Edward MacKinnon

Aristotele. Science as a systematic explanation through causes.--Newton, I. Rules and reflections on scientific reasoning.--Carnap, R. Empiricism, semantics, and ontology.--Hempel, C. On the logic of explanation.--Nagel, E. The realist view of theories.--Quine, W. V. On the role of logic in explanation.--Harris, E. E. Method and explanation in metaphysics.--Einstein, A. Remarks on Bertrand Russell's theory of knowledge.--Sellars, W. The language of theories.--MacKinnon, E. Atomic physics and reality.--Bunge, M. Physics and reality.--Heelan, P. A. Quantum mechanics and objectivity.--Bibliographical essay (p. 285-301).

This article probes the question of what interpretations of quantum mechanics actually accomplish. In other domains, which are briefly considered, interpretations serve to make alien systematizations intelligible to us. This often involves clarifying the status of their implicit ontology. A survey of interpretations of non-relativistic quantum mechanics supports the evaluation that these interpretations make a contribution to philosophy, but not to physics. Interpretations of quantum field theory are polarized by the divergence between the Lagrangian field theory that led to the Standard Model of Particle physics and the Algebraic quantum field theory, that discounts an ontology of particles. Ruetsche's interpretation, it is argued, offers a potential for loosening the sharp polarization that presently obtains. A brief evaluation focuses on the functional ontology of quantum field theory considered as an effective theory.

An epistemological interpretation of quantum mechanics hinges on the claim that the distinctive features of quantum mechanics can be derived from some distinctive features of an observational basis. Old and new variations of this theme are listed. The program has a limited success in non-relativistic quantum mechanics. The crucial issue is how far it can be extended to quantum field theory without introducing significant ontological postulates. A C*-formulation covers algebraic quantum field theory, but not the standard model. Julian Schwinger’s anabatic methodology extended a strict measurement-based formulation of quantum mechanics through field theory. His extension also excluded the quark hypothesis and the standard model. Quarks and local gauge invariance are postulates that go beyond the limits of an epistemological interpretation of quantum mechanics. The ontological significance ascribed to these advances depends on the role accorded ontology.

Philosophical interpretations of theories generally presuppose that a theory can be presented as a consistent mathematical formulation that is interpreted through models. Algebraic quantum field theory (AQFT) can fit this interpretative model. However, standard Lagrangian quantum field theory (LQFT), as well as quantum electrodynamics and nuclear physics, resists recasting along such formal lines. The difference has a distinct bearing on ontological issues. AQFT does not treat particle interactions or the standard model. This paper develops a framework and methodology for interpreting such informal theories as LQFT and the standard model. We begin by summarizing two minimal epistemological interpretation of non-relativistic quantum mechanics (NRQM): Bohrian semantics, which focuses on communicables; and quantum information theory, which focuses on the algebra of local observables. Schwinger's development of quantum field theory supplies a unique path from NRQM to QFT, where each step is conceptually anchored in local measurements. LQFT and the standard model rely on postulates that go beyond the limits set by AQFT and Schwinger's anabatic methodology. The particle ontology of the standard model is clarified by regarding the standard model as an informal modular theory with a limited range of validity.

In the course of his long development, Kant's concept of matter changed somewhat, while his concept of scientific explanation changed considerably. Both developments achieved a coherent integration in Kant's Metaphysical Foundations of Natural Science. Using this developmental background, the present paper argues that the Foundations should be interpreted as an attempted rational reconstruction of the mechanics of Newton and Euler. Kant attempted to do this by constructing a concept of matter that would confer a Leibnizian intelligibility on Newtonian mechanics, and also accord with Kant's theories on the nature of concepts and their role in scientific explanation.

One of the key interpretative problems generated by the development of quantum theory was the conceptual consistency underlying scientific change, a problem not adequately treated by any of the leading theories of scientific development. In different but related ways Quine, Sellars, and Davidson have treated the problem of conceptual consistency by showing how one can begin with ordinary language and proceed to specialized extensions. Their techniques have not been applied to modern physics. However, one basis for applying them arises from the deep similarities between some of the work of these analysts and the Copenhagen interpretation rightly interpreted. To make this more concrete three concepts whose meanings have changed as a result of scientific progress are considered: 'atom', 'state of a system', and 'particle'. Each functions in a different way and requires a different type of analysis.

ABSTRACT. The objectivity of physics has been called into question by social theorists, Kuhnian relativists, and by anomalous aspects of quantum mechanics. Here we focus on one neglected background issue, the categorical structure of the language of classical physics. The first half is an historical overview of the formation of the language of classical physics, beginning with Aristotle's Categories and the novel idea of the quantity of a quality introduced by medieval Aristotelians. Descartes and Newton at-tempted to put the new mechanics on an ontological foundation of atomism. Euler was the pivotal figure in basing mechanics on a macroscopic concept of matter. The second scientific revolution, led by Laplace, took mechanics as foundational and attempted to fit the Baconian sciences into a framework of atomistic mechanism. This protracted effort had the unintended effect of supplying an informal unification of physics in a mixture of ordinary language and mechanistic terms. The second half treats LCP as a linguistic para-site that can attach itself to any language and effect mutations in the host without chang-ing its essential form. This puts LCP in the context of a language of discourse and sug-gests that philosophers should concentrate more on the dialog between experimenters and theoreticians and less on analyses of theories. This orientation supplies a basis for treating objectivity

This article completes the study begun in I by a detailed consideration of errol harris's, "the foundations of metaphysics in science" and by an independent interpretation of the epistemological foundations of scientific theories. This is done in terms of two components labelled 'a physical language' and 'a mathematical language'. A physical language is conceived as a transformed extension of ordinary language which preserves its basic structural principles while modifying its descriptive metaphysics. The relation between such a physical language and a mathematical system is explained by a correspondence between second order physical predicates and first order mathematical predicates

There are two opposing traditions in contemporary quantum field theory (QFT). Mainstream Lagrangian QFT led to and supports the standard model of particle interactions. Algebraic QFT seeks to provide a rigorous consistent mathematical foundation for field theory, but cannot accommodate the local gauge interactions of the standard model. Interested philosophers face a choice. They can accept algebraic QFT on the grounds of mathematical consistency and general accord with the semantic conception of theory interpretation. This suggests a rejection of particle ontology. Or they can accept the standard model on the grounds of its established success. This alternative, which I defend, suggests revising philosophical accounts of scientific theory and finding some way of accommodating particles.

In place of earlier instrumentalist and phenomenalist interpretations of science both Quine and Sellars have developed highly influential realist positions centering around the doctrine that accepting a theory as explanatory and irreducible rationally entails accepting the entities posited by the theory. A growing reaction against this realism is partially based on perceived inadequacies in the doctrines of Quine and Sellars, but even more on reconstructions of scientific explanations which do not involve such ontic commitments. Three types of anti-realistic positions are considered and criticized. Hesse's neo-Duhemian position couples a statistical theory of inference to a downgrading of purely theoretical statements. Sneed uses the method of axiomatrization through set-theoretic predicates to supply a reconstruction of Kuhn's account of scientific development. Here Ramsey-reduction sentences serve to eliminate purely theoretical terms. The longest section deals with van Fraassen's semantic model based on a state-space representation of scientific theories and the use of this model in interpreting quantum mechanics. It is argued that the model is valuable, but that the anti-realist interpretation accorded it is not justified and entails serious inconsistencies