Mr. Sharp's resolution of the Einstein-Podolsky-Rosen paradox is, in my opinion, the right one. However, the resolution does not in my opinion show that “God's in his heaven; all's right with the world.” This is in no way a criticism of Sharp; rather, it is inevitable that any resolution of this paradox, dealing as it does with the quantum mechanical concept of “measurement”, must tangle with some of the real difficulties which are lurking in the notion. The purpose of these (...) comments is to use Mr. Sharp's remarks as a basis for bringing out one of the serious conceptual difficulties connected with measurement. (shrink)

Es werden die Veränderungen der Wissenschaftssprache der Physik untersucht, die durch den Übergang von der klassich-relativistichen Physik zur Quantenphysik erfolgt sind. Die neuen und prinzipiellen Beschränkungen der Möglichkeiten der Überprüfung wissenschaftlicher Aussagen führen zu Reduktionen der hypothetischen Annahmen, die der Sprache der klassischen Physik zu Grunde liegen. Diese Reduktionen haben ihrerseits Abschwächungen der syntaktischen Strukturen zur Folge, die besonders in der formalen Logik und der Modallogik deutlich werden. Diese auf schwächeren Prämissen basierenden Strukturen sind die Quanten-Logik und die Quanten-Modallogik, die (...) damit auch einen weiteren Geltungsbereich besitzen als die entsprechenden klassischen formalen Systeme. (shrink)

We list, with discussions, various principles of scientific realism, in order to exhibit their diversity and to emphasize certain serious problems of formulation. Ontological and epistemological principles are distinguished. Within the former category, some framed in semantic terms (truth, reference) serve their purpose vis-a-vis instrumentalism (Part 1). They fail, however, to distinguish the realist from a wide variety of (constructional) empiricists. Part 2 seeks purely ontological formulations, so devised that the empiricist cannot reconstruct them from within. The main task here (...) is to characterize "independence of mind". A pair of notions, "physical invariance" and "anti-determination", seem to work. They enable us to assess anew "the problem of constructing the physical out of the phenomenal" (yielding certain clarifications demanded by Goodman). Modern cosmology, especially, is seen to present insuperable obstacles to such empiricist approaches to science. The final section on epistemological principles reveals a morass better avoided in favor of an elementary claim about perception, together with a rejection of any absolute observation/theory dichotomy. Finally, a positive, realist notion of "observable-in-principle" is sketched, and it is suggested that, from the perspective of relativistic cosmology, even this defines no boundary to potential knowledge. (shrink)

The work of Gleason and of Kochen and Specker has been thought to refute a naïve realist approach to quantum mechanics. The argument of this paper substantially bears out this conclusion. The assumptions required by their work are not arbitrary, but have sound theoretical justification. Moreover, if they are false, there seems no reason why their falsity should not be demonstrable in some sufficiently ingenious experiment. Suitably interpreted, the work of Bell and Wigner may be seen to yield independent arguments (...) for the falsity of naïve realistic approach to quantum mechanics. Quantum mechanics is no more like classical statistical mechanics than its creators thought it was. (shrink)

Sometimes a theory is interpreted realistically--i.e., as literally true--whereas sometimes a theory is interpreted instrumentalistically--i.e., as merely a convenient device for summarizing, systematizing, deducing, etc., a given body of observable facts. This paper is part of a program aimed at determining the basis on which scientists decide on which of these interpretations to accept a theory. I proceed by examining one case: the nineteenth-century debates about the existence of atoms. I argue that there was a gradual transition from an instrumentalist (...) to a realistic acceptance of the atomic theory, because of gradual increases in its predictive power, the "testedness" of its hypotheses, the "determinateness" of its quantities, and because of resolutions of doubts about the acceptability of its basic explanatory concepts. (shrink)

Heisenberg'sgendanken experiments in quantum mechanics have given rise to a widespread belief that the indeterminacy relations holding for the variables of a quantal system can be explained quasiclassically in terms of a disturbance suffered by the system in interaction with a quantal measurement, or state preparation, agent. There are a number of criticisms of this doctrine in the literature, which are critically examined in this article and found to be ininconclusive, the chief error being the conflation of this disturbance with (...) the projection postulate. We present a critique of the disturbance theory based on the fact that the required disturbance will in general depend on the interaction time of the system and state-preparer. This point is exploited in the construction of a spin-interaction model which acts as a counterexample to the disturbance doctrine, while remaining faithful to the spirit of Heisenberg'sgedanken experiments. Several consequences of this result are discussed. (shrink)