According to a widespread view, the Bell theorem establishes the untenability of so-called ‘local realism’. On the basis of this view, recent proposals by Leggett, Zeilinger and others have been developed according to which it can be proved that even some non-local realistic theories have to be ruled out. As a consequence, within this view the Bell theorem allows one to establish that no reasonable form of realism, be it local or non-local, can be (...) made compatible with the (experimentally tested) predictions of quantum mechanics. In the present paper it is argued that the Bell theorem has demonstrably nothing to do with the ‘realism’ as defined by these authors and that, as a consequence, their conclusions about the foundational significance of the Bell theorem are unjustified. (shrink)

Emilio Santos has argued (Santos, Studies in History and Philosophy of Physics http: //arxiv-org/abs/quant-ph/0410193) that to date, no experiment has provided a loophole-free refutation of Bell’s inequalities. He believes that this provides strong evidence for the principle of local realism, and argues that we should reject this principle only if we have extremely strong evidence. However, recent work by Malley and Fine (Non-commuting observables and local realism, http: //arxiv-org/abs/quant-ph/0505016) appears to suggest that experiments refuting Bell’s inequalities (...) could at most confirm that quantum mechanical quantities do not commute. They also suggest that experiments performed on a single system could refute local realism. In this paper, we develop a connection between the work of Malley and Fine and an argument by Bub from some years ago [Bub, The Interpretation of Quantum Mechanics, Chapter VI(Reidel, Dodrecht,1974)]. We also argue that the appearance of conflict between Santos on the one hand and Malley and Fine on the other is a result of differences in the way they understand local realism. (shrink)

Based on the new general framework for the probabilistic description of experiments, introduced in [E.R. Loubenets, Research Report No 8, MaPhySto, University of Aarhus, Denmark (2003); Proceedings Conference “Quantum Theory, Reconsideration of Foundations”, Ser. Math. Modeling, Vol. 10 (University Press, Vaxjo, 2004), pp. 365–385], we analyze in mathematical terms the link between the validity of Bell-type inequalities under joint experiments upon a system of any type and the physical concept of “local realism”. We prove that the violation of (...) Bell-type inequalities in the quantum case has no connection with the violation of “local realism”. In a general setting, we formulate in mathematical terms the condition on “local realism” under a joint experiment and consider examples of quantum “locally realistic” joint experiments. We, in particular, show that quantum joint experiments of the Alice/Bob type are “locally realistic”. For an arbitrary bipartite quantum state, we derive quantum analogs of the original Bell inequality. In view of our results, we argue that the violation of Bell-type inequalities in the quantum case cannot be a valid argument in the discussion on locality or non-locality of quantum interactions. (shrink)

Specker contradiction, I prove that ‘local realistic’ theories predict nontrivial violations of the quantum mechanical EPR-type perfect anticorrelations. The proof invokes the same stochastic local realism conditions used in Bell arguments. For a class of theories called ‘orthodox spin theories’, the perfect anticorrelations used in the proof emerge from rotational symmetry. Therefore, an orthodox spin theorist must abandon either the spirit of relativity, as encoded by local realism, or the letter of relativity, which demands rotational (...) invariance. (shrink)

This paper presents a realistic, stochastic, and local model that reproduces nonrelativistic quantum mechanics results without using its mathematical formulation. The proposed model only uses integer-valued quantities and operations on probabilities, in particular assuming a discrete spacetime under the form of a Euclidean lattice. Individual particle trajectories are described as random walks. Transition probabilities are simple functions of a few quantities that are either randomly associated to the particles during their preparation, or stored in the lattice nodes they visit (...) during the walk. QM predictions are retrieved as probability distributions of similarly-prepared ensembles of particles. The scenarios considered to assess the model comprise of free particle, constant external force, harmonic oscillator, particle in a box, the Delta potential, particle on a ring, particle on a sphere and include quantization of energy levels and angular momentum, as well as momentum entanglement. (shrink)

The reality of physical properties is divided into two types: “relatively” and “absolutely” real. Concerning the reality of spatial observables, it is proposed to drop the concept of an absolute reality of spatial observables. The resulting relative reality then isnot the observer-dependent reality of the standard interpretation of quantum mechanics, but rather the reference frame-dependent reality implied by the principle of relativity. Within the frame of this relative reality, it is then shown that a local explanation for the existence (...) of EPR correlations can be found when two-valued discrete spatially directed observables (like the spin-1/2 components of electrons, or the polarization states of photons) are assumed. The new explanation is formally analogous to the standard explanation of classical correlations at a distance. Sufficient assumptions to obtain this result are the isotropy of space and the existence of two-valued discrete spatially directed observables. Thus, the possibility to find a both local and realistic explanation of correlations at a distance is extended to quantum variables violating Bell's inequality. (shrink)

We present a pragmatic analysis of the different meanings assigned to the term “local realism” in the context of the empirical violations of Bell-type inequalities since its inception in the late 1970s. We point out that most of them are inappropriate and arise from a deeply ingrained prejudice that originated in the celebrated 1935 paper by Einstein-Podolski-Rosen. We highlight the correct connotation that arises once we discard unnecessary metaphysics.

A method is given to determine whether or not the distribution functions describing the two spin measurements in the spin-s Einstein-Podolsky-Rosen experiment are compatible with the existence of distributions describing three spin measurements (not all of which can actually be performed). When applied to the spin-1/2 case the method gives the results of Wigner, or of Clauser, Holt, Horne, and Shimony, depending on whether or not the two-spin distributions are assumed to have the forms given by the quantum theory. Generalizations (...) of the conditions of Wigner or of Clauser et al. to the spin-1 case are explicitly calculated. The spin-3/2 case is examined in some simple geometries to show that an apparently monotonic trend toward local realism as s increases from1/2 to1 is, in fact, violated when s increases from1 to3/2. The analysis is based on a novel representation of the modulus squared of a rotation matrix element. The structure of that matrix element responsible for the restoration of local realism in the classical (large s) limit is identified, but a rigorous treatment of the classical limit is not attempted. The higher-spin results are significantly stronger than those given by Mermin's spin-s Bell inequality. (shrink)

This paper argues that realism issue in the social sciences is not one that can be decided by general philosophical arguments that evaluate entire domains at once. The realism issue is instead many different empirical issues. To defend these claims, I sort issues that are often run together, explicate and criticize several standard realist and antirealist arguments about the social sciences, and use the example of the productive/nonproductive distinction to illustrate the approach to realism questions that I (...) favor. (shrink)

We illustrate an explicit counterexample to Bell's theorem by constructing a pair of spin variables within S^3 that exactly reproduces the EPR-Bohm correlation in a manifestly local-realistic manner.

According to a wrong interpretation of the Bell theorem, it has been repeatedly claimed in recent times that we are forced by experiments to drop any possible form of realism in the foundations of quantum mechanics. In this paper I defend the simple thesis according to which the above claim cannot be consistently supported: the Bell theorem does not concern realism, and realism per se cannot be refuted in itself by any quantum experiment. As a consequence, (...) class='Hi'>realism in quantum mechanics is not something that can be simply explained away once and for all on the basis of experiments, but rather something that must be conceptually characterized and discussed in terms of its foundational virtues and vices. To assess it, we cannot rely on experimentation but rather on philosophical discussion: realism is not a phlogiston-like notion, despite the efforts of the contemporary quantum orthodoxy to conceive it in Russellian terms as the relics of a bygone age. (shrink)

According to a wrong interpretation of the Bell theorem, it has been repeatedly claimed in recent times that we are forced by experiments to drop any possible form of realism in the foundations of quantum mechanics. In this paper I defend the simple thesis according to which the above claim cannot be consistently supported: the Bell theorem does not concern realism, and realism per se cannot be refuted in itself by any quantum experiment. As a consequence, (...) class='Hi'>realism in quantum mechanics is not something that can be simply explained away once and for all on the basis of experiments, but rather something that must be conceptually characterized and discussed in terms of its foundational virtues and vices. To assess it, we cannot rely on experimentation but rather on philosophical discussion: realism is not a phlogiston-like notion, despite the efforts of the contemporary quantum orthodoxy to conceive it in Russellian terms as the relics of a bygone age. (shrink)

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 – 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. (shrink)

It is argued that the long standing failure to show an uncontroversial, loophole-free, empirical violation of a Bell inequality should be interpreted as a support to local realism. After defining realism and locality, this as relativistic causality, the performed experimental tests of Bell’s inequalities are commented. It is pointed out that, without any essential modification of quantum mechanics, the theory might be compatible with local realism.

A pair of spin-j particles, prepared in a singlet state, move away from each other and are examined by two distant observers. If the latter are able to discriminate between the2j+1 values of a component ofJ, there are pairs of observables whose correlation strongly violates Bell's inequality, for arbitrarily large j. However, if neighboring values are lumped together because of limited instrumental resolution, the observable correlations tend to those predicted by classical mechanics.

Many beautiful experiments have been addressed to test standard quantum mechanics against local realistic models. Even if a strong evidence favouring standard quantum mechanics is emerged, a conclusive experiment is still lacking, because of low detection efficiencies. Recently, experiments based on pseudoscalar mesons have been proposed as a way for obtaining a conclusive experiment. In this paper, we investigate if this result can effectively be obtained. Our conclusions, based on a careful analysis of the proposed set ups, are that (...) this will not be possible due to intrinsic limitations of these kind of experiments. (shrink)

A novel and versatile polarization-entanglement scheme is adopted to investigate the violation of the EPR local realism for a non-maximally entangled two-photon system according to the recent nonlocality proof by Lucien Hardy. In this context the adoption of a sophisticated detection method allows direct determination of any element of physical reality (viz., determined with probability equal to unity in the words of Einstein, Podolsky and Rosen) for the pair system within complete measurements that are largely insensitive to the (...) detector quantum-efficiencies and noise. (shrink)

A novel and versatile polarization-entanglement scheme is adopted to investigate the violation of the EPR local realism for a non-maximally entangled two-photon system according to the recent “nonlocality proof” by Lucien Hardy. In this context the adoption of a sophisticated detection method allows direct determination of any “element of physical reality” (viz., determined “with probability equal to unity” in the words of Einstein, Podolsky and Rosen) for the pair system within complete measurements that are largely insensitive to the (...) detector quantum-efficiencies and noise. (shrink)

Here is a simple, clear, useful proof that quantum mechanics contradicts Einstein, Podolsky, and Rosen's local realistic assumptions. It is a variant of the powerful argument first worked out by Daniel Mordechai Greenberger, Michael A. Horne, and Anton Zeilinger. This version uses the eigenstates of two orthogonal spin components for three spin-1/2 particles. No operator or matrix algebra is necessary. A novel discussion of the background and history serves to introduce this proof and to place it in the context (...) of Danny's work. (shrink)

Since he proved his theorem in 1982, Fine has been challenging the traditional interpretation of the experimental violation of the Bell Inequalities. A natural interpretation of Fine's theorem is that it provides us with an alternative set of assumptions on which to place blame for the failure of the BI, and opens to a new interpretation of the violation of the BI. Fine has a stronger interpretation for his theorem. He claims that his result undermines the traditional interpretation in terms (...) of local realism. The aim of this paper is to understand and to assess Fine's claim. We distinguish three different strategies that Fine uses in order to support his view. We show that none of these strategies is successful. Fine fails to prove that local realism is not at stake in the violation of the BI by quantum phenomena. (shrink)

We show that the divergence between the predictions of quantum optics and the local realist theory known as stochastic optics, for the extended type of photon-coincidence experiment described recently by de Caro, is of the same order of magnitude as for Aspect-type experiments. This means that, in such new experiments, as in those so far performed, counting statistics will have to be greatly improved before a discrimination between the two theories becomes possible.We also show that the outstanding difference between (...) the two theories is that, while stochastic optics uses a genuine, that is, positive, detection probability, the corresponding quantum formalism leads to a pseudoprobability. Nevertheless, there is a striking parallel, in that both theories recognize the phenomenon known as enhancement, and both describe it as having its origin in a mixing of the signal field with the zero-point field by a polarizing device. (shrink)

A new realislic local model of light propagation and detection is described. The authors propose a novel stochastic model of low-intensity photon detection in which background noise is added to a part of the photon prior to absorption. In this model, in agreement with Planck, there is no quantization of the propagating field. The model has some similarities to theories advanced by E. Santos and T. Marshall in the last decade, but also has substantial deviations from these. A mechanism, (...) conserving energy and momentum, is proposed by which a sudden collapse of the wave-packet is avoided. The experimental Bell inequality violation of Aspect. Grangier and Roger [Phys. Rev. Lett.47, 460 (1981)]is discussed. The authors have carried out a computer simulation of a radio frequency (RF) analogue of the Einstein-Podolsky-Rosen thought experiment to illustrate how the manipulation of certain factors, especially signal to noise ratio, detector threshold and characteristics of the noise, enables the same Bell inequality to be either satisfied or violated by a realistic local model. Building on arguments by Santos. [Phys. Rev. A46. 3646 (1992)],the appropriateness of this Bell lest is discussed. Neither the authors' stochastic-optical model, nor their RF analogue, involves an enhancement assumption of the type defined by Clauser and Horne [Phys. Rev. D10, 526 (1974)]. (shrink)

This paper argues that realism issue in the social sciences is not one that can be decided by general philosophical arguments that evaluate entire domains at once. The realism issue is instead many different empirical issues. To defend these claims, I sort issues that are often run together, explicate and criticize several standard realist and antirealist arguments about the social sciences, and use the example of the productive/nonproductive distinction to illustrate the approach to realism questions that I (...) favor. (shrink)

Scientific realism and anti-realism are most frequently discussed as global theses: theses that apply equally well across the board to all the various sciences. Against this status quo I defend the localist alternative, a methodological stance on scientific realism that approaches debates on realism at the level of individual sciences, rather than at science itself. After identifying the localist view, I provide a number of arguments in its defense, drawing on the diversity and disunity found in (...) the sciences, as well as problems with other approaches (such as basing realism debates on the aim of science). I also show how the view is already at work, explicitly or implicitly, in the work of several philosophers of science. After meeting the objections that localism collapses either into globalism or hyperlocalism, I conclude by sketching what sorts of impacts localism can have in the philosophy of science. (shrink)

In order to examine the fit between realism and science, one needs to address two issues: the unit of science question (realism about which parts of science?) and the contents of realism question (which realism about science?). Answering these questions is a matter of conceptual and empirical inquiry by way local case studies. Instead of the more ordinary abstract and global scientific realism, what we get is a doubly local scientific realism based (...) on a bottom-up strategy. Representative formulations of the former kind are in terms of the truth and reality of the posits of current science, in terms of warranted belief, in terms of mind-independent unobservable entities. Using illustrations mainly from the social sciences, doubly local scientific realism denies the global applicability of such formulations and seeks to make adjustments in their elements in response to information about local units of science: It is sufficient for a realist to give the existence of an entity (and the truth of a theory) a chance, while in some areas we may be in s position to make justified claims about actual existence (and truth). Logical inquiry-independent existence is sufficient for the social and human sciences, while mind-independence will be fine for many other domains. It should not be insisted that the theoretical posits of realist science be strict unobservables in all areas: most theoretical posits of the social sciences are idealized commonsensibles, such as elements in folk psychology. Unsurprisingly, this sort of local strategy will create space for realism that is able to accommodate larger areas of science without sacrificing traditional realist intuitions. (shrink)

This article elaborates local selective realism in view of the shifting from classical to quantum electrodynamics. After some introductory remarks, we critically address what we call global selective realism, hence setting forth the background for outlining local selective realism. When examining the transition from classical to quantum electrodynamics, we evaluate both continuities and discontinuities in observational features, mathematical structures, and ontological presuppositions. Our argument leads us to criticise the narrow understanding of limiting-case strategies, and to (...) reject the claim that we need a fully coherent theoretical framework to account for the transition from one theory to its successor in the case of electrodynamics. We close with a few remarks on the scope of local selective realism. (shrink)

Two types of contextual theories are distinguished and shown to be related. For theories of each type a criterion of locality is formulated which is weaker than the classical requirement of separability at spacelike intervals. The relations between the concepts of locality, realism, and ontic chance are discussed.

This book concentrates on research done during the last twenty years on the philosophy of quantum mechanics. In particular, the author focuses on three major issues: whether quantum mechanics is an incomplete theory, whether it is non-local, and whether it can be interpreted realistically. Much of the book is concerned with distinguishing various senses in which these questions can be taken, and assessing the bewildering variety of answers philosophers and physicists have given up to now. The book is self-contained (...) in that it presents the necessary parts of the mathematical formalism of quantum mechanics and also covers other interpretative topics, such as the problem of measurement and the uncertainty relations. A considerable portion of the book is based on original arguments presented by the author in lectures and research papers over the past ten years. However, this material is integrated with a broad coverage of most of the recent research in the field, so as to provide a balanced introduction to the whole subject. (shrink)

We examine recent work in cognitive neuroscience that investigates brain networks. Brain networks are characterized by the ways in which brain regions are functionally and anatomically connected to one another. Cognitive neuroscientists use various noninvasive techniques (e.g., fMRI) to investigate these networks. They represent them formally as graphs. And they use various graph theoretic techniques to analyze them further. We distinguish between knowledge of the graph theoretic structure of such networks (structural knowledge) and knowledge of what instantiates that structure (nonstructural (...) knowledge). And we argue that this work provides structural knowledge of brain networks. We explore the significance of this conclusion for the scientific realism debate. We argue that our conclusion should not be understood as an instance of a global structural realist claim regarding the structure of the unobservable part of the world, but instead, as a local structural realist attitude towards brain networks in particular. And we argue that various local approaches to the realism debate, i.e., approaches that restrict realist commitments to particular theories and/or entities, are problematic insofar as they don't allow for the possibility of such a local structural realist attitude. (shrink)

According to a recent paper by Tim Maudlin, Bell’s theorem has nothing to tell us about realism or the descriptive completeness of quantum mechanics. What it shows is that quantum mechanics is non-local, no more and no less. What I intend to do in this paper is to challenge Maudlin’s assertion about the import of Bell’s proof. There is much that I agree with in the paper; in particular, it does us the valuable service of demonstrating that Einstein’s (...) objections to quantum mechanics have nothing to do with its indeterminism. But I do think that Maudlin’s conclusion is overly cut-and-dried. Quantum mechanics is far from a unified edifice, and what Bell’s theorem shows depends on what version of quantum mechanics you look at. In particular, I’ll try to make the case that there’s an interesting, if ultimately uncompelling anti-realist construal of the import of Bell’s theorem. And I also want to suggest that locality isn’t quite as decisively defeated as Maudlin claims. (shrink)

We reconsider the consequences of the observed violations of Bell's inequalities. Two common responses to these violations are (i) the rejection of realism and the retention of locality and (ii) the rejection of locality and the retention of realism. Here we critique response (i). We argue that locality contains an implicit form of realism, since in a worldview that embraces locality, spacetime, with its usual, fixed topology, has properties independent of measurement. Hence we argue that response (i) (...) is incomplete, in that its rejection of realism is only partial. (shrink)

The paper has two aims: (1) it sets out to show that it is well motivated to seek for an account of quantum non-locality in the framework of ontic structural realism (OSR), which integrates the notions of holism and non-separability that have been employed since the 1980s to achieve such an account. However, recent research shows that OSR on its own cannot provide such an account. Against this background, the paper argues that by applying OSR to the primitive ontology (...) theories of quantum physics, one can accomplish that task. In particular, Bohmian mechanics offers the best prospect for doing so. (2) In general, the paper seeks to bring OSR and the primitive ontology theories of quantum physics together: on the one hand, in order to be applicable to quantum mechanics, OSR has to consider what the quantum ontology of matter distributed in space-time is. On the other hand, as regards the primitive ontology theories, OSR provides the conceptual tools for these theories to answer the question of what the ontological status of the wave-function is. (shrink)

We examine the prevalent use of the phrase “local realism” in the context of Bell’s Theorem and associated experiments, with a focus on the question: what exactly is the ‘realism’ in ‘local realism’ supposed to mean? Carefully surveying several possible meanings, we argue that all of them are flawed in one way or another as attempts to point out a second premise (in addition to locality) on which the Bell inequalities rest, and (hence) which might (...) be rejected in the face of empirical data violating the inequalities. We thus suggest that the phrase ‘local realism’ should be banned from future discussions of these issues, and urge physicists to revisit the foundational questions behind Bell’s Theorem. (shrink)

When explaining the causes of structural variations in local governance reform, regional studies scholars face a trilemma: how to avoid voluntarism that over-inflates individuals’ power to ‘heroically’ reorganize local governance regimes; how to avoid determinism that denies the prowess of local actors in the face of institutional constraints; and how to avoid constructivism that denies the separate existence of both individual actions and local institutions. The question they must answer is: if individuals are embedded in institutions (...) that define their interests and shape their cognitions, how can they ever be able to change institutions? Critical realism suggests a suitable answer to this question by seeing institutional dynamics as consisting of structures, institutions, and actions, each with a distinct existence but nevertheless irreducible to each other. The practical value of this ontology – which avoids voluntarism, determinism and constructivism – is illustrated by an English devolution case study. (shrink)

The violation of Bell inequalities by quantum physical experiments disproves all relativistic micro causal, classically real models, short Local Realistic Models (LRM). Non-locality, the infamous “spooky interaction at a distance” (A. Einstein), is already sufficiently ‘unreal’ to motivate modifying the “realistic” in “local realistic”. This has led to many worlds and finally many minds interpretations. We introduce a simple many world model that resolves the Einstein Podolsky Rosen paradox. The model starts out as a classical LRM, thus clarifying (...) that the many worlds concept alone does not imply quantum physics. Some of the desired ‘non-locality’, e.g. anti-correlation at equal measurement angles, is already present, but Bell’s inequality can of course not be violated. A single and natural step turns this LRM into a quantum model predicting the correct probabilities. Intriguingly, the crucial step does obviously not modify locality but instead reality: What before could have still been a direct realism turns into modal realism. This supports the trend away from the focus on non-locality in quantum mechanics towards a mature structural realism that preserves micro causality. (shrink)

Eating local food has become a mainstream proxy for virtue and a reliable model of sustainable dieting. It suffers, nonetheless, from genuine criticisms and limitations. In this paper, we suggest theoretical amendments to reorient the local food movement and turn eating local into a robust concept—comprehensive, coherent, and inclusive, affording a firm grip over structural aspects of the food chain. We develop our argument in three parts. The first contends that ‘local’ can be said of lots (...) of entities (e.g. whole or multi-ingredient foods, recipes, menus) and that its meaning varies depending on which entities are under consideration. The second examines three dimensions of being local: the distance from the place of production; the geographical origins; the social links to consumers and producers. The third presents our robust conception of eating local, grounded on a more realistic model that accommodates for heterogeneous and complex actors. (shrink)

The authors of Austere Realism describe and defend a provocative ontological-cum-semantic position, asserting that the right ontology is minimal or austere, in that it excludes numerous common-sense posits, and that statements employing such posits are nonetheless true, when truth is understood to be semantic correctness under contextually operative semantic standards. Terence Horgan and Matjaz [hacek over z] Potrc [hacek over c] argue that austere realism emerges naturally from consideration of the deep problems within the naive common-sense approach to (...) truth and ontology. They offer an account of truth that confronts these deep internal problems and is independently plausible: contextual semantics, which asserts that truth is semantically correct affirmability. Under contextual semantics, much ordinary and scientific thought and discourse is true because its truth is indirect correspondence to the world. After offering further arguments for austere realism and addressing objections to it, Horgan and Potrc [hacek over c] consider various alternative austere ontologies. They advance a specific version they call "blobjectivism"--the view that the right ontology includes only one concrete particular, the entire cosmos, which, although it has enormous local spatiotemporal variability, does not have any proper parts. The arguments in Austere Realism are powerfully made and concisely and lucidly set out. The authors' contentions and their methodological approach--products of a decade-long collaboration--will generate lively debate among scholars in metaphysics, ontology, and philosophy. Terence E. Horgan is Professor of Philosophy at the University of Arizona. Matjaz [hacek over z] Potrc [hacek over c] is Professor of Philosophy at the University of Ljubljana. (shrink)