The meaning of the wave function has been a hot topic of debate since the early days of quantum mechanics. Recent years have witnessed a growing interest in this long-standing question. Is the wave function ontic, directly representing a state of reality, or epistemic, merely representing a state of knowledge, or something else? If the wave function is not ontic, then what, if any, is the underlying state of reality? If the wave function is indeed ontic, then exactly what physical (...) state does it represent? In this book, I aim to make sense of the wave function in quantum mechanics and find the ontological content of the theory. The book can be divided into three parts. The first part addresses the question of the nature of the wave function. After giving a comprehensive and critical review of the competing views of the wave function, I present a new argument for the ontic view in terms of protective measurements. In addition, I also analyze the origin of the wave function by deriving the free Schroedinger equation. The second part analyzes the ontological meaning of the wave function. I propose a new ontological interpretation of the wave function in terms of random discontinuous motion of particles, and give two main arguments supporting this interpretation. The third part investigates whether the suggested quantum ontology is complete in accounting for our definite experience and whether it needs to be revised in the relativistic domain. (shrink)

Commentary on four articles in a special issue on “theories of emotion,” comparing the theories with respect to five conceptual contrasts. The first four contrasts are essentialism versus nonessentialism, discriminative versus integrative theories, individual versus social focus, and instrumentalism versus scientific realism. Although scientific psychologists appear to have reached consensus in favor of nonessentialism and they freely use both realist and instrumentalist interpretations, there is no consensus on the other two contrasts. The final contrast explored addresses attitudes toward the use (...) of philosophy in scientific theorizing, and whether philosophy is best kept in the background or brought into the foreground. (shrink)

The late 19th century debate among German-speaking physicists about theoretical entities is often regarded as foreshadowing the scientific realism debate. This paper brings out differences between them by concentrating on the part of the earlier debate that was concerned with the conceptual consistency of the competing conceptions of matter—mainly, but not exclusively, of atomism. Philosophical antinomies of atomism were taken up by Emil Du Bois-Reymond in an influential lecture in 1872. Such challenges to the consistency of atomism had repercussions within (...) the physics community, as can be shown for the examples of Heinrich Hertz and Ludwig Boltzmann. The latter developed a series of counter-arguments, culminating in an ingenious attempt to turn the tables on the critics of atomism and prove the inconsistency of non-atomistic conceptions of nature. Underlying this controversy is a disagreement over specific goals of physical research which was considered crucially relevant to the further course of physical inquiry. It thereby exemplifies an attitude towards the realism issue that can be contrasted with a different, more neutral attitude of construing the realism issue as merely philosophical and indifferent with respect to concrete research programs in physics, which one also occasionally finds expressed in the 19th century controversy and which may be seen as the prevailing attitude of the 20th century debate. (shrink)

In An Introduction to Metaphysics Heidegger asserted that “it wasnot German idealism that collapsed; rather, the age was no longer strong enough to sustain the greatness, breadth, and originality of that spiritual world, i.e., truly to realize it”. He was at this point launchinginto one of the major themes of his later work: the “darkening of the world” in the form of the materialism and “demonism” typified by the antitheses of the USSR and the USA, a polarity of seeming opposites (...) obscuring an underlying fundamental similarity. This was the modernist faith of both cultures in the power of science to solve all of the problems that have plagued humanity for untold centuries, a faith in the power of science to tell us the absolute truth about the nature of reality. In 1955 Heidegger also characterized science and technology in “The Question Concerning Technology” as an “enframing”, a particular dominant interpretation of reality dependent on the interest of control and which conceals far more than it reveals. For one thing, “the essence of technology isin a lofty sense ambiguous. Such ambiguity points to the mystery of all revealing, i.e., of truth”. Although enframing “lets man endure,” only art as the successor of philosophy transcends techne by allowing us to see that “the essence of technologyis nothing technological”. Much earlier, in Being and Time, he gave his first sustained account of science as the interpretationof reality driven by technological interests, and spoke of Being as the “transcendens” lying beyond “every possible character which an entity can possess” [p. 38]. It remains debatable whether this characterization of Being survived into Heidegger's later period, but despite his nostalgia for the spirituality of the early nineteenth century, the role of Beingin these earlier works might best be explained as some kind of realism. (shrink)

This article argues in favour of an inferential role for fictions in scientific modelling. The argument proceeds by means of a detailed case study, namely models of the internal structure of stars in stellar astrophysics. The main assumptions in such models are described, and it is argued that they are best understood as useful fictions. The role that conditionals play in these models is explained, and it is argued that fictional assumptions play an important role as either background or antecedent (...) conditions. I then expand on the argument for the compatibility of fictions and scientific realism. I argue that realism and antirealism plausibly offer correspondingly different accounts of the semantics of these fictional conditionals. (shrink)

It is argued that a realistic interpretation of quantum mechanics is possible and useful. Current interpretations, from “Copenhagen” to “many worlds” are critically revisited. The difficulties for intuitive models of quantum physics are pointed out and possible solutions proposed. In particular the existence of discrete states, the quantum jumps, the alleged lack of objective properties, measurement theory, the probabilistic character of quantum physics, the wave–particle duality and the Bell inequalities are analyzed. The sketch of a realistic picture of the quantum (...) world is presented. It rests upon the assumption that quantum mechanics is a stochastic theory whose randomness derives from the existence of vacuum fields. They correspond to the vacuum fluctuations of quantum field theory, but taken as real rather than virtual. (shrink)

I discuss changes of perspective of four kinds in science and about science. Section 2 defends a perspectival nonrealism—something akin to Giere’s perspectival realism but not a realism—against the idea of complete, “Copernican” objectivity. Section 3 contends that there is an inverse relationship between epistemological conservatism and scientific progress. Section 4 casts doubt on strong forms of scientific realism by taking a long-term historical perspective that includes future history. Section 5 defends a partial reversal in the status of so-called context (...) of discovery and context of justification. Section 6 addresses the question of how we can have scientific progress without scientific realism—how progress is possible without the accumulation of representational truth. The overall result is a pragmatic instrumentalist perspective on the sciences and how to study them philosophically, one that contains a kernel of realism—instrumental realism. (shrink)

In her recent book Lindley Darden has endeavored to reclaim for philosophy an active role in the elaboration of good science. She has done this, not by holding up some set of rational standards derived from outside of scientific practice, but rather by delving into the history of science and coming out with a set of scientific strategies. Unconcerned about whether any particular strategy wasin fact employed in a given historical case her project depends upon two claims, first that these (...) strategiescould have been successfully deployed in the particular cases from which they were construed, and second and more importantly, that these strategies can be generalized beyond any particular context and be put to future use. It will be argued that Darden''s conception of the possible context independence of scientific strategies is based upon an overly cognitivist misconstrual. An alternative account of the relationship of context dependent and context independent aspects of scientific theory formation will be offered as well as its implications for philosophy. (shrink)

This article presents and discusses an innovative pedagogical device designed for training pre-service teachers on the nature of science. We endorse an approach according to which aspects of the nature of science should be explicitly discussed in order to be understood by learners. We identified quantum physics, and more precisely the principles of uncertainty and complementarity, as a rich topic suitable for such a discussion. Our training device consists in preparing and staging a new type of theater, the “scientific experimental (...) theater,” based both on the characteristics of Brecht’s theater and Kelly’ cyclic theory of learning. This device was implemented with a group of eight pre-service teachers. According to our observations, the approach favors their involvement and provides them with a frame for expressing their doubts and confronting their points of view. By analyzing their discussion, we identified several aspects of the nature of science that the pre-service teachers raised spontaneously: subjectivity, the social and cultural embeddedness of science, the construction and status of models, and the role of questioning in the development of science. The implemented device therefore appears as an interesting means for stimulating a rich discussion on the nature of science. This study opens new avenues for teachers’ and students’ training devices aimed at developing a critical and reflective stance on science. (shrink)

The view that takes laws of nature to be essentially nothing more than descriptions of facts is still rather popular. The present article, on the contrary, defends the claim that the only real motivation for defending a descriptive view of laws—the quest for ontological parsimony—entails too high a price to pay in philosophical terms. It is argued that nomic primitivism, namely the alternative option that takes laws to be primitive fundamental entities in our ontology, is decisively more appealing, since it (...) is the crucial role assigned to laws that makes a scientific theory of natural phenomena a system rather than a list. Finally, the implications that nomic primitivism might have for the issue of the status of the wave function in that particular formulation of quantum mechanics known as Bohmian mechanics are considered. (shrink)

Gerald Holton has famously described Einstein’s career as a philosophical “pilgrimage”. Starting on “the historic ground” of Machian positivism and phenomenalism, following the completion of general relativity in late 1915, Einstein’s philosophy endured (a) a speculative turn: physical theorizing appears as ultimately a “pure mathematical construction” guided by faith in the simplicity of nature and (b) a realistic turn: science is “nothing more than a refinement ”of the everyday belief in the existence of mind-independent physical reality. Nevertheless, Einstein’s mathematical constructivism (...) that supports his unified field theory program appears to be, at first sight, hardly compatible with the common sense realism with which he countered quantum theory. Thus, literature on Einstein’s philosophy of science has often struggled in finding the thread between ostensibly conflicting philosophical pronouncements. This paper supports the claim that Einstein’s dialog with Émile Meyerson from the mid 1920s till the early 1930s might be a neglected source to solve this riddle. According to Einstein, Meyerson shared (a) his belief in the independent existence of an external world and (b) his conviction that the latter can be grasped only by speculative means. Einstein could present his search for a unified field theory as a metaphysical-realistic program opposed to the positivistic-operationalist spirit of quantum mechanics. (shrink)

The debate over scientific realism, simply put, is a debate over what we can and should believe about reality once we've critically assessed all the available arguments and empirical evidence. Thinking earnestly about the merits of scientific realism as a philosophical thesis requires navigating contentious historiographical issues, being familiar with the technical details of various scientific theories, and addressing disparate philosophical problems spanning aesthetics, metaphysics, epistemology, and beyond. This issue of Spontaneous Generations: A Journal for the History and Philosophy of (...) Science aims to make participating in the scientific realism debate easier for both newcomers and veterans, collecting over twenty invited and peer-reviewed papers under the title "The Future of the Scientific Realism Debate: Contemporary Issues Concerning Scientific Realism.". (shrink)

Schrödinger averred that entanglement is the characteristic trait of quantum mechanics. The first part of this paper is simultaneously an exploration of Schrödinger’s claim and an investigation into the distinction between mere entanglement and genuine quantum entanglement. The typical discussion of these matters in the philosophical literature neglects the structure of the algebra of observables, implicitly assuming a tensor product structure of the simple Type I factor algebras used in ordinary Quantum Mechanics . This limitation is overcome by adopting the (...) algebraic approach to quantum physics, which allows a uniform treatment of ordinary QM, relativistic quantum field theory, and quantum statistical mechanics. The algebraic apparatus helps to distinguish several different criteria of quantum entanglement and to prove results about the relation of quantum entanglement to two additional ways of characterizing the classical versus quantum divide, viz. abelian versus non-abelian algebras of observables, and the ability versus inability to interrogate the system without disturbing it. Schrödinger’s claim is reassessed in the light of this discussion. The second part of the paper deals with the relativity-to-ambiguity threat: the entanglement of a state on a system algebra is entanglement of the state relative to a decomposition of the system algebra into subsystem algebras; a state may be entangled with respect to one decomposition but not another; hence, unless there is some principled way to choose a decomposition, entanglement is a radically ambiguous notion. The problem is illustrated in terms a Realist versus Pragmatist debate, the former claiming that the decomposition must correspond to real as opposed to virtual subsystems, while the latter claims that the real versus virtual distinction is bogus and that practical considerations can steer the choice of decomposition. This debate is applied to the fraught problem of measuring entanglement for indistinguishable particles. The paper ends with some remarks about claims in the philosophical literature that entanglement undermines the separability or independence of subsystems while promoting holism. (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)

The ArgumentIn this paper I argue that Kuhn's and Hanson's notion of incommensurable paradigms is rooted in the rhetoric of finality of the Copenhagen dogma — the orthodox philosophical interpretation of quantum physics. I also argue that arguments for holism of a paradigm, on which the notion of the impossibility of its gradual modification is based, misinterpret the Duhem-Quine thesis. The history of science (Copernican, Chemical, and Quantum Revolutions) demonstrates fruitful selective appropriation of ideas from seemingly “incommensurable” paradigms (rather than (...) the impossibility of communication between their representatives). I argue in conclusion that such openness underlies scientific creativity, and that dialogue between different alternatives is indispensable for the growth of knowledge. (shrink)

Classical physics and quantum physics suggest two meta-physical types of reality: the classical notion of a objectively definite reality with properties "all the way down," and the quantum notion of an objectively indefinite type of reality. The problem of interpreting quantum mechanics (QM) is essentially the problem of making sense out of an objectively indefinite reality. These two types of reality can be respectively associated with the two mathematical concepts of subsets and quotient sets (or partitions) which are category-theoretically dual (...) to one another and which are developed in two mathematical logics, the usual Boolean logic of subsets and the more recent logic of partitions. Our sense-making strategy is "follow the math" by showing how the logic and mathematics of set partitions can be transported in a natural way to Hilbert spaces where it yields the mathematical machinery of QM--which shows that the mathematical framework of QM is a type of logical system over ℂ. And then we show how the machinery of QM can be transported the other way down to the set-like vector spaces over ℤ₂ showing how the classical logical finite probability calculus (in a "non-commutative" version) is a type of "quantum mechanics" over ℤ₂, i.e., over sets. In this way, we try to make sense out of objective indefiniteness and thus to interpret quantum mechanics. (shrink)

Neo-positivism is dead. Let that imperfect designation stand for the project that dominated and defined the philosophy of science, especially in its Anglophone form, during the fifty or so years following the end of the Second World War. While its critics were many,1 its death was slow, and some think still to find a pulse.2 But die it did in the cul-de-sac into which it was led by its own faulty compass.

This is a review of those key thought experiments in physics from the late 19th century onward that seem to have played a particular role in the process of the discovery or advancement of theory. Among others the paper discusses Maxwell's demon, several of Einstein's thought experiments in relativity, Heisenberg's microscope, the Einstein-Schrödinger cat, and the EPR thought experiment.

There are two broad opposing classes of attitudes to reality with corresponding attitudes to knowledge. I argue that these attitudes can be compatible, and that quantum theory requires us to adopt both of them.

In 1935 Einstein, Podolsky, and Rosen (EPR) published an important paper in which they claimed that the whole formalism of quantum mechanics together with what they called ``Reality Criterion'' imply that quantum mechanics cannot be complete. That is, there must exist some elements of reality that are not described by quantum mechanics. There must be, they concluded, a more complete description of physical reality behind quantum mechanics. There must be a state, a hidden variable, characterizing the state of affairs in (...) the world in more details than the quantum mechanical state, something that also reflects the missing elements of reality. Under some further but quite plausible assumptions, this conclusion implies that in some spin-correlation experiments the measured quantum mechanical probabilities should satisfy particular inequalities (Bell-type inequalities). The paradox consists in the fact that quantum probabilities do not satisfy these inequalities. And this paradoxical fact has been confirmed by several laboratory experiments in the last three decades. The problem is still open and hotly debated among both physicists and philosophers. It has motivated a wide range of research from the most fundamental quantum mechanical experiments through foundations of probability theory to the theory of stochastic causality as well as the metaphysics of free will. (shrink)

From classical mechanics to quantum field theory, the physical facts at one point in space are held to be independent of those at other points in space. I propose that we can usefully challenge this orthodoxy in order to explain otherwise puzzling correlations at both cosmological and microscopic scales.