In this article, we redefine classical notions of theory reduction in such a way that model-theoretic preferential semantics becomes part of a realist depiction of this aspect of science. We offer a model-theoretic reconstruction of science in which theory succession or reduction is often better - or at a finer level of analysis - interpreted as the result of model succession or reduction. This analysis leads to 'defeasible reduction', defined as follows: The conjunction of the assumptions of a reducing theory (...) T with the definitions translating the vocabulary of a reduced theory T' to the vocabulary of T, defeasibly entails the assumptions of reduced T'. This relation of defeasible reduction offers, in the context of additional knowledge becoming available, articulation of a more flexible kind of reduction in theory development than in the classical case. Also, defeasible reduction is shown to solve the problems of entailment that classical homogeneous reduction encounters. Reduction in the defeasible sense is a practical device for studying the processes of science, since it is about highlighting different aspects of the same theory at different times of application, rather than about naive dreams concerning a metaphysical unity of science. (shrink)

If the defenders of typical postmodern accounts of science (and their less extreme social-constructivist partners) are at one end of the scale in current philosophy of science, who shall we place at the other end? Old-style metaphysical realists? Neo-neo-positivists? ... Are the choices concerning realist issues as simple as being centered around either, on the one hand, whether it is the way reality is “constructed” in accordance with some contingent language game that determines scientific “truth”; or, on the other hand, (...) whether it is the way things are in an independent reality that makes our theories true or false? If, in terms of realism, “strong” implies “metaphysical” in the traditional sense, and “weak” implies “non-absolutist” or “non-unique”, what – if anything – could realism after Rorty's shattering of the mirror of nature still entail? In accordance with my position as a model-theoretic realist, I shall show in this article the relevance of the assumption of an independent reality for postmodern (philosophy of) science – against Lyotard's dismissal of the necessity of this assumption for science which he interprets as a non-privileged game among many others. I shall imply that science is neither the “child” of positivist philosophy who has outgrown her mother, freeing herself from metaphysics and epistemology, nor is science, at the other end of the scale, foundationless and up for grabs. S. Afr. J. Philos. Vol.22(3) 2003: 220–235. (shrink)