Roger Penrose's original and provocative ideas about the large-scale physics of the Universe, the small-scale world of quantum physics and the physics of the mind have been the subject of controversy and discussion. These ideas were set forth in his best-selling books The Emperor's New Mind and Shadows of the Mind. In this book, he summarises and brings up to date his current thinking in these complex areas. He presents a masterful summary of those areas of physics in which he (...) feels there are major unsolved problems. Through this, he introduces radically new concepts which he believes will be fruitful in understanding the workings of the brain and the nature of the human mind. These ideas are then challenged by three distinguished experts from different backgrounds - Abner Shimony and Nancy Cartwright as Philosophers of Science and Stephen Hawking as a Theoretical Physicist and Cosmologist. Finally, Roger Penrose responds to their thought-provoking criticisms. This volume provides an accessible, illuminating and stimulating introduction to Roger Penrose's vision of theoretical physics for the 21st Century. His enthusiasm, insight and good humour shine through this brilliant account of the problems of modern physics. (shrink)

Commonplace things such as hawks and handsaws pose philosophical problems at least as imposing as those presented by abstract objects such as numbers and divine beings. Van Inwagen's metaphysic of material beings emerges from what he perceives to be the proper answer to the Special Composition Question, which is, roughly, the following: Under what conditions do various things compose a single thing? The first eight sections of the book address and dismiss various extreme and moderate proposals for resolving this question. (...) Van Inwagen argues vigorously for the view that our world contains, aside from mereologically "simple" entities, only living organisms, the activity of whose various parts constitutes a life. Strictly speaking, there are no tables, chairs, ships, or handsaws. A handsaw is merely a "virtual" and not a genuine object, whereas my cat is a genuine and not merely a virtual object. Felines and humans and other macroscopic individuals are composed of various cells, which themselves are composed of simples, whereas the nonentity that is my bicycle is merely virtually composed of various macroscopic and microscopic virtual objects. Van Inwagen argues that none of this contradicts our ordinary beliefs about the world we inhabit. Although there are, strictly speaking, no inanimate objects other than simples, there are various simples that are arranged bicycle-wise and still other simples arranged ship-wise. It is a corollary of van Inwagen's answer to the Special Composition Question that such simples compose nothing. Since there is nothing such simples compose, there really are no such things as bicycles and ships. Artisans do not create in the sense of causing things to exist, but only rearrange simples in ship-like and table-like ways. The situation is different when we consider biological conception and the emergence of a human life. In this case, but not in artifact cases, a new individual arrives on the cosmic stage. Van Inwagen argues that conception leaves us with "a new individual" which itself perishes when it divides. You were never a zygote, since you presently exist, although your zygote--the zygote from which you developed--does not. It is argued that lives are "infected with vagueness at both ends." In various borderline cases, there are simples such that there is simply no correct yes or no answer to the question, Does the activity of these simples constitute a life? Accordingly there is no determinate answer to the question, Do these simples compose something? Van Inwagen argues against the Linguistic Theory of Vagueness and offers a detailed defense of the vagueness of identity. In cases of vague diachronic identity, there is a sense in which the transitivity of identity principle fails. Starting with premises that are half-truths, this principle may in certain cases license a false conclusion. (shrink)

An analogue of Hawking's black hole area theorem is proved for Friedmann-type cosmological models with event horizons. The generalised second law of thermodynamics is investigated in cases where the horizon shrinks.

The oft-neglected issue of the causal structure in the flat spacetime approach to Einstein's theory of gravity is considered. Consistency requires that the flat metric's null cone be respected, but this does not automatically happen. After reviewing the history of this problem, we introduce a generalized eigenvector formalism to give a kinematic description of the relation between the two null cones, based on the Segre' classification of symmetric rank 2 tensors with respect to a Lorentzian metric. Then we propose a (...) method to enforce special relativistic causality by using the gauge freedom to restrict the configuration space suitably. A set of new variables just covers this smaller configuration space and respects the flat metric's null cone automatically. Respecting the flat metric's null cone ensures that the spacetime is globally hyperbolic, indicating that the Hawking black hole information loss paradox does not arise in the special relativistic approach to Einstein's theory. (shrink)

On the theory of meaning and reference (semantics) as interpretated by W.V. Quine; a study.

The plan for this volume emerged during the international Leipzig conference commemorating the centenary of the death of Gustav Fechner.