ALBERT

Notes: Abstract Although this article is self-contained, the ideas developed herein continue the discussions in the author's book The Structure and Dynamics of Theories (New York 1976). In an introductory section, a brief description is given of the structuralistic or non-statemental view of theories. Physical theories are introduced as nets of ordered pairs, each pair consisting of a sequence of mathematical structures and a class of domains of application. Following J. D. Sneed, a theory is thereby distinguished from its hypotheses or empirical claims. By virtue of the occurrence of terms which are theoretical with respect to the given theory, the whole empirical claim of a theory at a given time must be formulated as one single sentence. In a third step, it is explained what it means to say that a person holds a theory at a given time. This pragmatic concept can serve as a starting point of analyzing certain aspects of theory change. In particular, the idea of a ‘normal science’ in the sense of Kuhn, as well as the idea of a ‘progressive research program’ in the sense of Lakatos, can be rendered precise. In order to explain what ‘revolutionary progress’ means, a new intertheoretical relation is needed. It is suggested that explication of the progressive character of a scientific revolution be made with the help of the relation of approximative embedding of the displaced theory into the supplanting theory. The resulting concept of scientific progress thus stands in strong opposition to all teleological conceptions of progress. This becomes manifest by the fact that it admits of progress branchings, thereby justifying the picture of the ‘evolutionary tree’ and emphasizing important role of decisions and value judgements in scientific progress. History and Philosophy of science can be brought into still closer contact by means of concepts referring to paradigmatic objects, paradigmatic dispositions and several aspects of scientific communities. Enclosed in the topics of the discussion are the socalled theory-ladenness of observations, the thesis of holism and the problem of scientific rationality. Furthermore, it is argued that the concept of a rational reconstruction in terms of methodological rules should be abandoned, and that the misleading term ‘methodological rule’ be replaced by the liberally interpreted phrase ‘methodological recommendation’.