In defending NOA against some contemporary antirealisms I distinguish two antirealist camps: the epistemology inflaters, who come to their antirealism by filling up inquiry and belief formation with various warrants and principles of justification, and the semantic inflaters, or truthmongers, who come to their antirealism by exchanging truth for some epistemic notion, like ideal rational acceptablility. In parity with arguments against the correspondence theory of truth, which I see at the heart of various realisms, I argue against antirealist truthmongering in two ways. One is inductive and hortative. I point to the history of failures of all past attempts at theories of truth, and try to suggest better things for philosophy to do instead. The other way is deconstructive. I examine the attempted explications of truth in the terms set by their own discourses, and try to show that they cannot actually stand on their own there. Lily Knezevich looks at this deconstructive work in her ‘Truthmongering‘ and finds it flawed by what I will call ‘Knezevich’s fallacy.’ (Generously, she refers to it as my fallacy. But surely the rule in these things is to let the name, and therefore the honor, attach to the discoverer, not the alleged perpetrator.)

Niedenthal et al. recognize that cultural differences are important when interpreting facial expressions. Nonetheless, many of their core observations derive more from individualistic cultures than from collectivist cultures. We discuss two examples from the latter: (1) lower rates of mutual eye contact, and (2) the ubiquity of specific “functional smiles.” These examples suggest constraints on the assumptions and applicability of the SIMS model.

Child's play? Certainly Alison Gopnik is in good company in pointing to connections between science and child development. To mention just a few luminaries: in psychology, Freud (followed by Erikson and Piaget) looked at the developmental connection between children's play and adult work; in philosophy, Thomas Reid may have been the first to ground the faculty of reasoning in developmental stages that “unfold themselves by degrees; so that it [the child] is inspired with the various principles of common sense” (1764, V, 7). As for connecting commonsense reasoning and science, according to Einstein, “The whole of science is nothing more than a refinement of everyday thinking” (1954, 290). Quod erat demonstrandum.

This paper argues that Einstein subscribed to three distinct kinds of interpretations of the quantum theory: subjective, instrumental, and hidden variables interpretations. We explore the context and ihe content of Einstein's thinking over these interpretations, emphasizing Einstein's conception of his role not only as a critic of the new quantum theory but also as a guide pointing the way to better physics.

In the quantum theory the state of an evolving system is represented by a function that depends on time and perhaps on some other parameters. It is generally called the “psi-function”, and it evolves according to an equation called the Schrödinger equation. Indeed Schrödinger introduced the psi-function into physics. In the beginning (i.e., in 1926) Schrödinger thought that the psi-function referred to a fuzzy bit of reality. That is, he pictured an electron, whose state was given by a certain psi-function, as a pulsating bit of electricity, something like an electrical cloud or a patch of electrical fog. In short order, however, Schrödinger saw difficulties with this interpretation, and after trying out more sophisticated refinements he abandoned the whole project. What he abandoned was the program of trying to interpret the psi-function as directly representing some spatiotemporal features of the object whose state it characterized.

Correlations between the behavior of pairs of particles are generated in the following experimental situation. An on-line source emits a stream of two-particle systems, where each system is in one and the same quantum state. After emission, the particles – call then (I) and (II) – move off in opposite directions. Each particle then encounters one of several possible barriers that either it passes or doesn't. A short distance behind each barrier is a detector set to register the presence of the particle, should it get that far. Finally, the detectors are connected by a timed relay and counter that registers a “coincidence count” should the two detectors fire within a set, brief time interval. When the experiment is run with various different barriers, detection rates accumulate for each barrier singly, and coincidence rates (the correlations) for the various pairs of barriers.

I once wrote to Imré Lakatos that if he had not already established himself as an accomplished philosopher and provocateur, he could have made a successful career as a Hollywood script writer. I had in mind, at that time, a beautifully written paper he had constructed by pasting together the cuttings from other papers. I had forgotten that his reputation as a dramatist was already established, with the production of his Proofs and Refutations [9]. For that work, it seems to me, is simply a play within a play. The main character, whose part is written in the footnotes, delivers a monologue which is a commentary on the drama, between teacher and students, that occupies center stage. This main character is not named in the play, so for ease of reference I shall call him “Imré”. What Imré points out is that the drama on center stage imitates life, in showing us the essential features of the methodology by virtue of which mathematical science grows.

In 1924, Bohr, Kramers and Slater tried to introduce into microphysics conservation principles that hold only on the average. This attempt was abandoned in the light of the Compton-Simon experiment (and its later refinements). Since that time, except for a moment of doubt in 1936, it has been thought that the classical conservation laws (for energy and momentum) hold in quantum theory for each individual interaction, in a way that yields the classical exchange-and-balance of momentum (or energy) familiar from the laws of elastic collisions. It has been thought, that is, that in each individual “collision” what one part of the total system loses in linear momentum (say) another part gains, so as to maintain the same total amount afterwards as before. To those familiar with discussions of the interpretation of quantum theory, however, it will be apparent that the very concepts needed to express this idea of an elastic collision are generally not admitted in the theory. For one needs the idea that both before and after collision the total system has a well-defined value for the conserved quantity and, moreover, that the various component parts of the system have well-defined values for those quantities out of which the conserved one is composed. But in the case of spin, for example, it is customary to say that although total spin may be conserved in certain interactions one cannot attribute values to the separate components of spin (in various directions) because the associated operators do not commute. (Thus the whole sum is not even the sum of its parts.) Moreover, one does not generally refer to the values of quantities except in eigenstates. Hence, in general, one would not refer to the value of the conserved quantity before and after interaction, except for interactions initiated in eigenstates.

We use the term ‘measurement’ to refer to the interaction between an object and an apparatus on the basis of which information concerning the initial state of the object may be obtained from information on the resulting state of the apparatus. The quantum theory of measurement is a quantum theoretic investigation of such interactions in order to analyse the correlations between object and apparatus that measurement must establish. Although there is a sizeable literature on quantum measurements there appear to be just two sorts of interactions that have been employed. There are the ‘disturbing’ interactions consistent with the analysis of Landau and Peierls (8) as developed by Pauli (11) and by Landau and Lifshitz (7), and there are the ‘non-disturbing’ interactions explicitly set out by von Neumann ((10), chs. 5, 6), and that dominate the literature. In this paper we shall investigate the most general types of interactions that could possibly constitute measurements and provide a precise mathematical characterization (section 2). We shall then examine an interesting subclass, corresponding to Landau's ideas, that contains both of the above sorts of measurements (section 3). Finally, we shall discuss von Neumann measurements explicitly and explore the purported limitations suggested by Wigner(12) and Araki and Yanase (2). We hope, in this way, to provide a comprehensive basis for discussions of quantum measurements.

The aim of this paper is to present and discuss a probabilistic framework that is adequate for the formulation of quantum theory and faithful to its applications. Contrary to claims, which are examined and rebutted, that quantum theory employs a nonclassical probability theory based on a nonclassical “logic,” the probabilistic framework set out here is entirely classical and the “logic” used is Boolean. The framework consists of a set of states and a set of quantities that are interrelated in a specified manner. Each state induces a classical probability space on the values of each quantity. The quantities, so considered, become statistical variables (not random variables). Such variables need not have a “joint distribution.” For the quantum theoretic application, there is a uniform procedure that defines and determines the existence of such “joint distributions” for statistical variables. A general rule is provided and it is shown to lead to the usual compatibility-commutivity requirements of quantum theory. The paper concludes with a brief discussion of interference and the misunderstandings that are involved in the false move from interference to nonclassical probability.