 Logical empiricism’s philosophy of science was conceived under the guiding star of Einstein’s two theories of relativity, as may be seen from the early writings of its founders, for purposes here, Moritz Schlick, Rudolf Carnap, and Hans Reichenbach. A small monograph of Schlick, Space and Time in Contemporary Physics, appearing in 1917 initially in successive issues of the scientific weekly Die Naturwissenschaften, served as prototype. One of the first of a host of philosophical examinations of the general theory of relativity, it was distinguished both by the lucidity of its largely non-technical physical exposition and by Einstein’s enthusiastic praise of its philosophical appraisal, favoring conventionalism à la Poincaré over both neo-Kantianism and Machian positivism. The transformation of the concept of space within the general theory of relativity was the subject of Rudolf Carnap’s dissertation at Jena in 1921. Appearing as a monograph in 1922, it also evinced a broadly conventionalist methodology combined with elements of Husserlian transcendental phenomenology. Distinguishing clearly between intuitive, physical and purely formal conceptions of space, Carnap argued that, subject to the necessary constraints of certain a priori phenomenological conditions of the topology of intuitive space, the purely formal and the physical aspects of theories of space, can be adjusted to one another so as to preserve any conventionally chosen aspect. In turn, Hans Reichenbach was one of five intrepid attendees of Einstein’s first seminar on general relativity given at Berlin University in the tumultuous winter of 1918–1919; his detailed notebooks survive. The general theory of relativity was the particular subject of Reichenbach’s neo-Kantian first book (1920), which is dedicated to Albert Einstein, as well as of his next two books (1924, 1928), and of numerous papers in the 1920s.