Gottlob Frege (1848-1925) taught at the University of Jena for thirty years, and was scarcely known outside a small circle of professional mathematicians and philosophers. However, later in the twentieth century he came to be recognized as someone who, in demonstrating the affinity of logic with mathematics, laid the foundations for modern philosophy of language and modern logic. Frege regarded logic as the foundation for philosophy. In doing so, he instigated a radical change in the stance of the majority of Western philosophers whose main pre-occupation since Descartes had been the nature of knowledge rather than logic. His influence can be clearly seen in the work of local positivists of the early twentieth century, as well as in much of Ludwig Wittgenstein's philosophy. This impressive collection brings together recent scholarship on Frege, including new translations of German material, made available to Anglophone scholars for the first time.