This chapter argues that the early Bertrand Russell was very much connected to the post-Kantian tradition of logic that included methodology. It shows that Russell’s work in the 1910s on the conceptual foundations of the empirical sciences—specifically the projects surrounding and including his 1914 Our Knowledge of the External World—emerged out of methodological concerns that he had developed already in his idealist period of the 1890s. The chapter aims to place Russell within the broader movement of scientific philosophy, which includes philosophers of a variety of traditions including phenomenology, neo-Kantianism, and early analytic philosophy. It examines Christoph Sigwart’s philosophy and presents some of the general features of scientific philosophy that he holds to, especially a renewal of cooperation between philosophy and the sciences. The chapter discusses some of the more particular features of his philosophical project, key among them his focus on the methodology of the sciences.