Semiconduction theory

Conclusions The semiconducting properties of biomacromolecules are a certainty which cannot be neglected when models are proposed for explaining some biological function such as, enzymatic activity of cytochrome oxidase, olfactory transduction, visual reception, properties of the cellular membranes, etc.^6,7,9. Although a perfect correlation does not yet exist between the results of molecular orbital calculations and experimental data regarding the electrical conduction in proteins and nucleic acids⁹, a profound study on the aspects connected with intrinsic mechanisms of conduction in biomacromolecules, as well as on dependence of electrical properties on the impurities acting in vivo, should increase our understanding of biophysical phenomena.     

New tools for theory choice and theory diagnosis

Theory choice can be approached in at least four ways. One of these calls for the application of decision theory, and this article endorses this approach. But applying standard forms of decision theory imposes an overly demanding standard of numeric information, supposedly satisfied by point-valued utility and probability functions. To ameliorate this difficulty, a version of decision theory that requires merely comparative utilities and plausibilities is proposed. After a brief summary of this alternative, the article illustrates how comparative decision theory affords a rational reconstruction of decisions made by exemplary scientists in two cases of theory choice: Buffon’s law and the luminiferous ether. It also offers a rational reconstruction of two cases of theory diagnosis: Mendeleev’s anomalies and the Pioneer anomaly.     

Kirchhoff's theory of rods

Communicated by C. Truesdell     

Probability in GRW theory

GRW theory postulates a stochastic mechanism assuring that every so often the wave function of a quantum system is ‘hit’, which leaves it in a localised state. How are we to interpret the probabilities built into this mechanism? GRW theory is a firmly realist proposal and it is therefore clear that these probabilities are objective probabilities (i.e. chances). A discussion of the major theories of chance leads us to the conclusion that GRW probabilities can be understood only as either single case propensities or Humean objective chances. Although single case propensities have some intuitive appeal in the context of GRW theory, on balance it seems that Humean objective chances are preferable on conceptual grounds.     

Ehrenfest’s adiabatic theory and the old quantum theory, 1916–1918

I discuss in detail the contents of the adiabatic hypothesis, formulated by Ehrenfest in 1916. I focus especially on the paper he published in 1916 and 1917 in three different journals. I briefly review its precedents and thoroughly analyze its reception until 1918, including Burgers’s developments and Bohr’s assimilation of them into his own theory. I show that until 1918 the adiabatic hypothesis did not play an important role in the development of quantum theory. An erratum to this article can be found at     

A pre-euclidean theory of proportions

Communicated by B. L. van der Waerden     

Norton's material theory of analogy

In his book, The Material Theory of Induction, Norton argues that the quest for a universal formal theory or ‘schema’ for analogical inference should be abandoned. In its place, he offers the “material theory of analogy”: each analogical inference is “powered” by a local fact of analogy rather than by any formal schema. His minimalist model promises a straightforward, fact-based approach to the evaluation and justification of analogical inferences. This paper argues that although the rejection of universal schemas is justified, Norton's positive theory is limited in scope: it works well only for a restricted class of analogical inferences. Both facts and quasi-formal criteria have roles to play in a theory of analogical reasoning.     

Francis Hauksbee's theory of electricity

Conclusion Historians of science have usually assumed that the science of electricity developed in the period prior to Franklin, or at least prior to Nollet, in what amounted to a theoretical vacuum. It has been my aim in this paper to demonstrate the falsity of that assumption. I have shown, I hope, that Hauksbee's important researches were guided throughout by strong theoretical considerations, and I have indicated that Dufay's even more important studies were guided by exactly the same considerations. Nor was their theory in any sense a stagnant one. As it was developed by Hauksbee, it could give a fairly adequate explanation of almost all the known electrical phenomena; it even enabled him to predict the outcome of experiments such as the one involving the rubbing of a globe while it was positioned near a second, exhausted, globe. With the discovery of so many new phenomena in the 1730's, the theory turned out to be no longer adequate, but it is not at all surprising that it was a few years before the full extent of its inadequacies was appreciated, nor is it surprising that a strong continuity is evident between it and the theory which eventually replaced it. In the meantime, the theory continued to serve a useful function by suggesting new lines of research to its adherents. The theory functioned, then, in the same way as any other scientific theory, and it deserves a more serious treatment than it has usually received. This paper, I hope, can serve as a beginning.