We propose an interpretation of physics named potentiality realism. This view, which can be applied to classical as well as to quantum physics, regards potentialities (i.e. intrinsic, objective propensities for individual events to obtain) as elements of reality, thereby complementing the actual properties taken by physical variables. This allows one to naturally reconcile realism and fundamental indeterminism in any theoretical framework. We discuss our specific interpretation of propensities, that require them to depart from being probabilities at the formal level, though (...) allowing for statistics and the law of large numbers. This view helps reconcile classical and quantum physics by showing that most of the conceptual problems that are customarily taken to be unique issues of the latter -- such as the measurement problem -- are actually in common to all indeterministic physical theories. (shrink)

In this work, we focus on the philosophical aspects and technical challenges that underlie the axiomatization of the non-Kolmogorovian probability framework, in connection with the problem of quantum contextuality. This fundamental feature of quantum theory has received a lot of attention recently, given that it might be connected to the speed-up of quantum computers—a phenomenon that is not fully understood. Although this problem has been extensively studied in the physics community, there are still many philosophical questions that should be properly (...) formulated. We analyzed different problems from a conceptual standpoint using the non-Kolmogorovian probability approach as a technical tool. (shrink)

Over 40 years ago, I put forward a new philosophy of science based on the argument that physics, in only ever accepting unified theories, thereby makes a substantial metaphysical presupposition about the universe, to the effect it possesses an underlying unity. I argued that a new conception of scientific method is required to subject this problematic presupposition to critical attention so that it may be improved as science proceeds. This view has implications for the study of the metaphysics of science. (...) The view has however been ignored by recent contributions to the field. I indicate broader implications of the view, and consider reasons why the view has been neglected. (shrink)

Modern science began as natural philosophy, an admixture of philosophy and science. It was then killed off by Newton, as a result of his claim to have derived his law of gravitation from the phenomena by induction. But this post-Newtonian conception of science, which holds that theories are accepted on the basis of evidence, is untenable, as the long-standing insolubility of the problem of induction indicates. Persistent acceptance of unified theories only in physics, when endless equally empirically successful disunified rivals (...) are available, means that physics makes a persistent, problematic metaphysical assumption about the universe: that all disunified theories are false. This assumption, precisely because it is problematic, needs to be explicitly articulated within physics, so that it can be critically assessed and, we may hope, improved. The outcome is a new conception of science—aim-oriented empiricism—that puts science and philosophy together again, and amounts to a modern version of natural philosophy. Furthermore, aim-oriented empiricism leads to the solution to the problem of induction. Natural philosophy pursued within the methodological framework of aim-oriented empiricism is shown to meet standards of intellectual rigour that science without metaphysics cannot meet. (shrink)

Unlike almost all other philosophers of science, Karl Popper sought to contribute to natural philosophy or cosmology – a synthesis of science and philosophy. I consider his contributions to the philosophy of science and quantum theory in this light. There is, however, a paradox. Popper’s most famous contribution – his principle of demarcation – in driving a wedge between science and metaphysics, serves to undermine the very thing he professes to love: natural philosophy. I argue that Popper’s philosophy of science (...) is, in this respect, defective. Science cannot proceed without making highly problematic metaphysical assumptions concerning the comprehensibility and knowability of the universe. Precisely because these assumptions are problematic, rigour requires that they be subjected to sustained critical scrutiny, as an integral part of science itself. Popper’s principle of demarcation must be rejected. Metaphysics and philosophy of science become a vital part of science. Natural philosophy is reborn. A solution to the problem of what it means to say a theory is unified is proposed, a problem Popper failed to solve. In The Logic of Scientific Discovery, Popper made important contributions to the interpretation of quantum theory, especially in connection with Heisenberg's uncertainty relations. Popper's advocacy of natural philosophy has important implications for education. (shrink)

Are probabilism and special relativity compatible? Dieks argues that they are. But the possible universe he specifies, designed to exemplify both probabilism and special relativity, either incorporates a universal “now”, or amounts to a many world universe, or fails to have any one definite overall Minkowskian-type space-time structure. Probabilism and special relativity appear to be incompatible after all. What is at issue is not whether “the flow of time” can be reconciled with special relativity, but rather whether explicitly probabilistic versions (...) of quantum theory should be rejected because of incompatibility with special relativity. (shrink)

In order to tackle the question posed by the title – notoriously answered in the positive, among others, by Heisenberg, Margenau, Popper and Redhead – I first discuss some attempts at distinguishing dispositional from non-dispositional properties, and then relate the distinction to the formalism of quantum mechanics. Since any answer to the question titling the paper must be interpretation-dependent, I review some of the main interpretations of quantum mechanics in order to argue that the ontology of theories regarding “wave collapse” (...) as a genuine physical process could be interpreted as being irreducibly dispositional. In non-collapse interpretations, on the contrary, the appeal to dispositions is simply a way to reformulate the predictive content of the algorithm of the theory in a fancier metaphysical language. (shrink)

As common experience confirms, procrastination seems not only possible, but widespread. However, procrastination should not be taken for granted. Often, the procrastinator harms herself knowingly. It thus clearly seems that such a person lacks the self-concern that usually characterises us. After having spelled out what procrastination is, and having explored its main varieties, I consider the relation between procrastination and risk-taking. After this, I discuss the implications of this phenomenon for the debates about personal identity. The upshot, I argue, is (...) that reductionist accounts, according to which identity is a matter of psychological continuity, are in a better position as might have been thought. (shrink)

Incommensurability was Kuhn’s worst mistake. If it is to be found anywhere in science, it would be in physics. But revolutions in theoretical physics all embody theoretical unification. Far from obliterating the idea that there is a persisting theoretical idea in physics, revolutions do just the opposite: they all actually exemplify the persisting idea of underlying unity. Furthermore, persistent acceptance of unifying theories in physics when empirically more successful disunified rivals can always be concocted means that physics makes a persistent (...) implicit assumption concerning unity. To put it in Kuhnian terms, underlying unity is a paradigm for paradigms. We need a conception of science which represents problematic assumptions concerning the physical comprehensibility and knowability of the universe in the form of a hierarchy, these assumptions becoming less and less substantial and more and more such that their truth is required for science, or the pursuit of knowledge, to be possible at all, as one goes up the hierarchy. This hierarchical conception of science has important Kuhnian features, but also differs dramatically from the view Kuhn expounds in his The Structure of Scientific Revolutions. In this paper, I compare and contrast these two views in a much more detailed way than has been done hitherto. I show how the hierarchical view can be construed to emerge from Kuhn’s view as it is modified to overcome objections. I argue that the hierarchical conception of science is to be preferred to Kuhn’s view. (shrink)

Karl Popper is famous for having proposed that science advances by a process of conjecture and refutation. He is also famous for defending the open society against what he saw as its arch enemies – Plato and Marx. Popper’s contributions to thought are of profound importance, but they are not the last word on the subject. They need to be improved. My concern in this book is to spell out what is of greatest importance in Popper’s work, what its failings (...) are, how it needs to be improved to overcome these failings, and what implications emerge as a result. The book consists of a collection of essays which dramatically develop Karl Popper’s views about natural and social science, and how we should go about trying to solve social problems. Criticism of Popper’s falsificationist philosophy of natural science leads to a conception of science that I call aim-oriented empiricism. This makes explicit metaphysical theses concerning the comprehensibility and knowability of the universe that are an implicit part of scientific knowledge – implicit in the way science excludes all theories that are not explanatory, even those that are more successful empirically than accepted theories. Aim-oriented empiricism has major implications, not just for the academic discipline of philosophy of science, but for science itself. Popper generalized his philosophy of science of falsificationism to arrive at a new conception of rationality – critical rationalism – the key methodological idea of Popper’s profound critical exploration of political and social issues in his The Open Society and Its Enemies, and The Poverty of Historicism. This path of Popper, from scientific method to rationality and social and political issues is followed here, but the starting point is aim-oriented empiricism rather than falsificationism. Aim-oriented empiricism is generalized to form a conception of rationality I call aim-oriented rationalism. This has far-reaching implications for political and social issues, for the nature of social inquiry and the humanities, and indeed for academic inquiry as a whole. The strategies for tackling social problems that arise from aim-oriented rationalism improve on Popper’s recommended strategies of piecemeal social engineering and critical rationalism, associated with Popper’s conception of the open society. This book thus sets out to develop Popper’s philosophy in new and fruitful directions. The theme of the book, in short, is to discover what can be learned from scientific progress about how to achieve social progress towards a better world. (shrink)

In this article I reply to comments made by Agustin Vicente and Giridhari Lal Pandit on Science and the Pursuit of Wisdom (McHenry 2009 ). I criticize analytic philosophy, go on to expound the argument for the need for a revolution in academic inquiry so that the basic aim becomes wisdom and not just knowledge, defend aim-oriented empiricism, outline my solution to the human world/physical universe problem, and defend the thesis that free will is compatible with physicalism.

In this paper I argue that aim-oriented empiricism provides decisive grounds for accepting scientific realism and rejecting instrumentalism. But it goes further than this. Aim-oriented empiricism implies that physicalism is a central part of current (conjectural) scientific knowledge. Furthermore, we can and need, I argue, to interpret fundamental physical theories as attributing necessitating physical properties to fundamental physical entities.

In this paper I show that Einstein made essential use of aim-oriented empiricism in scientific practice in developing special and general relativity. I conclude by considering to what extent Einstein came explicitly to advocate aim-oriented empiricism in his later years.

In a recent paper, Howard Stein makes a number of criticisms of an earlier paper of mine ('Are Probabilism and Special Relativity Incompatible?', Phil. Sci., 1985), which explored the question of whether the idea that the future is genuinely 'open' in a probabilistic universe is compatible with special relativity. I disagree with almost all of Stein's criticisms.

The objective of this paper is to show that, instead of quantum probabilities, wave packets are physically real. First, Cartwright's recent argument for the reality of quantum probabilities is criticized. Then, the notion of ‘physically real’ is precisely defined and the difference between wave functions and quantum probabilities clarified. Being thus prepared, some strong reasons are discussed for considering the wave packet to be physically real. Finding the reasons inconclusive, I explain how the Aharonov—Bohm effect delivers the final punch. I (...) conclude that wave packets are the quantum objects that underlie the indeterministic quantum processes and have the propensity of displaying probabilistic (or indeterministic) behavior. (shrink)

My title is intended to recall Terence Fine's excellent survey, Theories of Probability [1973]. I shall consider some developments that have occurred in the intervening years, and try to place some of the theories he discussed in what is now a slightly longer perspective. Completeness is not something one can reasonably hope to achieve in a journal article, and any selection is bound to reflect a view of what is salient. In a subject as prone to dispute as this, there (...) will inevitably be many who will disagree with any author's views, and I take the opportunity to apologize in advance to all such people for what they will see as the narrowness and distortion of mine. (shrink)

It is shown how the development of physics has involved making explicit what were homocentric projections which had heretofore been implicit, indeed inexpressible in theory. This is shown to support a particular notion of the invariant as the real. On this basis the divergence in ideals of physical intelligibility between Bohr and Einstein is set out. This in turn leads to divergent, but explicit, conceptions of objectivity and completeness for physical theory. *I am indebted to Dr. G. McLelland. Professor F. (...) Rohrlich and an anonymous referee of this journal for several improvements in the formulation of the paper. (shrink)

I review five explicit attempts throughout the history of quantum mechanics to invoke dispositional notions in order to solve the quantum paradoxes, namely: Margenau’s latencies, Heisenberg’s potentialities, Popper’s propensity interpretation of probability, Nick Maxwell’s propensitons, and the recent selective propensities interpretation of quantum mechanics. I raise difficulties and challenges for all of them, but conclude that the selective propensities approach nicely encompasses the virtues of its predecessors. I elaborate on some of the properties of the type of propensities that I (...) claim to be successful for quantum mechanics, and finish by briefly sketching out ways in which similar notions can be read into some of the other well-known interpretations of quantum mechanics. (shrink)

We may suspect that quantum mechanics and consciousness are related, but the details are not at all clear. In this paper, I suggest how the mind and brain might fit together intimately while still maintaining distinct identities. The connection is based on the correspondence of similar functions in both the mind and the quantum-mechanical brain. Accompanying material for a talk at The Second Mind and Brain Symposium held at the Institute of Psychiatry, Denmark Hill, London on 20th October, 1990.

For nearly six decades, the conscious observer has played a central and essential rôle in quantum measurement theory. I outline some difficulties which the traditional account of measurement presents for material theories of mind before introducing a new development which promises to exorcise the ghost of consciousness from physics and relieve the cognitive scientist of the burden of explaining why certain material structures reduce wavefunctions by virtue of being conscious while others do not. The interactive decoherence of complex quantum systems (...) reveals that the oddities and complexities of linear superposition and state vector reduction are irrelevant to computational aspects of the philosophy of mind and that many conclusions in related fields are ill founded. (shrink)

In this paper we provide a general account of the causal models which attempt to provide a solution to the famous measurement problem of Quantum Mechanics. We will argue that—leaving aside instrumentalism which restricts the physical meaning of QM to the algorithmic prediction of measurement outcomes—the many interpretations which can be found in the literature can be distinguished through the way they model the measurement process, either in terms of the efficient cause or in terms of the final cause. We (...) will discuss and analyze why both, ‘final cause’ and ‘efficient cause’ models, face severe difficulties to solve the measurement problem. In contradistinction to these schemes we will present a new model based on the immanent cause which, we will argue, provides an intuitive understanding of the measurement process in QM. (shrink)

This paper reviews four attempts throughout the history of quantum mechanics to explicitly employ dispositional notions in order to solve the quantum paradoxes, namely: Margenau's latencies, Heisenberg's potentialities, Maxwell's propensitons, and the recent selective propensities interpretation of quantum mechanics. Difficulties and challenges are raised for all of them, and it is concluded that the selective propensities approach nicely encompasses the virtues of its predecessors. Finally, some strategies are discussed for reading similar dispositional notions into two other well-known interpretations of quantum (...) mechanics, namely the GRW interpretation and Bohmian mechanics. (shrink)

In this paper we compare two different notions of 'power', both of which attempt to provide a realist understanding of quantum mechanics grounded on the potential mode of existence. For this propose we will begin by introducing two different notions of potentiality present already within Aristotelian metaphysics, namely, irrational potentiality and rational potentiality. After discussing the role played by potentiality within classical and quantum mechanics, we will address the notion of causal power which is directly related to irrational potentiality and (...) has been adopted by many interpretations of QM. We will then present the notion of immanent power which relates to rational potentiality and argue that this new concept presents important advantages regarding the possibilities it provides for understanding in a novel manner the theory of quanta. We end our paper with a comparison between both notions of 'power', stressing some radical differences between them. (shrink)

In 2002 the readers of the scientific magazine 'Physics World' voted Young's double-slit experiment applied to the interference of single electrons to be 'the most beautiful experiment in physics'; this experiment, in truth, had already been carried out 30 years beforehand. The present article aims to re-examine the latter real experiment and put it into its proper historical perspective. Even though the experiment was not afforded the importance it perhaps deserved among philosophers, its philosophical mplications add new arguments to the (...) already far-reaching debate triggered off by the ideal experiment. Within the context of quantum mechanics in particular, the experiment revealed for the first time the importance that ought to be attributed at the empirical level to single-case probability, that is, to the probability of a single electron's reaching the screen. I investigate how the empirical significance of the experimental results comes within the framework of the debate over the propensity interpretation of probability in quantum mechanics. I argue that the experiment, when examined in all its technical details does in fact throw light on the evidence for the propensity, as a physical property, of micro-objects. (shrink)

A prominent way through which wave-particle duality has been ascribed to photons is by illustrating their “wave-like” behaviour in the Mach-Zehnder interferometer and “particle-like” behaviour in the anti-correlation experiment. This duality has been formulated in two ways. Some have based the claim on the complementarity principle. This formulation, however, has already been shown to be problematic. Others have made a much simpler duality claim by considering that single-photons are analogous to waves and particles in the above experiments. I criticise this (...) formulation by arguing that the analogies cannot be distinctly established. Thus, this duality claim is found to be unsubstantiated. (shrink)

Examining the role of dispositions (potentials and propensities) in both physics and psychology reveals that they are commonly derivative dispositions, so called because they derive from other dispositions. Furthermore, when they act, they produce further propensities. Together, therefore, they appear to form discrete degrees within a structure of multiple generative levels. It is then constructively hypothesized that minds and physical nature are themselves discrete degrees within some more universal structure. This gives rise to an effective dualism of mind and nature, (...) but one according to which they are still constantly related by causal connections. I suggest a few of the unified principles of operation of this more complicated but universal structure. (shrink)

The following analysis attempts to provide a general account of the multiple solutions given to the quantum measurement problem in terms of causality. Leaving aside instrumentalism which restricts its understanding of quantum mechanics to the algorithmic prediction of measurement outcomes, the many approaches which try to give an answer can be distinguished by their explanation based on the efficient cause —recovering in this way a classical physical description— or based on the final cause —which goes back to the hylomorphic tradition. (...) Going beyond the limits of these two schemes we call the attention to an ‘inversion of the measurement problem’ and its proposed solution based on the immanent cause. By replacing both the final and efficient causes by the immanent cause we attempt to lay down new conditions for representing quantum superpositions in a realist way which coherently relates the quantum formalism with outcomes. (shrink)