Gottlob Frege

The creator of modern logic was born in the Pomeranian town of Wismar. His father was headmaster at a school for young ladies, which Frege's mother took over after her husband's early death. Frege studied mathematics at the University of Jena. His studies were encouraged by Ernst Abbe, who encouraged him to obtain a doctorate at Gottingen and then helped him secure a position as lecturer at Jena in 1874. Although trained as a mathematician, Frege also studied with Lotze at Gottingen, and his work shows the influence of both Leibniz and Kant. After the publication in 1879 of Frege's first important work, the Begriffschrift (Conceptual Notation), he was promoted to professor, and he remained at the University of Jena the rest of his life. The Begriffschrift was the basis of his new system of logic, which he then sought to apply to the task of deriving number theory entirely from logic, via the theory of classes. This he did in The Foundations of Arithmetic (1884).

The next decade saw several of Frege's other important papers on the philosophy of logic and language, including "Function and Concept" (1891), "Concept and Object" (1892), and "Sense and Reference" (1892). Frege was an extreme critic of "psychologism" in logic, mathematics, and philosophy of language---that is, of any view that attempts to treat logic or other sciences pursuing necessary truth as sciences whose subject matter is the actual functioning of the human mind as it can be empirically observed. His critique of psychologism had a far-reaching impact on philosophy in the twentieth century, strongly influencing the development not only of logical positivism and analytical philosophy in English-speaking countries, but also of neo-Kantianism and the phenomenological movement on the continent.