This book examines a selection of philosophical issues in the context of specific episodes in the development of physical theories. Advances in science are presented against the historical and philosophical backgrounds in which they occurred. A major aim is to impress upon the reader the essential role that philosophical considerations have played in the actual practice of science. The book begins with some necessary introduction to the history of ancient and early modern science, with major emphasis being given to the (...) two great watersheds of twentieth-century physics: relativity and, especially, quantum mechanics. At times the term 'construction' may seem more appropriate than 'discovery' for the way theories have developed and, especially in the later chapters, the question of the influence of historical, philosophical and even social factors on the very form and content of scientific theories is discussed. (shrink)
We are often told that quantum phenomena demand radical revisions of our scientific world view and that no physical theory describing well defined objects, such as particles described by their positions, evolving in a well defined way, let alone deterministically, can account for such phenomena. The great majority of physicists continue to subscribe to this view, despite the fact that just such a deterministic theory, accounting for all of the phe nomena of nonrelativistic quantum mechanics, was proposed by David Bohm (...) more than four decades ago and has arguably been around almost since the inception of quantum mechanics itself. Our purpose in asking colleagues to write the essays for this volume has not been to produce a Festschrift in honor of David Bohm or to gather together a collection of papers simply stating uncritically Bohm's views on quantum mechanics. The central theme around which the essays in this volume are arranged is David Bohm's version of quantum mechanics. It has by now become fairly standard practice to refer to his theory as Bohmian mechanics and to the larger conceptual framework within which this is located as the causal quantum theory program. While it is true that one can have reservations about the appropriateness of these specific labels, both do elicit distinc tive images characteristic of the key concepts of these approaches and such terminology does serve effectively to contrast this class of theories with more standard formulations of quantum theory. (shrink)
One of the major philosophical problems in physical sciences is what criteria should determine how scientific theories are selected and justified in practice and whether, in describing observable physical phenomena, such theories are effectively constrained to be unique. This book studies the example of a particular theory, the S-matrix theory. The S-matrix program was initiated by Heisenberg to deal with difficulties encountered in quantum field theories in describing particular phenomena. Since then, each theory has at different times been favored as (...) the explanation of observed phenomena. Certainly the S-matrix theory was adequate, feasible and fertile. However, the quantum field theory interpretation is now widely accepted and the study of alternative theories is all but abandoned. By examining the philosophy which influenced the turns in this story, the author explains how an adequate and viable theory fell out of favor and concludes with a critique of different methodologies in the history of science. (shrink)
Empirical adequacy, formal explanation and understanding are distinct goals of science. While no a priori criterion for understanding should be laid down, there may be inherent limitations on the way we are able to understand explanations of physical phenomena. I examine several recent contributions to the exercise of fashioning an explanatory discourse to mold the formal explanation provided by quantum mechanics to our modes of understanding. The question is whether we are capable of truly understanding (or comprehending) quantum phenomena, as (...) opposed to simply accepting the formalism and certain irreducible quantum correlations. The central issue is that of understanding versus merely redefining terms to paper over our ignorance. (shrink)
A case study of the development of quantum field theory and of S-matrix theory, from their inceptions to the present, is presented. The descriptions of science given by Kuhn and by Lakatos are compared and contrasted as they apply to this case study. The episodes of the developments of these theories are then considered as candidates for competing research programs in Lakatos' methodology of scientific research programs. Lakatos' scheme provides a reasonable overall description and a plausible assessment of the relative (...) value of these two programs in terms of progressive and degenerating problem shifts. Also discussed are the roles of various types of models as they have been used in these areas of theoretical high-energy physics. (shrink)
The ubiquity of chaos in classical mechanics (CM), as opposed to the situation in standard quantum mechanics (QM), might be taken as speaking against QM being the fundamental theory of physical phenomena. Bohmian mechanics (BM), as a formulation of quantum theory, may clarify both the existence of chaos in the quantum domain and the nature of the classical limit. Two interesting possibilities are (i) that CM and classical chaos are included in and underwritten by quantum mechanics (BM) or (ii) that (...) BM and CM simply possess a common region of (noninclusive) overlap. In the latter case, neither CM nor QM alone would be sufficient, even in principle, to account for all of the physical phenomena we encounter. In this talk I shall summarize and discuss the implications of some recent work on chaos and on the classical limit within the framework of BM. (shrink)
It is generally believed that Bohm's version of quantum mechanics is observationally equivalent to standard quantum mechanics. A more careful statement is that the two theories will always make the same predictions for any question or problem that is well posed in both interpretations. The transit time of a “particle” between two points in space is not necessarily well defined in standard quantum mechanics, whereas it is in Bohm's theory since there is always a particle following a definite trajectory. For (...) this reason tunneling times (in a scattering configuration through a potential barrier may be a situation in which Bohm's theory can make a definite prediction when standard quantum mechanics can make none at all. I summarize some of the theoretical and experimental prospects for an unambiguous comparison in the hope that this question will engage the attention of more physicists, especially those experimentalists who now routinely actually do gedanken experiments. (shrink)
This paper is a critique of a project, outlined by Laudan et al. (1986) recently in this journal, for empirically testing philosophical models of change in science by comparing them against the historical record of actual scientific practice. While the basic idea of testing such models of change in the arena of science is itself an appealing one, serious questions can be raised about the suitability of seeking confirmation or disconfirmation for large numbers of specific theses drawn from a massive (...) list of claims abstracted from the writings of a few philosophers of science. The present paper discusses what one might reasonably expect from a model of change in science and then compares some clusters of theses from Laudan et al. with developments in recent theoretical physics. The results suggest that such straightforward testing of theses may be largely inconclusive. (shrink)
Any division between scientific practice and a metalevel of the methods and goals of science is largely a false dichotomy. Since a priori, foundationist or logicist approaches to normative principles have proven unequal to the task of representing actual scientific practice, methodologies of science must be abstracted from episodes in the history of science. Of course, it is possible that such characteristics could prove universal and constant across various eras. But, case studies show that they are not in anything beyond (...) the strictures applied to everyday, commonsense reasoning (e.g., a requirement of noncontradiction in a deductive argument). Hence, even if some presently-on-offer methodology or description of past scientific practice were adequate, it need not remain so for current (‘frontier’) areas of science. For this reason, it is important to examine recent episodes in, say, high-energy physics. Results from case studies of several episodes in that field are used to argue that successful practice leads scientists to countenance essential changes in the methodological framework at the levels of the criteria employed in judging theories (i.e., what counts for an explanation and what are canons of rationality) and of the goals of science. *Partial support for this research was provided by the History and Philosophy of Science Program of the National Science Foundation under grants Nos. SES-8606472 and SES-8705469. A preliminary version of this paper was given at an HPS seminar at King's College, London University in May 1988. Helpful comments and useful criticisms were made by several colleagues, especially Ernan McMullin, Heinz Post and Simon Saunders (none of whom are to be held responsible for or necessarily even in agreement with the views expressed here.). (shrink)
In the philosophy of science, we are to assess critically and on their intrinsic merits various proposals for a consistent interpretation of quantum mechanics, including resolutions of the measurement problem and accounts of the long-range Bell correlations. In this paper I suggest that the terms of debate may have been so severely and unduly constrained by the reigning orthodoxy that we labor unproductively with an unhelpful vocabulary and set of definitions and distinctions. I present an alternative conceptual framework, free of (...) many of the standard conundrums. (shrink)
I argue that historical contingency, in the sense of the order in which events take place, can be an essential factor in determining which of two equally adequate and fruitful, but observationally indistinguishable, scientific theories is accepted by the scientific community. This type of actual underdetermination poses questions for scientific realism and for rational reconstruction in theory evaluation. To illustrate this, I discuss the complete observational equivalence of two radically different, conceptually incompatible interpretations of quantum mechanics and argue that an (...) entirely plausible reordering of historical factors could reasonably have resulted in the causal program having been chosen over the "Copenhagen" one. (shrink)
Many factors are operative in the scientific enterprise to provide the epistemic warrant which finally convinces people to accept a scientific theory. The methods, goals and meanings of terms do not remain fixed, but evolve over time. This paper concentrates on one aspect of this shifting pattern of scientific practice - the role and meaning of causality in modern physics.
Examples of theory development in quantum field theory and in S-matrix theory are related to three questions of interest to the philosophy of science. The first is the central role of highly abstract, mathematical models in the creation of theories. Second, the process of creation and justification actually used make it plausible that a successful theory is equally well characterized as being stable against attack rather than as being objectively correct. Lastly, the issue of the reality of theoretical entities is (...) discussed in light of this representation of theory generation and selection. (shrink)
Examples, mainly from research in current physics, are used to examine and illustrate the network of factors which produce in scientific debate a convergence of opinion to a generally accepted set of laws and theories. Also addressed is the question of the reliability of these general theories as a faithful representation of the complexity of physical reality.