Hasok Chang

Preservative Realism and Its Discontents: Revisiting Caloric

A popular and plausible response against Laudans “pessimistic induction” has been what I call “preservative realism,” which argues that there have actually been enough elements of scientific knowledge preserved through major theory‐change processes, and that those elements can be accepted realistically. This paper argues against preservative realism, in particular through a critical review of Psilloss argument concerning the case of the caloric theory of heat. Contrary to his argument, the historical record of the caloric theory reveals that beliefs about the properties of material caloric, rejected by subsequent theories, were indeed central to the successes of the caloric theory. Therefore caloric remains a favorable case for Laudan. Further, I argue that even confirmed cases of preservation do not warrant an inference to truth.

Turning an undergraduate class into a professional research community

I describe here an ongoing pilot project aimed at a full integration of teaching and research at the undergraduate level. Our chief innovation is the mechanism of inheritance: each year students receive a body of work produced by the previous group of students and make improvements and additions to it; this process can be repeated until publishable materials are produced. This is part of a system of learning that enables students to function as a real and evolving community of researchers.

History and Philosophy of Science as a Continuation of Science by Other Means

History and philosophy of science can serve the function of investigating scientific questions that are excluded by science itself. Because many things need to be protected from questioning and criticism in specialist science, its demonstrated effectiveness is also unavoidably accompanied by a loss of knowledge and a degree of dogmatism. History and philosophy of science can ameliorate this situation by working as a shadow discipline complementing specialist science in the production of knowledge about nature. In this enterprise the connection between philosophy of science and history of science is essential, since the questions that get consigned to the realm of philosophy are often, and not accidentally, the same ones buried in the historical record of past science. Some examples are given illustrating the complementary mode of history and philosophy of science, and its relations to other modes of study in history of science and philosophy of science are also examined.

How to Take Realism Beyond Foot-Stamping

Au-dela du debat sur la credibilite des resultats scientifiques et sur le realisme empirique, lA. presente une autre version du realisme qui sappuie sur le critere de la plausibilite ontologique, et qui permet a la science de remplir sa fonction mythologique.

Acidity: The Persistence of the Everyday in the Scientific

Acidity provides an interesting example of an everyday concept that developed fully into a scientific one; it is one of the oldest concepts in chemistry and remains an important one. However, up to now there has been no unity to it. Currently two standard theoretical definitions coexist (Brønsted and Lowry’s and Lewis’s); the standard laboratory measure of acidity, namely the pH, only corresponds directly to the Brønsted-Lowry concept. The lasting identity of the acidity concept in modern chemistry is based on the persistence of the quotidian concept. This is suggestive for considerations of other scientific concepts.

A Case for Old-Fashioned Observability, and a Reconstructed Constructive Empiricism

I develop a concept of observability that pertains to qualities rather than objects: A quality is observable if it can be registered by human sensation (possibly with the aid of instruments) without involving optional interpretations. This concept supports a better description of observations in science and everyday life than the object‐based observability concepts presupposing causal information‐transfer from the object to the observer. It also allows a rehabilitation of the traditional empiricist distinction between observations and their interpretations, but without a presumption that observations are infallible. Using this concept of observability, I also propose a re‐formulation of constructive empiricism that is easier to defend against realist attacks, while open to reasonable realist intuitions.

The quantum counter-revolution: Internal conflicts in scientific change

Abstract Many of the experiments that produced the empirical basis of quantum mechanics relied on classical assumptions that contradicted quantum mechanics. Historically this did not cause practical problems, as classical mechanics was used mostly when it did not happen to diverge too much from quantum mechanics in the quantitative sense. That fortunate circumstance, however, did not alleviate the conceptual problems involved in understanding the classical experimental reasoning in quantum-mechanical terms. In general, this type of difficulty can be expected when a coherent scientific tradition undergoes a theoretical upheaval. The problem may be circumvented through the use of phenomenological theory in experimentation during the period of theoretical instability.

ON THE APPLICABILITY OF THE QUANTUM MEASUREMENT FORMALISM

Customary discussions of quantum measurements are unrealistic, in the sense that they do not reflect what happens in most actual measurements even under ideal circumstances. Even theories of measurement which discard the projection postulate tend to retain two unrealistic assumptions of the von Neumann theory: that a measurement consists of a single physical interaction, and that the topic of every measurement is information wholly contained in the quantum state of the object of measurement. I suggest that these unrealistic assumptions originate from an overly literal interpretation of the operator formalism of quantum mechanics. I also suggest, following Park, that some issues can be clarified by distinguishing the sense of the term measurement occurring in the quantum-mechanical operator formalism, and the sense of measurement that refers to actual processes of gaining information about the physical world.

The absolute and its measurement : William Thomson on temperature

In this paper we give a full account of the work of William Thomson (Lord Kelvin) on absolute temperature, which to this day provides the theoretical underpinnings for the most rigorous measurements of temperature. When Thomson fashioned his concepts of ‘absolute’ temperature, his main concern was to make the definition of temperature independent of the properties of particular thermometric substances (rather than to count temperature from an absolute zero). He tried out a succession of definitions based on the thermodynamics of ideal heat engines; most notably, in 1854 he gave the ratio of two temperatures as the ratio of quantities of heat taken in and given out at those temperatures in a Carnot cycle. But there were difficulties with using such definitions for experimental work, since it was not possible even to approximate an ideal Carnot engine in reality. More generally, it is not trivial to connect an abstract concept with concrete operations in order to make physical measurements possible. In the end, Thomson argued that an ideal gas thermometer would indicate his absolute temperature, and that the deviation of actual gas thermometers from the ideal could be estimated by means of the Joule‐Thomson effect. However, the measurement of the Joule‐Thomson effect itself required measurements of temperature, so there was a problem of circularity.