In three comprehensive volumes, Logic of the Future presents a full panorama of Charles S. Peirce's most important late writings. Among the most influential American thinkers, Peirce took his existential graphs to be his most significant contribution to human thought. The manuscripts from 1895-1913, most of which published here for the first time, testify the richness and open-endedness of his theory of logic and its applications. They also invite us to reconsider our ordinary conceptions of reasoning as well as the conventional stories concerning the evolution of modern logic. Peirce's 1904-1908 writings on pragmaticism define his mature philosophy, grounded upon the principles of logical analysis as provided by existential graphs. This third volume of the series includes a comprehensive selection of letters exchanged from 1898-1913 between Peirce and his colleagues and collaborators on the logic and philosophy of existential graphs.