The thesis of the empirical underdetermination of theories (U-thesis) maintains that there are incompatible theories which are empirically equivalent. Whether this is an interesting thesis depends on how the term incompatible is understood. In this paper a structural explication is proposed. More precisely, the U-thesis is studied in the framework of the model theoretic or emantic approach according to which theories are not to be taken as linguistic entities, but rather as families of mathematical structures. Theories of similarity structures are (...) studied as a paradigmatic case. The structural approach further reveals that the U-thesis is related to problems of uniqueness in the representational theory of measurement, questions of geometric conventionalism, and problems of structural underdetermination in mathematics. (shrink)

The following investigation illustrates, by concrete historical examples, some of the basic results, outlined in earlier papers on theory evolution and reference dynamics in science (cf. Balzer, W. et al.: 1989, 'A Static Theory of Reference in Science', Synthese 79, 319-360; Lauth, B.: 1989, 'Reference Problems in Stoichiometry', Erkenntnis 30, 339-362; Lauth, B.: 1990, 'Theory Evolution and Reference Kinematics', Synthese 88, 279-307). All theories considered in this paper are represented within a metatheoretical frame that has become known as the structuralist (...) view in the philosophy of science. The paper focusses on some physical constants, namely the mass and charge of electrons, henceforth denoted by m₀ and e₀, of Boltzmann's constant k, Faraday's constant F and Avogadro's Number ${\rm N}_{{\rm A}}$ , and the evolution of their 'reference spectra' from the beginning of the 19th century until the early days of quantum physics. (shrink)