This paper considers the charge that—contrary to the current widespread assumption accompanying the near-universal neglect of his work—Wilhelm Jerusalem (1854–1923) cannot count as one of the founders of the sociology of (scientific) knowledge. In order to elucidate the matter, Jerusalem’s “sociology of cognition” is here reconstructed in the context of his own work in psychology and philosophy as well as in the context of the work of some predecessors and contemporaries. It is argued that while it shows clear discontinuities with (...) the present-day understanding of the sociology of (scientific) knowledge, Jerusalem’s sociology of cognition was not only distinctive in its own day but also anticipated in nuce a much-discussed theme in current history of science. (shrink)

This article analyses three basic concepts of Ludwik Fleck’s Genesis and Development of a Scientific Fact. It shows first that Fleck’s notion of „directed perception“ is closely linked to Jakob von Uexküll’s writings on the „Umwelt“ of animals and humans. The article then proposes to regard the epistemological debates surrounding parapsychology as an important testing ground for the Fleckian concept of „mood“ and his concomitant hypotheses about „the tenacity of systems of opinion and the harmony of illusions“. It finally argues (...) that Fleck’s modification of Wilhelm Jerusalem’s idea of the „social consolidation“ of knowledge helps us to understand the indebtedness of Fleck towards early functionalist sociology as well as his strong belief in „specific historical laws governing the development of ideas“. The historical semantics of Fleck’s works hence proves that his insights are neither marginal nor revolutionary but rather deeply rooted within scientific traditions from the late 19th and early 20th centuries. (shrink)

Karl Eugen Müller's contribution to the development of the algebra of logic is perhaps the most important part of his scientific work. Müller, who became Gymnasialprofessor after his university studies, was a student of Ernst Schröder's friend, the mathematician Jakob Lüroth. As a result of publishing two papers on problems related to Schröder's monumental Vorlesungen iiber die Algebra der Logik, Müller was commissioned by the Deutsche Mathematiker- Vereinigung with the editing of the unpublished parts of the Vorlesungen from Schröder's Nachla?. (...) Müller worked on Schröder's papers until 1910, but did not bring this work to a conclusion. Müller's own Nachla?, including those parts of Schröder's papers still in his possession, was destroyed in Frankfurt a.M. in 1943, so there remains no hope of finding through Müller any part of the missing Nachla? of Schröder. (shrink)