According to the Gottesman–Knill theorem, quantum algorithms that utilize only the operations belonging to a certain restricted set are efficiently simulable classically. Since some of the operations in this set generate entangled states, it is commonly concluded that entanglement is insufficient to enable quantum computers to outperform classical computers. I argue in this article that this conclusion is misleading. First, the statement of the theorem is, on reflection, already evident when we consider Bell’s and related inequalities in the context of (...) a discussion of computational machines. This, in turn, helps us to understand that the appropriate conclusion to draw from the Gottesman–Knill theorem is not that entanglement is insufficient to enable a quantum performance advantage, but rather that if we limit ourselves to the operations referred to in the Gottesman–Knill theorem, we will not have used the resources provided by an entangled quantum system to their full potential. (shrink)

Although computation and the science of physical systems would appear to be unrelated, there are a number of ways in which computational and physical concepts can be brought together in ways that illuminate both. This volume examines fundamental questions which connect scholars from both disciplines: is the universe a computer? Can a universal computing machine simulate every physical process? What is the source of the computational power of quantum computers? Are computational approaches to solving physical problems and paradoxes always fruitful? (...) Contributors from multiple perspectives reflecting the diversity of thought regarding these interconnections address many of the most important developments and debates within this exciting area of research. Both a reference to the state of the art and a valuable and accessible entry to interdisciplinary work, the volume will interest researchers and students working in physics, computer science, and philosophy of science and mathematics. (shrink)

I argue that our judgements regarding the locally causal models that are compatible with a given constraint implicitly depend, in part, on the context of inquiry. It follows from this that certain quantum no-go theorems, which are particularly striking in the traditional foundational context, have no force when the context switches to a discussion of the physical systems we are capable of building with the aim of classically reproducing quantum statistics. I close with a general discussion of the possible implications (...) of this for our understanding of the limits of classical description, and for our understanding of the fundamental aim of physical investigation. _1_ Introduction _2_ No-Go Results _2.1_ The CHSH inequality _2.2_ The GHZ equality _3_ Classically Simulating Quantum Statistics _3.1_ GHZ statistics _3.2_ Singlet statistics _4_ What Is a Classical Computer Simulation? _5_ Comparing the All-or-Nothing GHZ with Statistical equalities _6_ General Discussion _7_ Conclusion. (shrink)

A primary goal of quantum computer science is to find an explanation for the fact that quantum computers are more powerful than classical computers. In this paper I argue that to answer this question is to compare algorithmic processes of various kinds and to describe the possibility spaces associated with these processes. By doing this, we explain how it is possible for one process to outperform its rival. Further, in this and similar examples little is gained in subsequently asking a (...) how-actually question. Once one has explained how-possibly, there is little left to do. (shrink)

From the philosopher’s perspective, the interest in quantum computation stems primarily from the way that it combines fundamental concepts from two distinct sciences: Physics, in particular Quantum Mechanics, and Computer Science, each long a subject of philosophical speculation and analysis in its own right. Quantum computing combines both of these more traditional areas of inquiry into one wholly new, if not quite independent, science. Over the course of this chapter we will be discussing some of the most important philosophical questions (...) that arise from this merger and philosophical lessons to be learned. (shrink)

It is argued that those who defend the Everett, or ‘many-worlds’, interpretation of quantum mechanics should embrace what we call the general quantum theory of open systems (GT) as the proper framework in which to conduct foundational and philosophical investigations in quantum physics. GT is a wider dynamical framework than its alternative, standard quantum theory (ST). This is true even though GT makes no modifications to the quantum formalism. GT rather takes a different view, what we call the open systems (...) view, of the formalism; i.e., in GT, the dynamics of systems whose physical states are fundamentally represented by density operators are represented as fundamentally open as specified by an in general non-unitary dynamical map. This includes, in principle, the dynamics of the universe as a whole. We argue that the more general dynamics describable in GT can be physically motivated, that there is as much prima facie empirical support for GT as there is for ST, and that GT could be fully in the spirit of the Everett interpretation—that there might, in short, be little reason for an Everettian not to embrace the more general theoretical landscape that GT allows one to explore. (shrink)

There is a deeply entrenched view in philosophy and physics, the closed systems view, according to which isolated systems are conceived of as fundamental. On this view, when a system is under the influence of its environment this is described in terms of a coupling between it and a separate system which taken together are isolated. We argue against this view, and in favor of the alternative open systems view, for which systems interacting with their environment are conceived of as (...) fundamental, and the environment's influence is represented via the dynamical equations that govern the system's evolution. Taking quantum theories of closed and open systems as our case study, and considering three alternative notions of fundamentality: (i) ontic fundamentality, (ii) epistemic fundamentality, and (iii) explanatory fundamentality, we argue that the open systems view is fundamental, and that this has important implications for the philosophy of physics, the philosophy of science, and for metaphysics. (shrink)

I argue that the many worlds explanation of quantum computation is not licensed by, and in fact is conceptually inferior to, the many worlds interpretation of quantum mechanics from which it is derived. I argue that the many worlds explanation of quantum computation is incompatible with the recently developed cluster state model of quantum computation. Based on these considerations I conclude that we should reject the many worlds explanation of quantum computation.

The principle of 'information causality' can be used to derive an upper bound---known as the 'Tsirelson bound'---on the strength of quantum mechanical correlations, and has been conjectured to be a foundational principle of nature. In this paper, however, I argue that the principle has not to date been sufficiently motivated to play this role; the motivations that have so far been given are either unsatisfactorily vague or else amount to little more than an appeal to intuition. I then consider how (...) one might begin to successfully motivate the principle. I argue that a compelling way of so doing is to understand it as a generalisation of Einstein's principle of the mutually independent existence---the 'being-thus'---of spatially distant things, interpreted as a special methodological principle. More specifically: I describe an argument, due to Demopoulos, to the effect that the quantum-mechanical no-signalling condition can be viewed as a generalisation, appropriate to an irreducibly statistical theory such as quantum mechanics, of the Einsteinian principle. And I then argue that a compelling way to motivate information causality is to in turn consider it as a further generalisation of the Einsteinian principle that is appropriate to a theory of communication. I nevertheless describe important obstacles that must yet be overcome if the project of establishing information causality as a foundational principle of nature is to succeed. (shrink)

This book offers a thorough technical elaboration and philosophical defense of an objectivist informational interpretation of quantum mechanics according to which its novel content is located in its kinematical framework, that is, in how the theory describes systems independently of the specifics of their dynamics. -/- It will be of interest to researchers and students in the philosophy of physics and in theoretical physics with an interest in the foundations of quantum mechanics. Additionally, parts of the book may be used (...) as the basis for courses introducing non-physics majors to quantum mechanics, or for self-study by those outside of the university with an interest in quantum mechanics. (shrink)

I argue that Immanuel Kant's critical philosophy—in particular the doctrine of transcendental idealism which grounds it—is best understood as an `epistemic' or `metaphilosophical' doctrine. As such it aims to show how one may engage in the natural sciences and in metaphysics under the restriction that certain conditions are imposed on our cognition of objects. Underlying Kant's doctrine, however, is an ontological posit, of a sort, regarding the fundamental nature of our cognition. This posit, sometimes called the `discursivity thesis', while considered (...) to be completely obvious and uncontroversial by some, has nevertheless been denied by thinkers both before and after Kant. One such thinker is Jakob Friedrich Fries, an early neo-Kantian thinker who, despite his rejection of discursivity, also advocated for a metaphilosophical understanding of critical philosophy. As I will explain, a consequence for Fries of the denial of discursivity is a radical reconceptualisation of the method of critical philosophy; whereas this method is a priori for Kant, for Fries it is in general empirical. I discuss these issues in the context of quantum theory, and I focus in particular on the views of the physicist Niels Bohr and the Neo-Friesian philosopher Grete Hermann. I argue that Bohr's understanding of quantum mechanics can be seen as a natural extension of an orthodox Kantian viewpoint in the face of the challenges posed by quantum theory, and I compare this with the extension of Friesian philosophy that is represented by Hermann's view. -/- A shorter version of this paper, focusing specifically on the views of Grete Hermann, has been published as: Cuffaro, Michael (2023). Grete Hermann, Quantum Mechanics, and the Evolution of Kantian Philosophy. In Jeanne Peijnenburg & Sander Verhaegh (eds.), Women in the History of Analytic Philosophy. Cham: Springer. pp. 114-145. (shrink)

There has been a long-standing and sometimes passionate debate between physicists over whether a dynamical framework for quantum systems should incorporate not completely positive (NCP) maps in addition to completely positive (CP) maps. Despite the reasonableness of the arguments for complete positivity, we argue that NCP maps should be allowed, with a qualification: these should be understood, not as reflecting ‘not completely positive’ evolution, but as linear extensions, to a system’s entire state space, of CP maps that are only partially (...) defined. Beyond the domain of definition of a partial-CP map, we argue, much may be permitted. (shrink)

I argue that Kant's and Frege's refutations of the ontological argument are more similar than has generally been acknowledged. As I clarify, for both Kant and Frege, to say that something exists is to assert of a concept that it is instantiated. With such an assertion one expresses that there is a particular relation between the instantiating object and a rational subject - a particular mode of presentation for the object in question. By its very nature such a relation cannot (...) be the property of an object and thus cannot be included in the concept of that object. Thus the ontological argument, which takes existence to be a part of the concept of the supreme being, cannot, according to Kant and Frege, succeed. A secondary goal of the paper is to illuminate what I take to be an important affinity between Kant's and Frege's views more generally: that Frege's fundamental distinction between the sense and the referent of a proposition echoes, in an important way, Kant's distinction between concepts and the formal principles for their application to experience. (shrink)

I flesh out the sense in which the informational approach to interpreting quantum mechanics, as defended by Pitowsky and Bub and lately by a number of other authors, is (neo-)Bohrian. I argue that on this approach, quantum mechanics represents what Bohr called a “natural generalisation of the ordinary causal description” in the sense that the idea (which philosophers of science like Stein have argued for on the grounds of practical and epistemic necessity) that understanding a theory as a theory of (...) physics requires that one be able to “schematise the observer” within it is elevated in quantum mechanics to the level of a postulate in the sense that interpreting the outcome of a measurement interaction, as providing us with information about the world, requires as a matter of principle, the specification of a schematic representation of an observer in the form of a ‘Boolean frame’—the Boolean algebra representing the yes-or-no questions associated with a given observable representative of a given experimental context. I argue that the approach’s central concern is with the methodological question of how to assign physical properties to what one takes to be a system in a given experimental context, rather than the metaphysical question of what a given state vector represents independently of any context, and I show how the quantum generalisation of the concept of an open system may be used to assuage Einstein’s complaint that the orthodox approach to quantum mechanics runs afoul of the supposedly fundamental methodological requirement to the effect that one must always be able, according to Einstein, to treat spatially separated systems as isolated from one another. (shrink)

Wittgenstein did not write very much on the topic of probability. The little we have comes from a few short pages of the Tractatus, some 'remarks' from the 1930s, and the informal conversations which went on during that decade with the Vienna Circle. Nevertheless, Wittgenstein's views were highly influential in the later development of the logical theory of probability. This paper will attempt to clarify and defend Wittgenstein's conception of probability against some oft-cited criticisms that stem from a misunderstanding of (...) his views. Max Black, for instance, criticises Wittgenstein for formulating a theory of probability that is capable of being used only against the backdrop of the ideal language of the Tractatus. I argue that on the contrary, by appealing to the 'hypothetical laws of nature', Wittgenstein is able to make sense of probability statements involving propositions that have not been completely analysed. G.H. von Wright criticises Wittgenstein's characterisation of these very hypothetical laws. He argues that by introducing them Wittgenstein makes what is distinctive about his theory superfluous, for the hypothetical laws are directly inspired by statistical observations and hence these observations indirectly determine the mechanism by which the logical theory of probability operates. I argue that this is not the case at all, and that while statistical observations play a part in the formation of the hypothetical laws, these observations are only necessary, but not sufficient conditions for the introduction of these hypotheses. (shrink)

There has, as of late, emerged a promising strand in the historical and philosophical literature on Bohr that focuses on the central importance assigned in his view to the details of the experimental context under which observations of the systems described by quantum theory are made. Perovic’s book, which I summarize in the first part of this review, belongs to this tradition. The book is not without its shortcomings, which I summarize in the second part of this review, but overall (...) it is a plausible, accessible, and illuminating presentation of Bohr’s views that should be of interest to both historians and philosophers of science. (shrink)

This is an extended essay review of Tanya and Jeffrey Bub’s Totally Random: Why Nobody Understands Quantum Mechanics: A serious comic on entanglement. We review the philosophical aspects of the book, provide suggestions for instructors on how to use the book in a class setting, and evaluate the authors’ artistic choices in the context of comics theory. Although Totally Random does not defend any particular interpretation of quantum mechanics, we find that, in its mode of presentation, Totally Random is a (...) beautiful expression and illustration of the information-theoretic interpretation and its value. (shrink)

Combining physics, mathematics and computer science, quantum computing and its sister discipline of quantum information have developed in the past few decades from visionary ideas to two of the most fascinating areas of quantum theory. General interest and excitement in quantum computing was initially triggered by Peter Shor (1994) who showed how a quantum algorithm could exponentially “speed-up” classical computation and factor large numbers into primes far more efficiently than any (known) classical algorithm. Shor’s algorithm was soon followed by several (...) other algorithms that aimed to solve combinatorial and algebraic problems, and in the years since theoretical study of quantum systems serving as computational devices has achieved tremendous progress. Common belief has it that the implementation of Shor’s algorithm on a large scale quantum computer would have devastating consequences for current cryptography protocols which rely on the premise that all known classical worst-case algorithms for factoring take time exponential in the length of their input (see, e.g., Preskill 2005). Consequently, experimentalists around the world are engaged in attempts to tackle the technological difficulties that prevent the realisation of a large scale quantum computer. But regardless whether these technological problems can be overcome (Unruh 1995; Ekert and Jozsa 1996; Haroche and Raimond 1996), it is noteworthy that no proof exists yet for the general superiority of quantum computers over their classical counterparts. -/- The philosophical interest in quantum computing is manifold. From a social-historical perspective, quantum computing is a domain where experimentalists find themselves ahead of their fellow theorists. Indeed, quantum mysteries such as entanglement and nonlocality were historically considered a philosophical quibble, until physicists discovered that these mysteries might be harnessed to devise new efficient algorithms. But while the technology for harnessing the power of 50–100 qubits (the basic unit of information in the quantum computer) is now within reach (Preskill 2018), only a handful of quantum algorithms exist, and the question of whether these can truly outperform any conceivable classical alternative is still open. From a more philosophical perspective, advances in quantum computing may yield foundational benefits. For example, it may turn out that the technological capabilities that allow us to isolate quantum systems by shielding them from the effects of decoherence for a period of time long enough to manipulate them will also allow us to make progress in some fundamental problems in the foundations of quantum theory itself. Indeed, the development and the implementation of efficient quantum algorithms may help us understand better the border between classical and quantum physics (Cuffaro 2017, 2018a; cf. Pitowsky 1994, 100), and perhaps even illuminate fundamental concepts such as measurement and causality. Finally, the idea that abstract mathematical concepts such as computability and complexity may not only be translated into physics, but also re-written by physics bears directly on the autonomous character of computer science and the status of its theoretical entities—the so-called “computational kinds”. As such it is also relevant to the long-standing philosophical debate on the relationship between mathematics and the physical world. (shrink)

Radical ecology typically brings to mind media images of ecological activists standing before loggers' saws, staging anti-nuclear marches, and confronting polluters on the high seas. Yet for more than twenty years, the activities of organizations such as the Greens and Earth First! have been influenced by a diverse, less-publicized group of radical ecological philosophers. It is their work—the philosophical underpinnings of the radical ecological movement—that is the subject of _Contesting Earth's Future_. The book offers a much-needed, balanced appraisal of radical (...) ecology's principles, goals, and limitations. Michael Zimmerman critically examines the movement's three major branches—deep ecology, social ecology, and ecofeminism. He also situates radical ecology within the complex cultural and political terrain of the late twentieth century, showing its relation to Martin Heidegger's anti-technological thought, 1960s counterculturalism, and contemporary theories of poststructuralism and postmodernity. An early and influential ecological thinker, Zimmerman is uniquely qualified to provide a broad overview of radical environmentalism and delineate its various schools of thought. He clearly describes their defining arguments and internecine disputes, among them the charge that deep ecology is an anti-modern, proto-fascist ideology. Reflecting both the movement's promise and its dangers, this book is essential reading for all those concerned with the worldwide ecological crisis. (shrink)

"Writing in a lively and refreshingly clear American English, Zimmerman provides an uncompromisingly honest and judicious account... of Heidegger’s views on technology and his involvement with National Socialism.... One of the most important books on Heidegger in recent years." —John D. Caputo "... superb... " —Thomas Sheehan, The New York Review of Books "... thorough and complex... " —Choice "... excellent guide to Heidegger as eco-philosopher." —Radical Philosophy "... engrossing, rich in substance... makes clear Heidegger's importance for the issue of (...) technology, ethics, and politics." —Religious Studies Review The relation between Martin Heidegger’s understanding of technology and his affiliation with and conception of National Socialism is the leading idea of this fascinating and revealing book. Zimmerman shows that the key to the relation between Heidegger’s philosophy and his politics was his concern with the nature of working and production. (shrink)

Radical ecology typically brings to mind media images of ecological activists standing before loggers' saws, staging anti-nuclear marches, and confronting polluters on the high seas. Yet for more than twenty years, the activities of organizations such as the Greens and Earth First! have been influenced by a diverse, less-publicized group of radical ecological philosophers. It is their work—the philosophical underpinnings of the radical ecological movement—that is the subject of _Contesting Earth's Future_. The book offers a much-needed, balanced appraisal of radical (...) ecology's principles, goals, and limitations. Michael Zimmerman critically examines the movement's three major branches—deep ecology, social ecology, and ecofeminism. He also situates radical ecology within the complex cultural and political terrain of the late twentieth century, showing its relation to Martin Heidegger's anti-technological thought, 1960s counterculturalism, and contemporary theories of poststructuralism and postmodernity. An early and influential ecological thinker, Zimmerman is uniquely qualified to provide a broad overview of radical environmentalism and delineate its various schools of thought. He clearly describes their defining arguments and internecine disputes, among them the charge that deep ecology is an anti-modern, proto-fascist ideology. Reflecting both the movement's promise and its dangers, this book is essential reading for all those concerned with the worldwide ecological crisis. (shrink)

Ray Kurzweil and others have posited that the confluence of nanotechnology, artificial intelligence, robotics, and genetic engineering will soon produce posthuman beings that will far surpass us in power and intelligence. Just as black holes constitute a ldquo;singularityrdquo; from which no information can escape, posthumans will constitute a ldquo;singularity:rdquo; whose aims and capacities lie beyond our ken. I argue that technological posthumanists, whether wittingly or unwittingly, draw upon the long-standing Christian discourse of ldquo;theosis,rdquo; according to which humans are capable of (...) being God or god-like. From St. Paul and Luther to Hegel and Kurzweil, the idea of human self-deification plays a prominent role. Hegel in particular emphasizes that God becomes wholly actualized only in the process by which humanity achieves absolute consciousness. Kurzweil agrees that God becomes fully actual only through historical processes that illuminate and thus transform the entire universe. The difference is that for Kurzweil and many other posthumanists, our offspringmdash;the posthumansmdash;will carry out this extraordinary process. What will happen to Home sapiens in the meantime is a daunting question. (shrink)

These are replies to the discussions by Kirk Ludwig, Elizabeth Pacherie, Björn Petersson, Abraham Roth, and Thomas Smith of Michael E. Bratman, Shared Agency: A Planning Theory of Acting Together (Oxford University Press, 2014).

To what extent can Nietzsche's idea of the Overman be used in connection with transhumanist notions of highly advanced humans and even posthumans?

Empathy and Democracy argues that empathy plays a crucial role in enabling democratic deliberation to function the way it should.

Michel Haar's book strikes an admirable balance between a sympathetic analysis of, and a critical dialogue with Heidegger's work. In clear and elegant prose, Haar elucidates obscure passages and raises critical questions about issues that are usually ignored. He argues that despite Heidegger's preoccupation with the "history of being," he was also concerned with the "nonhistorical," that is, with what cannot be included within history. Heidegger maintained that the history of being began with the Greeks and culminates in modern technology, (...) defined as the disclosure of all entities as a completely available "standing reserve" that is useful for enhancing the endless drive for more power. Haar asks: Did Heidegger reduce being to its history? and as a result, did he develop his own version of Hegel's system of world history? Haar answers in the negative: "In effect the development of the history of Being from the Greek logos to modern technology does not exclude, but implies a reserve, an opacity, a reverse side [envers] that it is never possible to disclose. It is this withdrawn and non-manifest dimension that makes history a destiny, and not the logical unfolding that is in Hegel answerable to an eternal necessity". According to Haar, the earth constitutes the basis for the nonhistorical domain that cannot be encompassed within the history of being. (shrink)

We are purposive agents; but we—adult humans in a broadly modern world—are more than that. We are reflective about our motivation. We form prior plans and policies that organize our activity over time. And we see ourselves as agents who persist over time and who begin, develop, and then complete temporally extended activities and projects. Any reasonably complete theory of human action will need in some way to advert to this trio of features—to our reflectiveness, our planfulness, and our conception (...) of our agency as temporally extended. These are, further, features that have great significance for the kinds of lives we can live. For these two reasons I will say that these are among the core features of human agency. A theory of human action needs to say what these core features consist in and how they are related to each other. And such a theory needs also to clarify the relation between these core features of our agency and the possibility that we are fully embedded in an event causal order. (shrink)

Cases of modest sociality are cases of small scale shared intentional agency in the absence of asymmetric authority relations. I seek a conceptual framework that adequately supports our theorizing about such modest sociality. I want to understand what in the world constitutes such modest sociality. I seek an understanding of the kinds of normativity that are central to modest sociality. And throughout we need to keep track of the relations—conceptual, metaphysical, normative—between individual agency and modest sociality. In pursuit of these (...) theoretical aims, I propose that a central phenomenon is shared intention. I argue that an adequate understanding of the distinctiveness of the intentions of individuals allows us to provide a construction of attitudes of the participants, and of relevant inter-relations and contexts that constitutes shared intention. I explain how shared intention, so understood, differs from a simple equilibrium within common knowledge. And I briefly contrast my views with aspects of views of John Searle and Margaret Gilbert. (shrink)