomes more and more accepted, pluralism is rarely advocated for beyond the epistemological (cognitive) human sphere. Indeed, while it is often acknowledged that several competing theories can all be reasonably endorsed (Kelly, 2005), admitting that more than one is really is usually considered as opening the door to anti-realism (about entities described by scientific theories and about truth) or to relativism. I then mobilize Putnam’s pragmatic realism to challenge this last claim, in discussing the possibility of admitting a plurality of true theories while preserving scientific realism and realism about truth. The core of Putnam’s conception is to reject sense data (or inner theater) epistemology in considering that genuine aspects of reality (and not mere mental phenomena) are met in our ordinary perception (Putnam, 1999, 2013). Putnam arrived at this conclusion after a long intellectual path initiated with the rejection of metaphysical realism and its associated understanding of truth as a unique (and transcontextual) substantive property (of correspondence to the metaphysical reality). Putnam first opposed to this type of view his internal realism in which truth becomes intimately connected to standards of rational acceptability, opening the road for conceptual pluralism (Putnam, 1981). However, this first attempt proved unsatisfying, providing no sufficient ground for realism and for discrimination between truth and verification. Putnam diagnosis is then radical: in the framework of sense data epistemology, one cannot escape the forced choice between metaphysical realism and verificationism – this is the antinomy of realism (Putnam, 1999). With pragmatic realism and the rejection of the inner theater picture, Putnam proposes an interesting alternative. It becomes possible to admit the disquotational conception of truth from Tarski while 1) escaping its deflationist interpretation without returning to metaphysical realism and 2) maintaining conceptual pluralism. According to pragmatic realism, the way a knowledge claim can be responsible to reality – can be true – is neither unique nor fixed in advance. As it will be illustrated with the discussion of the disagreement about quantum mechanics, this pragmatic realism framework permits the combined admission of conceptual pluralism and scientific realism. • Bernstein, R. J. (2005). In Y. Ben-Menahem (Ed.), Hilary Putnam (pp. 251-265): Cambridge University Press. • D'Espagnat, B. (2011). Foundations of Physics, 41(11), 1703-1716. • Dürr, D. and Teufel, S. (2009). Bohmian Mechanics: Springer Berlin Heidelberg. • Fuchs, C. A. and Peres, A. (2000). Physics Today, 53(3), 70-71. • Gattei, S. (2008). Thomas Kuhn's "Linguistic Turn" and the Legacy of Logical Empiricism: Incommensurability, Rationality and the Search for Truth: Ashgate. • Gell-Mann, M. and Hartle, J. B. (2012). Physical Review A, 85(6), 062120. • Kelly, T. (2005). In T. Szabó Gendler and J. Hawthorne
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.
This book is a critical introduction to the long-standing debate concerning the conceptual foundations of quantum mechanics and the problems it has posed for physicists and philosophers from Einstein to the present. Quantum theory has been a major infulence on postmodernism, and presents significant problems for realists. Keeping his own realist position in check, Christopher Norris subjects a wide range of key opponents and supporters of realism to a high and equal level of scrutiny. With a characteristic combination of rigour and intellectual generosity, he draws out the merits and weaknesses from opposing arguments. In a sequence of closely argued chapters, Norris examines the premises of orthodox quantum theory, as developed most influentially by Bohr and Heisenberg, and its impact on varous philosophical developments. These include the ideas developed by W.V Quine, Thomas Kuhn, Michael Dummett, Bas van Fraassen, and Hilary Puttnam. In each case, Norris argues, these thinkers have been influenced by the orthodox construal of quantum mechanics as requiring drastic revision of principles which had hitherto defined the very nature of scientific method, causal explanati and rational enquiry. Putting the case for a realist approach which adheres to well-tried scientific principles of causal reasoning and inference to the best explanation, Christopher Norris clarifies these debates to a non-specialist readership and scholars of philosophy, science studies and the philosophy of science alike. Quantum Theory and the Flight From Realism suggests that philosophical reflection can contribute to a better understanding of these crucial, current issues.
Hilary Putnam (1965, 2005) has argued that from a realist perspective, quantum mechanics stands in need of an interpretation. Ironically, this hypothesis may appear vulnerable against arguments drawing on Putnam's own work. Nancy Cartwright (2005) has urged that his 1962 essay on the meaning of theoretical terms suggests that quantum mechanics needs no interpretation and thus stands in tension with his claim of three years later. She furthermore contends that this conflict should be resolved in favour of the earlier work, as quantum mechanics, like all successful theories, does not need an interpretation. The first part of this essay deflates both of these objections. The second part addresses and evaluates Putnam's own assessments of the main interpretative options available in 1965 and 2005. Although we may disagree on some aspects, his pessimistic conclusion will come out largely unscathed, and, in fact, enhanced. I will close by briefly stating the historical relevance of this work.
On the Limits of “Undecidability”: Quantum Physics, Deconstruction, and Anti-realism Christopher Norris (bio) I Philosophers of science have responded in various ways to the conceptual and interpretative problems thrown up by quantum mechanics. These problems emerged a century ago from Planck’s researches into black-body radiation and have scarcely been resolved—rather, if anything, deepened and complicated—by the intensive debate that has surrounded them since that time.1 For some theorists, the resultant dilemmas (of observer “interference,” wave/particle dualism, quantum superposition, nonlocal causality, superluminal [faster-than-light] propagation, etc.) are such as to entail drastic revisions to our very idea of the physical world as existing and exerting its causal powers quite apart from our current best theories or investigative methods.2 For others again, quantum mechanics just is the best theory currently available, whatever the problems that it happens to create for our normal habits of logical thought or consistent reasoning on the evidence. Thus logic itself may have to be revised—right down to putative “laws of thought” such as noncontradiction and excluded middle—if these turn out to conflict with the results of quantum-mechanical theory or experiment.3 This is the view taken by Hilary Putnam in his writings on quantum logic and also by others, von Neumann among them, for whom the working rule in any such trade-off is to keep the physics as simple as possible even if the result is to complicate logic by introducing values other than those of determinate (bivalent) truth or falsehood.4 Very often it consorts with the argument that if quantum mechanics is right—at any rate on the standard Copenhagen interpretation—then we had best give up any hope of retaining a “classical” Einsteinian ontology, that is to say, a Lorentz-invariant account of space-time coordinates where the speed of light is the limiting value for assignments of position, velocity, and causal propagation.5 Hence Einstein’s famous series of debates with Niels Bohr when he devised a whole range of increasingly elaborate thought-experiments designed to prove that the quantum-mechnical description of reality had to be in some way “incomplete,” or not to have reckoned with some crucial factor that would bring it into line with logical reasoning and a causal-realist ontology. For on Einstein’s view there was simply no room in science for a theory—such as Bohr’s—that involved either the suspension of classical truth/falsehood [End Page 407] values or the idea of some “spooky action-at-a-distance” which contravened both commonsense realism and the requirements of Special Relativity.6 However it is Bohr who is generally thought to have carried the day in these debates. In which case—so it is argued—we are left with a choice between three possible “solutions.” These are (1) the hypothesis that quantum mechanics is “incomplete” or open to an alternative (“hidden-variables”) interpretation;7 (2) the adoption of an alternative (many-valued or non-bivalent) quantum logic that effectively conjures such problems away;8 or (3) the conclusion that realism may have to be abandoned in favour of some radically different ontology or worldview which counts this a price worth paying in order to conserve the predictive power of the standard quantum formalisms.9 On option (3) there is a further choice of interpretative views according to the theorist’s preferred choice between the various models (or possible-world scenarios) currently on offer. Thus the model may be one that embraces nonlocal simultaneous particle interaction, or which gives up space-time covariance (relative to the speed of light) as required by Einstein’s Special Theory. Or again it may be one that somehow envisions—strangest of all—the splitting-off of multiple coexistent but non-interacting “worlds” whenever the wave-packet collapses or whenever an act of measurement is performed upon any such quantum-system whose properties must be thought of as strictly indeterminate until that moment.10 For, according to its partisans, this theory is the most economical—i.e., involves least conflict with the standard quantum formalisms—despite its baroque proliferation of alternative worlds and its well-nigh unthinkable implications when applied...
INTRODUCTION In 1965 Hilary Putnam published the standard work on the interpretation of quantum mechanics, a piece that all philosophers of quantum mechanics of the time had to come to terms with. He laid out one-by-one in a clear non-technical way each of the available approaches to the problem and explained, again non-technically but very exactly, what is wrong with them. In his own final words Putnam took ‘the modest but essential step of becoming clear on the nature and magnitude of the difficulties’ (1965, 158). In the almost forty years since there have been a variety of advances, technical developments and new points of view. But none of these is uncontroversial. In fact each suffers from some one or another of the very difficulties that Putnam summarised. Many of the newer approaches explain why the problem is not a problem after all; a few bury the problems in technical detail; and some make heroic assumptions, often metaphysical, that cause the problems to disappear. My conclusion surveying the contemporary literature is the same as Putnam's in 1965: ‘no satisfactory interpretation of quantum mechanics exists today’ (1965, 157). The time scale is amazing. Putnam's important piece was written forty years after the first formulations and successes of quantum mechanics. I am writing forty years later, and about a theory that has transformed our technology and our way of thinking about the world. Why does this theory still have ‘no satisfactory interpretation’?