Department of History and Philosophy of Science. University of Cambridge, Free School Lane, Cambridge CB2 3RH This paper is concerned with the question of whether atomic particles of the same species, i. e. with the same intrinsic state-independent properties of mass, spin, electric charge, etc, violate the Leibnizian Principle of the Identity of Indiscernibles, in the sense that, while there is more than one of them, their state-dependent properties may also all be the same. The answer depends on what exactly (...) the state-dependent properties of atomic particles are taken to be. On the plausible interpretation that these should comprise all monadic and relational properties that can be expressed in terms of physical magnitudes associated with self-adjoint operators that can be defined for the individual particles, then the weakest form of the Principle is shown to be violated for bosons, fermions and higher-order paraparticles, treated in first quantization *Some of the arguments inn this paper appeared in a thesis submited by one of us (S.F.) In partial fulfilment of the requirements for the PhD degree of the University of London, in 1984. entitled 'Identity and ‘Individuality in Classical and Quantum Physics’. (shrink)

Fearful Symmetry brings the incredible discoveries of contemporary physics within everyone's grasp. A. Zee, a distinguished physicist and skillful expositor, tells the exciting story of how today's theoretical physicists are following Einstein in their search for the beauty and simplicity of Nature. Animated by a sense of reverence and whimsy, the book describes the majestic sweep and accomplishments of twentieth-century physics. In the end, we stand in awe before the grand vision of modern physics--one of the greatest (...) chapters in the intellectual history of humankind. (shrink)

From an early age, humans know a surprising amount about basic physical principles, such as gravity, force, mass, and shape. We can see this in the way that young children play, and manipulate objects around them. The same behaviour has long been observed in primates - chimpanzees have been shown to possess a remarkable ability to make and use simple tools. But what does this tell us about their inner mental state - do they therefore share the same understanding to (...) that of a young child? Do they understand the simple, underlying physical principles involved? Though some people would say that they do, this book reports groundbreaking research that questions whether this really is the case. -/- Folk Physics for Apes challenges the assumptions so often made about apes. It offers us a rare glimpse into the workings of another mind, examining how apes perceive and understand the physical world - an understanding that appears to be both similar to, and yet profoundly different from our own. The book will have broad appeal to evolutionary psychologists, developmental psychologists, and those interested in the sub-disciplines of cognitive science (philosophy, anthropology). The book additionally offers for developmental psychologists some valuable new non-verbal techniques for assessing causal understanding in young children. (shrink)

In this paper I will defend the incapacity of the informational frameworks in thermal physics, mainly those that historically and conceptually derive from the work of Brillouin (1962) and Jaynes (1957a), to robustly explain the approach of certain gaseous systems to their state of thermal equilibrium from the dynamics of their molecular components. I will further argue that, since their various interpretative, conceptual and technical-formal resources (e.g. epistemic interpretations of probabilities and entropy measures, identification of thermal entropy as Shannon (...) information, and so on) are shown to be somehow incoherent, inconsistent or inaccurate, these informational proposals need to 'epistemically parasitize' the manifold of theoretical resources of Boltzmann's and Gibbs' statistical mechanics, respectively, in order to properly account for the equilibration process of an ideal gas from its microscopic properties. Finally, our conclusion leads us to adopt a sort of constructive skepticism regarding the explanatory value of the main informationalist trends in statistical thermophysics. (shrink)

It is shown that the Hilbert-Bernays-Quine principle of identity of indiscernibles applies uniformly to all the contentious cases of symmetries in physics, including permutation symmetry in classical and quantum mechanics. It follows that there is no special problem with the notion of objecthood in physics. Leibniz's principle of sufficient reason is considered as well; this too applies uniformly. But given the new principle of identity, it no longer implies that space, or atoms, are unreal.

entry for the Stanford Encyclopedia of Philosophy (SEP) This entry will attempt to provide a broad overview of the central themes of Leibniz’s philosophy of physics, as well as an introduction to some of the principal arguments and argumentative strategies he used to defend his positions. It tentatively includes sections entitled, The Historical Development of Leibniz’s Physics, Leibniz on Matter, Leibniz’s Dynamics, Leibniz on the Laws of Motion, Leibniz on Space and Time. A bibliography arranged by topic is (...) also included. A working draft is available here (comments, as always welcome): draft. (shrink)

Highlighting main issues and controversies, this book brings together current philosophical discussions of symmetry in physics to provide an introduction to the subject for physicists and philosophers. The contributors cover all the fundamental symmetries of modern physics, such as CPT and permutation symmetry, as well as discussing symmetry-breaking and general interpretational issues. Classic texts are followed by new review articles and shorter commentaries for each topic. Suitable for courses on the foundations of physics, philosophy of physics (...) and philosophy of science, the volume is a valuable reference for students and researchers. (shrink)

This is a comprehensive discussion of complexity as it arises in physical, chemical, and biological systems, as well as in mathematical models of nature. Common features of these apparently unrelated fields are emphasised and incorporated into a uniform mathematical description, with the support of a large number of detailed examples and illustrations. The quantitative study of complexity is a rapidly developing subject with special impact in the fields of physics, mathematics, information science, and biology. Because of the variety of (...) the approaches, no comprehensive discussion has previously been attempted. This book will be of interest to graduate students and researchers in physics (nonlinear dynamics, fluid dynamics, solid-state, cellular automata, stochastic processes, statistical mechanics and thermodynamics), mathematics (dynamical systems, ergodic and probability theory), information and computer science (coding, information theory and algorithmic complexity), electrical engineering and theoretical biology. (shrink)

Mark Wilson explores our strategies for understanding the world. We frequently cannot reason about nature in the straightforward manner we anticipate, but must use alternative thought processes that reach useful answers in opaque and roundabout ways; and philosophy must find better descriptive tools to reflect this.

The article sets out a primitive ontology of the natural world in terms of primitive stuff—that is, stuff that has as such no physical properties at all—but that is not a bare substratum either, being individuated by metrical relations. We focus on quantum physics and employ identity-based Bohmian mechanics to illustrate this view, but point out that it applies all over physics. Properties then enter into the picture exclusively through the role that they play for the dynamics of (...) the primitive stuff. We show that such properties can be local, as well as holistic, and discuss two metaphysical options to conceive them, namely, Humeanism and modal realism in the guise of dispositionalism. 1 Introduction2 Primitive Ontology: Primitive Stuff3 The Physics of Matter as Primitive Stuff4 The Humean Best System Analysis of the Dynamical Variables5 Modal Realism about the Dynamical Variables6 Conclusion. (shrink)

This article explores three ways in which physics may involve counterpossible reasoning. The first way arises when evaluating false theories: to say what the world would be like if the theory were true, we need to evaluate counterfactuals with physically impossible antecedents. The second way relates to the role of counterfactuals in characterizing causal structure: to say what causes what in physics, we need to make reference to physically impossible scenarios. The third way is novel: to model metaphysical (...) dependence in physics, we need to consider counterfactual consequences of metaphysical impossibilities. Physics accordingly bears substantial and surprising counterpossible commitments. (shrink)

Roughly speaking, classical statistical physics is the branch of theoretical physics that aims to account for the thermal behaviour of macroscopic bodies in terms of a classical mechanical model of their microscopic constituents, with the help of probabilistic assumptions. In the last century and a half, a fair number of approaches have been developed to meet this aim. This study of their foundations assesses their coherence and analyzes the motivations for their basic assumptions, and the interpretations of their (...) central concepts. The most outstanding foundational problems are the explanation of time-asymmetry in thermal behaviour, the relative autonomy of thermal phenomena from their microscopic underpinning, and the meaning of probability. A more or less historic survey is given of the work of Maxwell, Boltzmann and Gibbs in statistical physics, and the problems and objections to which their work gave rise. Next, we review some modern approaches to (i) equilibrium statistical mechanics, such as ergodic theory and the theory of the thermodynamic limit; and to (ii) non-equilibrium statistical mechanics as provided by Lanford's work on the Boltzmann equation, the so-called Bogolyubov-Born-Green-Kirkwood-Yvon approach, and stochastic approaches such as `coarse-graining' and the `open systems' approach. In all cases, we focus on the subtle interplay between probabilistic assumptions, dynamical assumptions, initial conditions and other ingredients used in these approaches. (shrink)

A widespread view in physics holds that the implementation of time reversal in standard quantum mechanics must be given by an anti-unitary operator. In foundations and philosophy of physics, however, there has been some discussion about the conceptual grounds of this orthodoxy, largely relying on either its obviousness or its mathematical-physical virtues. My aim in this paper is to substantively change the traditional structure of the debate by highlighting the philosophical commitments underlying the orthodoxy. I argue that the (...) persuasive force of the orthodoxy can benefit from a relational metaphysics of time and a by-stipulation view on symmetries. Within such philosophical background, I submit, the orthodoxy of time reversal in standard quantum mechanics could find a fertile terrain to lay the groundwork for a more thorough conceptual justification. (shrink)

I am a theoretical physicist, and, following Aristotles' injunction (Aristotle, Physics III, 202b 34), I do consider it my responsibility to discuss the problem of the notion of infinity in the world--in particular, to "inquire whether there is such a thing or not." I will do so here by illustrating some aspects of the notion of infinity in the natural sciences.

Contrary to claims about the irrelevance of philosophy for science, I argue that philosophy has had, and still has, far more influence on physics than is commonly assumed. I maintain that the current anti-philosophical ideology has had damaging effects on the fertility of science. I also suggest that recent important empirical results, such as the detection of the Higgs particle and gravitational waves, and the failure to detect supersymmetry where many expected to find it, question the validity of certain (...) philosophical assumptions common among theoretical physicists, inviting us to engage in a clearer philosophical reflection on scientific method. (shrink)

The goal of this essay is twofold. First, it provides a quick look at the foundations of modern relational mechanics by tracing its development from Julian Barbour and Bruno Bertotti's original ideas until present-day's pure shape dynamics. Secondly, it discusses the most appropriate metaphysics for pure shape dynamics, showing that relationalism is more of a nuanced thesis rather than an elusive one. The chapter ends with a brief assessment of the prospects of pure shape dynamics in light of quantum (...) class='Hi'>physics. (shrink)

This volume offers a broad, philosophical discussion on mechanical explanations. Coverage ranges from historical approaches and general questions to physics and higher-level sciences . The contributors also consider the topics of complexity, emergence, and reduction. Mechanistic explanations detail how certain properties of a whole stem from the causal activities of its parts. This kind of explanation is in particular employed in explanatory models of the behavior of complex systems. Often used in biology and neuroscience, mechanistic explanation models have been (...) often overlooked in the philosophy of physics. The authors correct this surprising neglect. They trace these models back to their origins in physics. The papers present a comprehensive historical, methodological, and problem-oriented investigation. The contributors also investigate the conditions for using models of mechanistic explanations in physics. The last papers make the bridge from physics to economics, the theory of complex systems and computer science . This book will appeal to graduate students and researchers with an interest in the philosophy of science, scientific explanation, complex systems, models of explanation in physics higher level sciences, and causal mechanisms in science. (shrink)

In this paper, I examine some of the most important theories of modern physics that support the notion that events are the basic ontological units of reality. The two main themes of this paper include: (1) physical evidence in support of an ontology of events, and (2) the increasing unification of physical theory until we arrive at the current state of two highly successful theories that are presently disunified within the search for a comprehensive, unified theory. With the revolutionary (...) developments in physics at the end of the nineteenth century, the mechanistic materialism of Newtonian physics began to break down and the ancient trinity of space, time and matter has been gradually replaced by the notion of the energy field. Physicists and philosophers who have held an event ontology specifically for its compatibility with electromagnetism, relativity theory and quantum mechanics include: Albert Einstein, Alfred North Whitehead, Bertrand Russell, C. D. Broad, W. V. Quine, John Bell, Henry Stapp, and Milič Čapek among many others. For these theorists, events are the most fundamental entities of physical reality in contrast to the Aristotelian tradition which contends that events are secondary or dependent on physical substance. (shrink)

We discuss the relationship between the interpretative problems of quantum gravity and those of general relativity. We argue that classical and quantum theories of gravity resuscitate venerable philosophical questions about the nature of space, time, and change; and that the resolution of some of the difficulties facing physicists working on quantum theories of gravity would appear to require philosophical as well as scientific creativity.

Theologians and philosophers of religion are increasingly interested in physics. From the fine-tuning of universal constants to quantum mechanics, relativity, and cosmology, physics is a surprisingly common subject where religion is involved. Bridging the gap between issues in religion and those in physics can be quite difficult, however. Fortunately, the philosophy of science provides a middle ground between the two disciplines. In this book, a philosopher of science provides a critical analysis of the ways in which (...) class='Hi'>physics is brought into play in matters of religion. (shrink)

Hopkins' Idealism provides a thorough re-examination of the nineteenth-century poet Gerard Manley Hopkins (1844-1889), whose early writings on philosophy have to date received little critical attention. It is the first full-length study of Hopkins' largely unpublished Oxford undergraduate essays and notes on philosophy and mechanics. The volume also offers radical new readings of some of Hopkins' best-known poems.

This paper makes a novel linkage between the multiple-computations theorem in philosophy of mind and Landauer’s principle in physics. The multiple-computations theorem implies that certain physical systems implement simultaneously more than one computation. Landauer’s principle implies that the physical implementation of “logically irreversible” functions is accompanied by minimal entropy increase. We show that the multiple-computations theorem is incompatible with, or at least challenges, the universal validity of Landauer’s principle. To this end we provide accounts of both ideas in terms (...) of low-level fundamental concepts in statistical mechanics, thus providing a deeper understanding of these ideas than their standard formulations given in the high-level terms of thermodynamics and cognitive science. Since Landauer’s principle is pivotal in the attempts to derive the universal validity of the second law of thermodynamics in statistical mechanics, our result entails that the multiple-computations theorem has crucial implications with respect to the second law. Finally, our analysis contributes to the understanding of notions, such as “logical irreversibility,” “entropy increase,” “implementing a computation,” in terms of fundamental physics, and to resolving open questions in the literature of both fields, such as: what could it possibly mean that a certain physical process implements a certain computation. (shrink)

A conventional wisdom about the progress of physics holds that successive theories wholly encompass the domains of their predecessors through a process that is often called reduction. While certain influential accounts of inter-theory reduction in physics take reduction to require a single "global" derivation of one theory's laws from those of another, I show that global reductions are not available in all cases where the conventional wisdom requires reduction to hold. However, I argue that a weaker "local" form (...) of reduction, which defines reduction between theories in terms of a more fundamental notion of reduction between models of a single fixed system, is available in such cases and moreover suffices to uphold the conventional wisdom. To illustrate the sort of fixed-system, inter-model reduction that grounds inter-theoretic reduction on this picture, I specialize to a particular class of cases in which both models are dynamical systems. I show that reduction in these cases is underwritten by a mathematical relationship that follows the broad prescriptions of Nagel/Schaffner reduction, and support this claim with several examples. Moreover, I show that this broadly Nagelian analysis of inter-model reduction encompasses several cases that are sometimes cited as instances of the "physicist's" limit-based notion of reduction. (shrink)

The Principle of Sufficient Reason (PSR) holds that, for everything that exists or occurs or holds true, there is a reason why that is the case. I consider three possible ways of relating physics to the PSR: past states as reasons for present states, reasons why the laws of physics take the form that they do, and reasons why there is anything at all. In each case I suggest that the PSR is not the best way of thinking (...) about how and why physics works. -/- Invited reflection for The Principle of Sufficient Reason (Oxford Philosophical Concepts), Eds. F. Amijee and M. Della Rocca (forthcoming 2024). (shrink)

This monograph presents the latest findings from a long-term research project intended to identify the physics behind Quantum Mechanics. A fundamental theory for quantum mechanics is constructed from first physical principles, revealing quantization as an emergent phenomenon arising from a deeper stochastic process. As such, it offers the vibrant community working on the foundations of quantum mechanics an alternative contribution open to discussion. The book starts with a critical summary of the main conceptual problems that still beset quantum mechanics. (...) The basic consideration is then introduced that any material system is an open system in permanent contact with the random zero-point radiation field, with which it may reach a state of equilibrium. Working from this basis, a comprehensive and self-consistent theoretical framework is then developed. The pillars of the quantum-mechanical formalism are derived, as well as the radiative corrections of nonrelativistic QED, while revealing the underlying physical mechanisms. The genesis of some of the central features of quantum theory is elucidated, such as atomic stability, the spin of the electron, quantum fluctuations, quantum nonlocality, and entanglement. The theory developed here reaffirms fundamental scientific principles such as realism, causality, locality and objectivity. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Physics and Metaphysics in Descartes and GalileoBlake D. Duttonin his classic biography of Descartes, Charles Adam passes this judgment on the influence of Galileo’s condemnation on the development of Cartesian metaphysics:Sans la condemnation de Galilée, nous aurions eu tout de même la métaphysique de Descartes. Mais nous ne l’aurions problement pas eue sous la forme volumineuse qu’elle a prise avec toutes ces Objections et Reponses, qui font plus (...) que quintupler les Méditations primitives.1(AT XII, 306)While not charging Descartes with dissimulation, Adam argues that the metaphysics was developed to deflect attention from the heart of the Cartesian system—its mechanistic physics—which posed a direct challenge to the reigning Aristotelianism. In his words, it served primarily as a “tent... to cover the merchandise (le pavilion... couvrir la marchandise)”(AT XII, 306).2Adam is certainly not alone in pointing to the Galileo affair as grounds for raising suspicions about the role of the metaphysics in Descartes’ larger work. In a recent biography, itself destined to become a classic, Stephen Gaukroger takes a similar line, arguing that it was Galileo’s failure to convince his opponents through arguments drawn from natural philosophy that prompted Descartes to seek acceptance of his own natural philosophy though metaphysical legitimation. Had Galileo not been silenced there would have been no impetus for Descartes to have developed a metaphysical argument; natural-philosophical [End Page 49] arguments would have sufficed.3 Thus, in the words of Gaukroger, Descartes’ project of metaphysical legitimation was “a task which he never even contemplated before the condemnation of Galileo in 1633, and... was a direct response to that condemnation.”4 If we are to believe Adam and Gaukroger, then, Descartes was first and foremost a natural philosopher whose extended venture into metaphysics was primarily a strategic response to the events of 1633.Despite the many merits of this line of interpretation, I believe it is trouble-some insofar as it isolates Descartes’ reaction to the condemnation from both his criticisms of Galileo’s science and his views on the relation between science and theology. In doing so, it overstates the degree to which Cartesian science can itself be isolated from Cartesian metaphysics. In what follows, then, I will contextualize Descartes’ reaction to the Galileo affair by examining his comments on Galileo’s scientific work and the relation of his own views on science and theology to those of Galileo. Two results will emerge. First, we will see that if we fail to take Descartes’ search for metaphysical foundations as having a genuinely scientific motivation, not only will we render his criticisms of Galileo’s science unintelligible, but we will fail to understand the distinctive nature of his science vis-à-vis Galileo’s. This will become clear as we examine the work of each on motion and the fall of bodies. Second, we will see that it is only by taking Descartes’ metaphysical commitments as integral to his science that we can make sense of the divergent ways in which he and Galileo resolved the question of the relation of science to theology. Both, it is clear, sought to guarantee the autonomy of science, yet each did so in a way which mirrored his unique conception of science and its relation to metaphysics. All of this, I conclude, deflates the utility of appealing to Descartes’ concern over the Galileo affair as a means of assigning a primarily strategic or extra-scientific role to his metaphysics. [End Page 50]1. descartes on galilean scienceAlthough they were contemporaries, there is no evidence that Descartes and Galileo ever met or corresponded. There is also no strong evidence that the work of either had any significant influence on the work of the other, despite the fact that Descartes reports having leafed through the Dialogue Concerning the Two Chief World Systems and having obtained a copy of the Two New Sciences.5 However, we do find several references to Galileo in Descartes’ correspondence from which a general attitude toward the Italian scientist becomes reasonably clear. While occasionally being complimentary, Descartes appears to have been largely unimpressed and even claims to have arrived at several... (shrink)

Three studies were conducted to examine the relation of spatial visualization to solving kinematics problems that involved either predicting the two‐dimensional motion of an object, translating from one frame of reference to another, or interpreting kinematics graphs. In Study 1, 60 physics‐naíve students were administered kinematics problems and spatial visualization ability tests. In Study 2, 17 (8 high‐ and 9 low‐spatial ability) additional students completed think‐aloud protocols while they solved the kinematics problems. In Study 3, the eye movements of (...) fifteen (9 high‐ and 6 low‐spatial ability) students were recorded while the students solved kinematics problems. In contrast to high‐spatial students, most low‐spatial students did not combine two motion vectors, were unable to switch frames of reference, and tended to interpret graphs literally. The results of the study suggest an important relationship between spatial visualization ability and solving kinematics problems with multiple spatial parameters. (shrink)

This article provides a non-technical overview of the conflict between the special theory of relativity and the dynamic theories of time. The chief argument against dynamic theories of time from relativistic mechanics is presented. The space of current responses to that argument is subsequently mapped.

I provide a critical commentary regarding the attitude of the logician and the philosopher towards the physicist and physics. The commentary is intended to showcase how a general change in attitude towards making scientific inquiries can be beneficial for science as a whole. However, such a change can come at the cost of looking beyond the categories of the disciplines of logic, philosophy and physics. It is through self-inquiry that such a change is possible, along with the realization (...) of the essence of the middle that is otherwise excluded by choice. The logician, who generally holds a reverential attitude towards the physicist, can then actively contribute to the betterment of physics by improving the language through which the physicist expresses his experience. The philosopher, who otherwise chooses to follow the advancement of physics and gets stuck in the trap of sophistication of language, can then be of guidance to the physicist on intellectual grounds by having the physicist’s experience himself. In course of this commentary, I provide a glimpse of how a truthful conversion of verbal statements to physico-mathematical expressions unravels the hitherto unrealized connection between Heisenberg uncertainty relation and Cauchy’s definition of derivative that is used in physics. The commentary can be an essential reading if the reader is willing to look beyond the categories of logic, philosophy and physics by being ‘nobody’. (shrink)

Physics underlies all complexity, including our own existence: how is this possible? How can our own lives emerge from interactions of electrons, protons, and neutrons? This book considers the interaction of physical and non-physical causation in complex systems such as living beings, and in particular in the human brain, relating this to the emergence of higher levels of complexity with real causal powers. In particular it explores the idea of top-down causation, which is the key effect allowing the emergence (...) of true complexity and also enables the causal efficacy of non-physical entities, including the value of money, social conventions, and ethical choices. (shrink)