This paper is concerned with the description of the process of measurement within the context of a quantum theory of the physical world. It is noted that quantum mechanics permits a quasi-classical description of those macroscopic phenomena in terms of which the observer forms his perceptions. Thus, the process of measurement in quantum mechanics can be understood on the quasi-classical level by transcribing from the strictly classical observables of Newtonian physics to their quasi-classical counterparts the known rules for the measurement (...) of the former. The remaining physical problem is the delineation of the circumstances in which the correlation of a peculiarly quantum mechanical observable A with a classically measurable observable B can result in a significant measurement of A. This is undertaken within the context of quantum theory. The resulting clarification of the process of measurement has important implications relative to the philosophic interpretation of quantum mechanics. (shrink)

The purpose of this note is to examine a recent axiomatization of classical particle mechanics, and its relation to an alternative axiomatization I had earlier proposed. A comparison of the two proposals casts some interesting light on the problems of operationalism in classical celestial mechanics.1. Comparison of the Two Axiomatizations. The basic differences between the two proposals arise from the nature of the undefined terms. Both systems take the set of particles, time, and position as primitive notions. Both systems assume (...) that there exists a set of particles having continuous, twice-differentiable paths over some time interval. In addition, CPM takes mass and force as primitive notions, and assumes that with each particle there is associated a mass and a set of forces such that Newton's Second Law is satisfied. A system with these properties is called in CPM “a system of particle mechanics.” If, in addition, the set of forces in the system satisfies Newton's Third Law, the system is called in CPM “Newtonian.”. (shrink)

The overall purpose of this paper is to clarify the physical meaning and epistemological status of the term 'measurement' as used in quantum theory. After a review of the essential logical structure of quantum physics, Part I presents interpretive discussions contrasting the quantal concepts observable and ensemble with their classical ancestors along the lines of Margenau's latency theory. Against this background various popular ideas concerning the nature of quantum measurement are critically surveyed. The analysis reveals that, in addition to internal (...) mathematical difficulties, all the so-called quantum theories of measurement are grounded in unjustifiable, classical presuppositions. (shrink)

In this paper I expound an argument which seems to establish that probabilism and special relativity are incompatible. I examine the argument critically, and consider its implications for interpretative problems of quantum theory, and for theoretical physics as a whole.

This is the second, mathematically more detailed part of a paper consisting of two articles, the first having appeared in the immediately preceding issue of this Journal. It shows that a measurement converts a pure case into a mixture with reducible probabilities. The measurement as such permits no inference whatever as to the state of the physical system subjected to measurement after the measurement has been performed. But because the probabilities after the act are classical and therefore reducible, it is (...) often possible to adjust them so that Von Neumann's projection postulate is true. Among the more specific features dealt with in Part II is the occurrence of negative joint probabilities for the measurement of non-commuting operators in certain (not all!) quantum states. The general conclusions reached are stated at the end of the article. (shrink)

This essay contains a partial exploration of some key concepts associated with the epistemology of realist philosophies of science. It shows that neither reference nor approximate truth will do the explanatory jobs that realists expect of them. Equally, several widely-held realist theses about the nature of inter-theoretic relations and scientific progress are scrutinized and found wanting. Finally, it is argued that the history of science, far from confirming scientific realism, decisively confutes several extant versions of avowedly 'naturalistic' forms of scientific (...) realism. (shrink)

(1) The idea that diffraction of matter particles can only be understood in terms of a temporary wave transformation or 'double manifestation' is an uneconomical ad hoc hypothesis, shattered already in 1923 by the unitary quantum theory of diffraction of Duane which in 1926 became part of the quantum mechanics, with a statistical interpretation of wave-like appearances. (2) Bohr's re-interpretation of Heisenberg's uncertainty of prediction as an indeterminacy of existence rests on an illegitimate literal translation of a wave result into (...) particle language which is at variance with experience as well as with the statistical interpretation. (3) The fact that one can transform the simple and unitary particle mechanics into a complicated wavelike form is only a weak substitute for genuine dualism -- as if one would see dualism in the transformability from the geo- to the heliocentric reference system. (4) The strongest argument against a symmetry of the particle and the wave theory of matter is the explainability of the former in terms of simple postulates of invariance, leaving the wave formalism as a purely ad hoc construction. (shrink)

The present article is written by a theoretical physicist who, for some time, has endeavored to trace the origin of the concepts and principles of quantum theory to an empirical background broader than that afforded by delicate optical and mechanical experiments on a microphysical scale involving the microconstant h. In particular he tried to reduce the dominant role of probability in modern physics to irrefutable evidence of a quite general nature. As long as quantum probability is deduced from experience with (...) seemingly uncontrollable micro-mechanisms—think of radioactive disintegration as the most typical example—there will always be the objection that one day we still may find a hidden causality behind those small scale gambling devices called atoms, although one example of an exactly predictable atomic event would make present-day quantum theory untenable. In order to dislodge the remaining classicists from their fortress of doubt one may try to show that quantum probability is not an alibi for a temporary impotence of predicting microphysical events, but is a positive conclusion drawn from experience of a most general type, namely, from the principle of continuity, the basic tenet of the philosophy of Leibniz. (shrink)

The purpose of this paper is to solve a serious problem for the projection postulate involving the time-energy uncertainty relation. The problem was recently raised by Teller, who believes that the problem is insoluble and, consequently, that the projection postulate should no longer be regarded as a serious focus for interpretive investigation.

In this article I discuss the justification of scientific change and argue that it rests on different sorts of invariance. Against this background I consider notions of observation, meaning, and regulative standards. I sketch an account of the rationale of scientific change which preserves the merits and avoids the shortcomings of the approach of Feyerabend, Hanson, Kuhn, Toulmin, and others. Each of these writers would hold that transitions from one scientific tradition to another force radical changes in what is observed, (...) in the meanings of the terms employed, and in the metastandards involved. They would claim that "incommensurable" replacement is what does, and should, occur during scientific "revolutions." Such writers, however, have trouble in comparing different scientific theories. My account permits different theories to be compared in various ways. These comparisons, I argue, are possible through appeal to "first-level" and "second-level" invariance. In this connection I argue that observation, meaning, and regulative standards should be, and in fact usually are, nontrivially invariant with respect to scientific change. (shrink)

The distinction between discovery and justification is ambiguous. This obscures the debate over a logic of discovery. For the debate presupposes the distinction. Real discoveries are well established. What is well established is justified. The proper distinctions are three: initial thinking, plausibility, and acceptability. Logic is not essential to initial thinking. We do not need good supporting reasons to initially think of an hypothesis. Initial thoughts need be neither plausible nor acceptable. Logic is essential, as Hanson noted, to both plausibility (...) and acceptability. An hypothesis needs good supporting reasons to be either plausible or acceptable. Such reasons need not be relative to the particular scientific theory undergoing test at the time. There is no fundamental difference between reasons relevant to plausibility and acceptability. The difference is one of degree. Acceptability requires more than plausibility. (shrink)

This paper defends a realist interpretation of theories and a modest realism concerning the existence of quantities as providing the best account both of the logic of quantity concepts and of scientific measurement practices. Various operationist analyses of measurement are shown to be inadequate accounts of measurement practices used by scientists. We argue, furthermore, that appeals to implicit definitions to provide meaning for theoretical terms over and above operational definitions fail because implicit definitions cannot generate the requisite descriptive content. The (...) special case of establishing a temperature scale is examined to show that nonrealist accounts fail to provide insight into the theoretical connections that scientific laws postulate to hold among quantities. (shrink)

This paper considers the problem of causal explanation in classical and statistical thermodynamics. It is argued that the irreversibility of macroscopic processes is explained in both formulations of thermodynamics in a teleological way that appeals to entropic or probabilistic consequences rather than to efficient-causal, antecedental conditions. This explanatory structure of thermodynamics is not taken to imply a teleological orientation to macroscopic processes themselves, but to reflect simply the epistemological limitations of this science, wherein consequences of heat-work asymmetries are either macroscopically (...) measurable (entropy) or calculable (probabilities), while efficient-causal relationships are obscure or indeterminable. (shrink)

In the course of his researches in electromagnetism and the kinetic theory of gases, James Clerk Maxwell gave some thought to the nature of science itself. His observations in this field are of interest today not only because they are his, but because they are still instructive. Maxwell's views are to be found in the many asides with which he enlivened his scientific papers and treatises and in the various articles and reviews which he prepared for more popular consumption. The (...) topics discussed bear on his own contributions to physics; they include the logic of dynamical explanation, the method of physical analogy, and the perennial question of action at a distance versus contiguity. In the present essay, I wish to discuss Maxwell's views on dynamical explanation. (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)

Some features of physical science relevant for a discussion of physical explanation are mentioned. The D-N account of physical explanation is discussed, and it is seen to restrict the scope of explanation in physical science because it imposes the requirement that the explanandum must be deducible from the explanans. Analysis shows that an alternative view of scientific explanation, called the instance view, allows a wider range of physical explanations. The view is seen to be free from a certain class of (...) counter examples to the D-N theory. (shrink)

Heisenberg's principle of indeterminacy or uncertainty has led most theoretical physicists and philosophers to two important steps: 1) the denunciation of the law of physical causality; 2) the decision of biological and psychological problems in favor of indeterminism.

In his recently published book, The Nature of Physical Reality, Professor Margenau develops a conception of physical reality, which, on the one hand, is a repudiation of radical empiricism and which, on the other hand, is a denial of realism. Margenau believes that he has accomplished his task by means of “constructs” which, in “a large area of discourse,” are “wholly synonymous” with concepts and which, nevertheless, when verified, are “the external objects”.

Achinstein, Putnam, and others have urged the rejection of the received view on theories (which construes theories as axiomatic calculi where theoretical terms are given partial observational interpretations by correspondence rules) because (i) the notion of partial interpretation cannot be given precise formulation, and (ii) the observational-theoretical distinction cannot be drawn satisfactorily. I try to show that these are the wrong reasons for rejecting the received view since (i) is false and it is virtually impossible to demonstrate the truth of (...) (ii). Nonetheless, the received view should be rejected because it obscures a number of epistemologically important features of scientific theorizing. I show this by sketching an alternative analysis which reveals some of these features and gives a more faithful picture of scientific theorizing. (shrink)

Biological foundations of the psychoneural identity hypothesis are explicated and their implications discussed. "Consciousness per se" and phenomenal contents of consciousness per se are seen to be identical with events in the (unobserved) brain in accordance with Leibniz's Law, but only informationally equivalent to neural events as observed. Phenomenal content potentially is recoverable by empirical means from observed neural events, but the converse is not possible. Consciousness per se is identical with events which do not represent anything distal to sensory (...) receptor-transducer systems. Thus, on the psychoneural identity hypothesis, consciousness per se comprises directly physical events-in-themselves rather than being a Euclidean representation of physical events as is the case for phenomenal content. After comparing consciousness per se to "onta," a paradox is suggested: rather than being irreducible to physical reality, consciousness per se is the only experience congruent with the ultimate nature of physical reality as conceived by contemporary physics. (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)

In considering the possibility that the fundamental particles of matter might violate Leibniz's Principle, one is confronted with logical proofs that the Principle is a Theorem of Logic. This paper shows that the proof of that theorem is not universal enough to encompass entities that might not be unique, and also strongly suggests that photons, for example, do violate Leibniz's Principle. It also shows that the existence of non-individuals would imply the breakdown of Quine's criterion of ontological commitment.

It has been tacitly assumed that certain fundamental “laws” of science have the same meaning and significance in the different scientific disciplines. Outside of quantum physics the law of causality was regarded as such a concept which was most generally applicable in the description of the systems of nature. However, the role of causality in recent research in biology seems not quite clear. There an explanation of the specific properties of biological systems does not assume the form of a simple (...) law such as a mathematical expression relating different states of one and the same system. Rather it is attempted to show how the properties of the system as a whole are established by the specific interaction of the parts of the system. (shrink)

The problem of the critical assessment of theories across paradigms raised by Kuhn is not resolved, it is argued, either by Scheffler's appeal to initial credibility or by Lakatos' conception of a research program. It is argued further that, in these contexts, the notion of reasonable choice by individuals makes no sense. The conclusion supports Feyerabend's position of "epistemological anarchism.".

The science of the 19th and early 20th century permitted the view that all human experience is subject to the deterministic laws of physics. Reality was conformable with these laws, and the laws could be used to designate what is real.

“What did the President know and when did he know it?”Senator Howard Baker, Watergate hearings, 1973Why do scientists accept or reject theories? More specifically: why do they change from one theory to another? What is the role of empirical tests in the evaluation of theories?This paper focuses on a narrowly-defined question: in judging theories, do scientists give greater weight (other things being equal) to successfulnovel predictionsthan to successful deductions of previously-known facts? The affirmative answer is called the “predictivist thesis” (Maher (...) 1988).It is primarily philosophers who are interested in this question, and they have treated it mostly as a normative or logical problem. Can the writings of historians of science tell us how scientists have treated novel predictions in the past? Until recently historians have rarely addressed this point. (shrink)

This portion of the essay concludes a two-part paper, Part I of which appeared in an earlier issue of this Journal. Part II begins with a careful study of the quantum description of real experiments in order to motivate a proposal that two distinct quantum theoretical measurement constructs should be recognized, both of which must be distinguished from the concept of preparation. The different epistemological roles of these concepts are compared and explained. It is then concluded that the only possible (...) type of "quantum measurement theory" is one of little metaphysical interest and that quantum measurement seems problematical only when viewed from an overly narrow classical perspective. (shrink)

the author has outlined several of the more important interpretations of measurement in quantum mechanics and discussed the problems arising from them. Particular attention was paid to the work of Bohr, Heisenberg and von Neumann and a tentative proposal was made for a possible interpretation which would mitigate some of the problems and dilemmas. This interpretation was essentially that proposed by Margenau in terms of latent variables. He defines measurement to be any operation with physical apparatus which results in a (...) number, including in this, of course, yes and no answers as well as conventional numerical answers. Further he makes the distinction between the preparation of a state and the measurement of the state. A preparation puts the quantum system into a particular state whereas the measurement frequently destroys the state in question. This paper presents several criteria to help in the evaluation of the alternatives presented in the first paper and carries further the suggested interpretation mentioned at the end of that paper. (shrink)

I characterize a notion of causal agency that is the causitive component of many transitive verbs. The agency of what I call substantial causes relates objects physically to systems with which they interact. Such agent causation does not reduce to conditionship relations, nor does it cease to play a role in scientific discourse. I argue, contrary to regularity theories, that causal claims do not in general depend for their sense on generalities nor do they entail the existence of laws. Clarification (...) of the relationships among substantial causes, causal processes, and explanatory conditions separates the analysis of causal connection from that of nomological connection. This clarification is then applied to a variety of issues in the analysis of causality. (shrink)

The methodology of the empirical sciences is treated from a set-theoretical point of view. Starting from Tarski's formulation of the methodology of the deductive sciences, a relation between terms, called degree of centrality, is introduced. Epistemic correlation, and therefore the notion of interpretative system, is defined using this relation.

How are causes and laws related? Some attempt to analyze causal relations in terms of laws, others view causal explanation as quite distinct from explanation using laws. My analysis of the relations between causes and laws focuses on cases such as the simple pendulum law where asymmetries in causal relations between quantities are not reflected in the functional dependencies in the law equations. The asymmetry puzzle has elicited a variety of accounts which reflect quite different views on the relation between (...) causes and laws and their roles in scientific explanation. Finding none of the usual accounts satisfying, I offer an explication based on some distinctions in the analysis of the relevant causes that are not commonly heeded. I criticize the very notion of causal law and examine some implications of my account forceteris paribusproblems which arise in attempts to give realist interpretations of scientific theories. (shrink)

The developments in 20th century physics which have brought into question the status of causality in subatomic phenomena are common knowledge today in the philosophical world. For the purposes of our discussion attention focusses on the quantum-mechanical solutions which describe atomic states by probability distributions instead of by exact values of observable variables.

In the interesting discussion between Margenau and Werkmeister a baffling dilemma arises:If verification of constructs makes up reality, and if verifications work retroactively, several different realities may exist at the same time.The writer, who—as a positivist—cannot accept a transcendental reality, as Werkmeister seemingly does, is not disturbed by a multitude of realities. He identifies reality with the most familiar and most generalized cognition. As such it varies with the mechanism of cognition and with the type and degree of integration.