Gottlob Frege
German mathematician, logician and philosopher (1848–1925), born in Wismar, a professor throughout his career at the modest University of Jena, where he worked in near-total intellectual isolation, little recognised and barely read by his contemporaries, despite producing a body of work now universally regarded as foundational for all of modern logic and analytic philosophy of language. His work Begriffsschrift (1879), a radically new notational system based on two-dimensional formulas, marked the development of the first fully formalised first-order predicate logic in history, decisively surpassing the limitations of Aristotelian syllogistic logic that had dominated Western thought for over two thousand years, and laying the technical foundations for all of modern mathematical logic. His most ambitious philosophical project, set out in The Foundations of Arithmetic (1884) and developed technically in the two volumes of Basic Laws of Arithmetic (1893, 1903), was 'logicism': the attempt to show that all mathematics, and arithmetic in particular, could be derived purely from logical principles and definitions, without recourse to Kantian spatio-temporal intuition or empirical experience. This ambitious project suffered a devastating blow just as the second volume of Basic Laws was about to go to press: Bertrand Russell sent him a letter in 1902 revealing the paradox that bears his name, demonstrating a fundamental contradiction in Frege's axiomatic system, an event Frege himself acknowledged with exemplary intellectual honesty in a note hastily added before publication. Philosophically, Frege also developed the crucial distinction between 'sense' (Sinn) and 'reference' (Bedeutung), formulated in his celebrated essay On Sense and Reference (1892), which explains how two expressions can refer to the same object (the 'morning star' and the 'evening star', both referring to Venus) while possessing different cognitive meanings, a foundational distinction for all twentieth-century philosophy of language. Belatedly rediscovered by Bertrand Russell and Ludwig Wittgenstein, Frege is today regarded, alongside them, as one of the undisputed founding fathers of contemporary analytic philosophy.