In this autobiographical sketch, which is followed by a bibliography of my writings, I try to relate my intellectual development to problems, ideas and results in proof-theoretic semantics on which I have worked and to which I have contributed.

This paper is an investigation into what could be a goodexplication of ``theory S is reducible to theory T''''. Ipresent an axiomatic approach to reducibility, which is developedmetamathematically and used to evaluate most of the definitionsof ``reducible'''' found in the relevant literature. Among these,relative interpretability turns out to be most convincing as ageneral reducibility concept, proof-theoreticalreducibility being its only serious competitor left. Thisrelation is analyzed in some detail, both from the point of viewof the reducibility axioms and of modal logic.

Summary The concept of unified theory is defined in logical and abstract semantic terms, and employed in the analysis of relations between empirical scientific theories. The conceptual framework of the approach applies to binary relations such as the reduction or replacement of one theory by another, and to multiple intertheory relations. Historically, unified theories tend to arise within the contexts of scientific conflicts which they may show susceptible of solution even in the most controversial cases of the logical incompatibility or (...) conceptual incommensurability of competing theories. These conclusions are exemplified by the Planck-Einstein quantum theory of thermal radiation. The analysis shows in which sense it can, and in which it cannot, be said that this theory unifies Wien's law and the Rayleigh-Jeans law of black-body radiation. (shrink)

Thoroughgoing relativists typically dismiss the realist conviction that competing theories describe just one definite and mind-independent world-structure on the grounds that such theories fail to be relatively translatable even though they are equally correct. This line of argument allegedly brings relativism into direct conflict with the metaphysics of realism. I argue that this relativist line of reasoning is shaky by deriving a theorem about relativistic inquiry in formal epistemology—more specifically, in the approach Kevin Kelly has dubbed “logic of reliable inquiry”. (...) According to the theorem, two scientists, who share some background knowledge but follow different appropriately reliable methods, will converge to relatively formally translatable competing theories, even if meaning, truth, logic and evidence are allowed to vary in time depending on each scientist’s conjectures, actions, or conceptual choices. Some final remarks on the relevance of the theorem to the incommensurability thesis that has vexed twentieth century philosophy of science are adduced. (shrink)