The search for a quantum theory of the gravitational field is one of the great open problems in theoretical physics. This book presents a self-contained discussion of the concepts, methods and applications that can be expected in such a theory. The two main approaches to its construction - the direct quantisation of Einstein's general theory of relativity and string theory - are covered. Whereas the first attempts to construct a viable theory for the gravitational field alone, string theory assumes that (...) a quantum theory of gravity will be achieved only through a unification of all the interactions. However, both employ the general method of quantisation of constrained systems, which is described together with illustrative examples relevant for quantum gravity. There is a detailed presentation of the main approaches employed in quantum general relativity: path-integral quantisation, the background-field method and canonical quantum gravity in the metric, connection and loop formulations. The discussion of string theory centres around its quantum-gravitational aspects and the comparison with quantum general relativity. Physical applications discussed at length include the quantisation of black holes, quantum cosmology, the indications of a discrete structure of spacetime, and the origin of irreversibility. This book will be of interest to researchers and students working in relativity and gravitation, cosmology, quantum field theory and related topics. It will also be of interest to mathematicians and philosophers of science. (shrink)

Time is absolute in standard quantum theory and dynamical in general relativity. The combination of both theories into a theory of quantum gravity leads therefore to a “problem of time”. In my essay, I investigate those consequences for the concept of time that may be drawn without a detailed knowledge of quantum gravity. The only assumptions are the experimentally supported universality of the linear structure of quantum theory and the recovery of general relativity in the classical limit. Among the consequences (...) are the fundamental timelessness of quantum gravity, the approximate nature of a semiclassical time, and the correlation of entropy with the size of the Universe. (shrink)

I argue that quantum theory can, and in fact must, be applied to the Universe as a whole. After a general introduction, I discuss two concepts that are essential for my chain of arguments: the universality of quantum theory and the emergence of classical behaviors by decoherence. A further motivation is given by the open problem of quantum gravity. I then present the main ingredients of quantum cosmology and discuss their relevance for the interpretation of quantum theory. I end with (...) some brief epistemological remarks. (shrink)

The compact and, with \ M\, very massive object located at the center of the Milky Way is currently the very best candidate for a supermassive black hole in our immediate vicinity. The strongest evidence for this is provided by measurements of stellar orbits, variable X-ray emission, and strongly variable polarized near-infrared emission from the location of the radio source Sagittarius A* in the middle of the central stellar cluster. Simultaneous near-infrared and X-ray observations of SgrA* have revealed insights into (...) the emission mechanisms responsible for the powerful near-infrared and X-ray flares from within a few tens to one hundred Schwarzschild radii of such a putative SMBH. If SgrA* is indeed a SMBH it will, in projection onto the sky, have the largest event horizon and will certainly be the first and most important target for very long baseline interferometry observations currently being prepared by the event horizon telescope. These observations in combination with the infrared interferometry experiment GRAVITY at the very large telescope interferometer and other experiments across the electromagnetic spectrum might yield proof for the presence of a black hole at the center of the Milky Way. The large body of evidence continues to discriminate the identification of SgrA* as a SMBH from alternative possibilities. It is, however, unclear when the ever mounting evidence for SgrA* being associated with a SMBH will suffice as a convincing proof. Additional compelling evidence may come from future gravitational wave observatories. This manuscript reviews the observational facts, theoretical grounds and conceptual aspects for the case of SgrA* being a black hole. We treat theory and observations in the framework of the philosophical discussions about “realism and underdetermination”, as this line of arguments allows us to describe the situation in observational astrophysics with respect to supermassive black holes. Questions concerning the existence of supermassive black holes and in particular SgrA* are discussed using causation as an indispensable element. We show that the results of our investigation are convincingly mapped out by this combination of concepts. (shrink)

I address the question whether the wave function in quantum theory exists as a real quantity or not. For this purpose, I discuss the essentials of the quantum formalism and emphasize the central role of the superposition principle. I then explain the measurement problem and discuss the process of decoherence. Finally, I address the special features that the quantization of gravity brings into the game. From all of this I conclude that the wave function really exists, that is, it is (...) a real feature of Nature. (shrink)

Die Aufstellung einer vereinheitlichten Theorie der Naturbeschreibung gehört zu den bisher unerfüllten Wünschen der modernen Physik. In meinem Beitrag schildere ich die Gründe, die für die Existenz einer solchen Theorie sprechen und bespreche den gegenwärtigen Stand der Suche. Eine fundamentale Rolle spielt hierbei die Vereinigung von Gravitation und Quantentheorie.

Vom 30. Mai bis 1. Juni 1963 fand an der Cornell-Universität eine kleine Tagung zur Natur der Zeit statt, ausgerichtet von den aus Wien stammenden Astrophysikern Hermann Bondi und Thomas Gold. Kurt Gödel war nicht anwesend. Dabei hatte der berühmte Mathematiker etwa 15 Jahre zuvor Arbeiten veröffentlicht, die ganz wesentlich und weitreichend mit dem Begriff der Zeit zu tun hatten.

From 30 May to 1 June Cornell University hosted a small conference on the nature of time, organised by the originally Viennese astro-physicists Hermann Bondi and Thomas Gold. Kurt Gödel did not attend, although roughly 15 years earlier the famous mathematician had made a significant contribution to this field.

Nicht zufällig beginnt das theologische Nachdenken über Gut und Böse bis heute immer wieder mit den ersten Kapiteln der Genesis. Sie sind bewusst als Anfang der Tora konzipiert und wollen selbst vom Anfang erzählen - vom Anfang der Menschheit und darin auch vom Anfang des Guten und Bösen. Texte, die so im Fokus stehen, werden bekanntlich oft theologisch überfrachtet mit Interessen und Vorurteilen. Diese Untersuchung möchte die biblischen Texte von dogmatischem Ballast befreien und deren ureigenen Beitrag zu der immer noch (...) brisanten Frage nach Gut und Böse zur Sprache bringen. (shrink)

This chapter focuses on what’s novel in the perspective that the prediction error minimization (PEM) framework affords on the cognitive-scientific project of explaining intelligence by appeal to internal representations. It shows how truth-conditional and resemblance-based approaches to representation in generative models may be integrated. The PEM framework in cognitive science is an approach to cognition and perception centered on a simple idea: organisms represent the world by constantly predicting their own internal states. PEM theories often stress the hierarchical structure of (...) the generative models they posit. The novel explanatory power of the PEM account derives largely from the way in which pairs of generative and recognition models interact. “Predictive coding” refers to an encoding strategy in which predicted portions of an input signal are subtracted from the actual signal received, so that only the difference between the two is passed as output to the next stage of information processing. (shrink)

The ontological status of esse cognitum was at the center of complex debates throughout the Scotist tradition (Alnwick vs. Aesculo, Mastri vs. Punch). This article investigates the Scotist Angelo Volpe’s discussion of esse cognitum enjoyed by possible creatures in the divine intellect. Volpe responds to two religious warnings, one against assuming any eternal real being for merely possible creatures, and a second against depriving God’s eternal knowledge of a corresponding object, since that would endanger this knowledge itself. Volpe opts for (...) a solution that allows possible creatures the status of beings of reason (entia rationis) due to their own ontological merit, and the status of real beings (entia realia) due to God’s knowing that they as possibles are not in opposition to real existence. He rejects the view that esse cognitum is a kind of being that holds a middle position between real being and being of reason. Volpe’s historical significance is emphasized. (shrink)

Die Philosophie des Barockscotismus war einerseits durch die rückwärtsgewandte Anknüpfung an den mittelalterlichen Denker Johannes Duns Scotus, andererseits durch die Anknüpfung an die Entwicklung in der zeitgenössischen Scholastik, vor allem der Jesuitenscholastik, geprägt. Welche Art von Metaphysik hat diese besondere philosophiehistorische Konstellation hervorgebracht? Um diese Frage zu beantworten, analysiert die vorliegende Arbeit das Metaphysikwerk des wichtigsten Repräsentanten des frühneuzeitlichen Scotismus, Bartholomaeus Mastrius (1602-1673); sie erschließt außerdem eine Vielzahl von kaum bis gar nicht erforschten Metaphysikwerken aus der Franziskanerscholastik des 17. und (...) 18. Jahrhunderts. Das eigenartige, erstaunliche Vielfalt einschließende Profil einer in Vergessenheit geratenen philosophischen Tradition wird deutlich. Durch den Fokus auf ein philosophiehistorisches Phänomen außerhalb des Mainstreams leistet die Arbeit einen Beitrag zu einer differenzierteren Sichtweise der intellektuellen Kultur der europäischen Frühmoderne. Baroque-age Scotist philosophy was, on the one hand, characterised by recourse to the Medieval thinker John Duns Scotus and, on the other hand, by an adaptation to trends in contemporary scholasticism, first of all that of the Jesuits. What kind of metaphysics did this particular constellation within the history of philosophy produce? In order to answer this question, the present book analyses the work on metaphysics by the most important representative of early modern Scotism, Bartolomeo Mastri (1602-1673). In addition, the book investigates a multitude of scarcely or never studied works on metaphysics from the Franciscan scholastic tradition of the 17th and 18th centuries. The peculiar profile of a forgotten philosophical tradition with its astonishing plurality becomes apparent. By focusing on a phenomenon from the history of philosophy outside the mainstream, this work contributes to a more differentiated view on the intellectual culture in early modern Europe. (shrink)

This contribution builds on the idea of integrating truth-fulfilling entities into a truth-conditional semantics. It asks which kind of truth conditions are to be considered for statements of something being really there – as opposed to just being an intentional object. The adverbial theory of perception treats experiences, for example appearances (visual experiences), as ‘adverbially’ classified. As a further approach towards how an object is related to its appearance (being experienced visually), semantical externalism is considered. On this basis, it is (...) proposed that the notion of existence can be understood as a disposition to be experienced: y being really there is explicated as a disposition to experiences that are adverbially characterized as y-experiences. This approach helps to understand the different perspectives of the natural sciences and the arts and humanities. While the natural sciences are directed towards y, the arts and humanities primarily deal with y-experiences. (shrink)

The goal of this paper is to re-assess reflective equilibrium (“RE”). We ask whether there is a conception of RE that can be defended against the various objections that have been raised against RE in the literature. To answer this question, we provide a systematic overview of the main objections, and for each objection, we investigate why it looks plausible, on what standard or expectation it is based, how it can be answered and which features RE must have to meet (...) the objection. We find that there is a conception of RE that promises to withstand all objections. However, this conception has some features that may be unexpected: it aims at a justification that is tailored to understanding and it is neither tied to intuitions nor does it imply coherentism. We conclude by pointing out a cluster of questions we think RE theorists should pay more attention to. (shrink)

In this paper, we consider how certain longstanding philosophical questions about mental representation may be answered on the assumption that cognitive and perceptual systems implement hierarchical generative models, such as those discussed within the prediction error minimization framework. We build on existing treatments of representation via structural resemblance, such as those in Gładziejewski :559–582, 2016) and Gładziejewski and Miłkowski, to argue for a representationalist interpretation of the PEM framework. We further motivate the proposed approach to content by arguing that it (...) is consistent with approaches implicit in theories of unsupervised learning in neural networks. In the course of this discussion, we argue that the structural representation proposal, properly understood, has more in common with functional-role than with causal/informational or teleosemantic theories. In the remainder of the paper, we describe the PEM framework for approximate Bayesian inference in some detail, and discuss how structural representations might arise within the proposed Bayesian hierarchies. After explicating the notion of variational inference, we define a subjectively accessible measure of misrepresentation for hierarchical Bayesian networks by appeal to the Kullbach–Leibler divergence between posterior generative and approximate recognition densities, and discuss a related measure of objective misrepresentation in terms of correspondence with the facts. (shrink)

Originally presented as the author's thesis, Munich, 1972.

This book examines the theological methodology of Dutch theologian, Herman Bavinck (1854-1921). The focus of the book is on the influence of the German historicist movement on his theological method and uses Bavinck's doctrine of the Trinity as a way to test the argument that while not embracing all of the relativising implications of the movement, the role of history as a force that both shapes the present and allows for development into the future has a demonstrable influence on his (...) theological methodology. To make this argument the book considers Bavinck's larger nineteenth century context. It traces the development of both history and theology being understood as sciences in the university and how this required a reimagining of both disciplines. It could be said that the theology is thoroughly historicised in the nineteenth century. The book then considers the three principia of Bavinck's theological methodology: Revelation, Confession, and Christian Consciousness, demonstrating how Bavinck both appropriates and adapts historicist assumptions. (shrink)

This book deals with the role of international standards for corporate governance in the context of corporate social responsibility. Based on the fundamentals of moral theory, the book examines governance and CSR in general, addressing questions such as: Is "good governance" not affected by moral concerns? How do the principles and practices of CSR standards adhere to or conflict with insights from business ethics and moral theory? To what extent do the standards and governance models provide normative guidance? Do the (...) standards and governance guidelines provide an adequate means of benchmarking and auditing? Are these standards a help or a hindrance to stakeholder engagement and transparency? The book provides insightful and thought-provoking answers to these and many other important questions concerning CSR standards, and offers a valuable resource for practitioners, academics and students at business schools and other institutions. (shrink)

This paper is concerned with the processing of informal arguments, that is, arguments involving “probable truth.” A model of informal argument processing is presented that is based upon Hample's (1977) expansion of Toulmin's (1958) model of argument structure. The model postulates that a claim activates an attitude, the two components forming a complex that in turn activates reasons. Furthermore, the model holds occurrence of the reason, or possibly the claim and the reason, activates values. Three experiments are described that provide (...) support for the model. (shrink)

What is life? Is it just the biologically familiar--birds, trees, snails, people--or is it an infinitely complex set of patterns that a computer could simulate? What role does intelligence play in separating the organic from the inorganic, the living from the inert? Does life evolve along a predestined path, or does it suddenly emerge from what appeared lifeless and programmatic? In this easily accessible and wide-ranging survey, Claus Emmeche outlines many of the challenges and controversies involved in the dynamic (...) and curious science of artificial life. Emmeche describes the work being done by an international network of biologists, computer scientists, and physicists who are using computers to study life as it could be, or as it might evolve under conditions different from those on earth. Many artificial-life researchers believe that they can create new life in the computer by simulating the processes observed in traditional, biological life-forms. The flight of a flock of birds, for example, can be reproduced faithfully and in all its complexity by a relatively simple computer program that is designed to generate electronic "boids." Are these "boids" then alive? The central problem, Emmeche notes, lies in defining the salient differences between biological life and computer simulations of its processes. And yet, if we can breathe life into a computer, what might this mean for our other assumptions about what it means to be alive? The Garden in the Machine touches on every aspect of this complex and rapidly developing discipline, including its connections to artificial intelligence, chaos theory, computational theory, and studies of emergence. Drawing on the most current work in the field, this book is a major overview of artificial life. Professionals and nonscientists alike will find it an invaluable guide to concepts and technologies that may forever change our definition of life. (shrink)