Online research in philosophy

This conference was devoted to the 80 years of the Copenhagen Interpretation, and to the question of the relevance of the Copenhagen interpretation for the present understanding of quantum mechanics. It is in this framework that fundamental questions raised by quantum mechanics, especially in information theory, were discussed throughout the conference. As has become customary in our series of conference in Växjö, we were glad to welcome a fruitful assembly of theoretical physicists, experimentalists, mathematicians and even philosophers interested in the foundations of probability and physics. The nature of quantum fluctuations---in the form of Stochastic Electrodynamics or in other approaches to stochastic quantum mechanics---was also a central topic discussed during the conference, especially during debates. We should also mention talks on the completeness or incompleteness of quantum mechanics; on macroscopic quantum systems; on Bell's inequality, entanglement and experiments on quantum nonlocality (and locality); on Bohmian mechanics; on the connection between quantum mechanics and general relativity; on quantum probability; on quantum computing, quantum teleportation and quantum cryptography technologies; and more generally on the mathematical formalism of quantum mechanics and on the philosophical problems raised by its interpretations.

Quantum mechanics is usually presented as a challenge to scientific realism, but I will argue that the details of quantum mechanics actually support realism. I will first present some basic quantum mechanical concepts and results, including the Einstein-Podolsky-Rosen (EPR) experiment and Bell's theorem, and do it in a way that everyone can understand. I will then use the physics to inform the philosophy, showing that quantum mechanics provides evidence to support epistemological realism.

Abstract Quantum mechanics has seemed to defy all attempts to construe it realistically, but antirealism, like the many?worlds hypothesis, is even more difficult to accept. In order to give a realist construal of quantum mechanics, we need first to distinguish the objective and rational aspect of reality from the paradigmatic thing?like aspects of having determinate physical properties: quantum?mechanical entities may be real in the former sense though not in the latter. Anti?realist arguments are based on the difficulty of giving an account of quantum?mechanical collapse and the apparent superluminal velocities involved. Objections to superluminal velocities on the score of the special theory of relativity are found not to be conclusive, and the price?there being some preferred frame of reference?to be acceptable. A sketch of a probabilistic account of quantum?mechanical collapse is offered, which makes the difference between the macro? and the micro?world a matter of degree rather than kind. If that, or some other, account proved acceptable, we could be quantum?mechanical realists, though quantum?mechanical reality would be very different from that of material objects in hardware shops.

Quantum theory is a tremendously successful physical theory, but nevertheless suffers from two serious problems: the measurement problem and the problem of interpretational underdetermination. The latter, however, is largely overlooked as a genuine problem of its own. Both problems concern the doctrine of realism, but pull, quite curiously, into opposite directions. The measurement problem can be captured such that due to scientific realism about quantum theory common sense anti-realism follows, while theory underdetermination usually counts as an argument against scientific realism. I will also consider the more refined distinctions of ontic and epistemic realism and demonstrate that quantum theory in its most viable interpretations conflicts with at least one of the various realism claims. A way out of the conundrum is to come to the bold conclusion that quantum theory is, possibly, wrong (in the realist sense).

Confused ideas about the weirdness of quantum mechanics have sometimes been blamed for the spread of anti-realist positions in philosophy. In this seminar, I shall re-examine the relation between realism and quantum theory. My goal is to argue that one can remain a realist in a reasonably familiar sense, while adopting a theory which amounts to a form of idealism. After sketching the abstract mathematical structure of quantum theory, I will introduce realism and consider some of its problems and some counter-arguments. Next I will look at why quantum theory needs an interpretation and at some of the features common to many proposed interpretations. Then I will discuss some of the gaps in decoherence theory, when it is considered as an interpretation of quantum theory, and I will end with a sketch of my own realist version of idealism in which the fundamental entities are structures which define minds, and the fundamental laws govern the stochastic developments of those structures.

The interpretation of quantum mechanics has always been a pain in the backside of scientific realism. Throughout its history, various anti-realist doctrines have dominated, associated with such luminaries as Niels Bohr and Werner Heisenberg, and referred to collectively as ‘the Copenhagen interpretation’. The voice of realist dissent was thus marginalized, but never silenced. In recent years, renewed interest has attached to the possibility of a realist interpretation of quantum theory. Christopher Norris’ book is an effort in this tradition.

The de Broglie-Bohm interpretation of quantum mechanics (BM) has been favored as the preferred alternative to standard quantum mechanics on the ground that it allows a realist construal of the quantum world. We examine in the present work whether BM is consistent with scientific realism. Indeed, Bohmian mechanics makes strong ontological claims but accepts in principle the impossibility of generating epistemic warrants in support of its assumptions. We will argue that such a situation gives rise, at best, to an unsolvable underdetermination dilemma. This leads in turn to the following paradox: although Bohmian mechanics has frequently been invoked to reconcile quantum mechanics with realism, its status as a valid interpretation of quantum mechanics hinges nonetheless on nonevidential epistemological arguments traditionally associated with antirealism.

Quantum Theory and the Flight from Realism is a critical introduction to the long-standing debate concerning the conceptual foundations of quantum mechanics, and the problems it has posed for physicists and philosophers from Einstein to the present. Quantum theory has been a major influence on postmodernism, and presents significant challenges for realists. Clarifying these debates for the non-specialist, Christopher Norris examines the premises of orthodox quantum theory and its impact on various philosophical developments. He subjects a wide range of opponents and supporters of realism to a high and equal level of scrutiny. Combining rigor and intellectual generosity, he draws out the merits and weaknesses from opposing arguments.

In this essay, I offer a critical evaluation of Hilary Putnam's writings on epistemology and philosophy of science, in particular his engagement with interpretative problems in quantum mechanics. I trace the development of his thinking from the late 1960s when he adopted a strong causal-realist position on issues of meaning, reference, and truth, via the "internal realist" approach of his middle-period writings, to the various forms of pragmatist, naturalized, or "commonsense" epistemology proposed in his latest books. My contention is that Putnam's retreat from a full-fledged realist outlook has been prompted in large part by his belief that it cannot possibly be reconciled with the implications of quantum mechanics for our understanding of processes and events in the subatomic domain. However, I suggest, this response should be seen as premature given the range of as-yet unresolved problems with quantum mechanics on the orthodox (Copenhagen) interpretation and also the existence of an alternative account - David Bohm's hidden-variables theory - which perfectly matches the established predictive-observational results while providing a credible realist ontology. I also examine Putnam's case for adopting a nonstandard (three-valued) "quantum logic" in relation to the thinking of other philosophers - Michael Dummett among them - who have espoused a more global or doctrinaire version of anti-realism. I conclude that Putnam's early (causal-realist) position is by no means untenable in light of the various arguments that he now takes as counting decisively against it.

EPR experiments demonstrate that standard quantum mechanics exhibits the property of nonlocality , the enforcement of correlations between separated parts of an entangled quantum systems across spacelike separations. Nonlocality will be clarified using the transactional interpretation of quantum mechanics, and the possibility of superluminal effects (e.g., faster-than-light communication) from nonlocality and non-linear quantum mechanics will be examined.