This paper proposes a classification of the intertheoretic relations in physics by bringing out the conditions for a relation of reduction which is eliminative, so that a theory reduced in terms of reductionism is superfluous in principle, and by distinguishing such a relation from another one based on comparison, which will be called neighbourhood of theories; the latter is a neighbouring relation between theories and is not able to support claims of eliminative reductionism. In the first part, it will be (...) argued that this differentiation between neighbourhood and eliminative reduction permits an adequate classification of the intertheoretic relations in physics. By means of this differentiation, the second part discusses reductionism and shows that there are indeed some historical examples of reduction in the aforementioned sense, but that modern physical theories are typically only neighbouring. (shrink)

I interpret the philosophical views of Werner Heisenberg as a pragmatism and non-metaphysical realism of a Wittgensteinian kind. The “closed theory” is a Wittgensteinian rule/concept.

We begin by highlighting some points related to Kuhn’s later thoughts on the incommensurability thesis and then show to what extent the standard version of the thesis given by the structuralist metatheory allows us to capture Kuhn’s ideas. Our main aim is to establish what constitutes the basis of comparability between incommensurable theories, even in cases of incommensurability with respect to theoretical and non-theoretical terms. We propose that comparability between incommensurable theories requires some connection between their respective ontologies that can (...) be captured by means of an ontological non-reductive relation. At this point, the structuralist notion of “echeloned partial substructure” may be of help. When the incommensurability is very drastic, the existence of ontological connections between the theories involved may only be evident by common terms of their non-characteristic vocabularies. So, this notion of non-characteristic vocabulary becomes relevant in our proposal. (shrink)

The relationship between classical and quantum theory is of central importance to the philosophy of physics, and any interpretation of quantum mechanics has to clarify it. Our discussion of this relationship is partly historical and conceptual, but mostly technical and mathematically rigorous, including over 500 references. For example, we sketch how certain intuitive ideas of the founders of quantum theory have fared in the light of current mathematical knowledge. One such idea that has certainly stood the test of time is (...) Heisenberg's `quantum-theoretical Umdeutung (reinterpretation) of classical observables', which lies at the basis of quantization theory. Similarly, Bohr's correspondence principle (in somewhat revised form) and Schroedinger's wave packets (or coherent states) continue to be of great importance in understanding classical behaviour from quantum mechanics. On the other hand, no consensus has been reached on the Copenhagen Interpretation, but in view of the parodies of it one typically finds in the literature we describe it in detail. On the assumption that quantum mechanics is universal and complete, we discuss three ways in which classical physics has so far been believed to emerge from quantum physics, namely in the limit h -> 0 of small Planck's constant (in a finite system), in the limit N goes to infinity of a large system with $N$ degrees of freedom (at fixed h), and through decoherence and consistent histories. The first limit is closely related to modern quantization theory and microlocal analysis, whereas the second involves methods of C*-algebras and the concepts of superselection sectors and macroscopic observables. In these limits, the classical world does not emerge as a sharply defined objective reality, but rather as an approximate appearance relative to certain ``classical" states and observables. Decoherence subsequently clarifies the role of such states, in that they are ``einselected", i.e. robust against coupling to the environment. Furthermore, the nature of classical observables is elucidated by the fact that they typically define (approximately) consistent sets of histories. This combination of ideas and techniques does not quite resolve the measurement problem, but it does make the point that classicality results from the elimination of certain states and observables from quantum theory. Thus the classical world is not created by observation (as Heisenberg once claimed), but rather by the lack of it. (shrink)

Nous interprétons les vues philosophiques de Werner Heisenberg comme un pragmatisme et un réalisme non-métaphysique de type Wittgensteinien. La « théorie close » est une règle (concept) Wittgensteinienne. À la différence d’Alisa Bokulich qui donne raison à la position de Paul Dirac sur la nature des relations entre les théories physiques différentes, nous favorisons plutôt celle de Heisenberg. Notre position interprétant Heisenberg va aussi à l’encontre de celle de Popper: le critère d’une théorie scientifique établie (close) est sa non-falsifiabilité. -/- (...) . (shrink)

In this paper, I analyze the extent to which classical phase transitions, especially continuous phase transitions, impose a challenge for reduction- ism. My main contention is that classical phase transitions are compatible with reduction, at least with the notion of limiting reduction, which re- lates the behavior of physical quantities in different theories under certain limiting conditions. I argue that this conclusion follows even after rec- ognizing the existence of two infinite limits involved in the treatment of continuous phase transitions.

Reduction and reductionism have been central philosophical topics in analytic philosophy of science for more than six decades. Together they encompass a diversity of issues from metaphysics and epistemology. This article provides an introduction to the topic that illuminates how contemporary epistemological discussions took their shape historically and limns the contours of concrete cases of reduction in specific natural sciences. The unity of science and the impulse to accomplish compositional reduction in accord with a layer-cake vision of the sciences, the (...) seminal contributions of Ernest Nagel on theory reduction and how they strongly conditioned subsequent philosophical discussions, and the detailed issues pertaining to different accounts of reduction that arise in both physical and biological science (e.g., limit-case and part-whole reduction in physics, the difference-making principle in genetics, and mechanisms in molecular biology) are explored. The conclusion argues that the epistemological heterogeneity and patchwork organization of the natural sciences encourages a pluralist stance about reduction. (shrink)

This paper is an essay review of Steven French and Harmke Kamminga (eds.), Correspondence, Invariance and Heuristics. Essays in Honour of Heinz Post (Dordrecht: Kluwer, 1993). I distinguish a varity of correspondence relations between scientific theories (exemplified by cases from the book under review) and examine how one can make sense of the the prevailing continuity in scientific theorizing.