1 1 2 D O C . 9 6 R E V I E W O F R E I C H E N B A C H 96. Review of Reichenbach’s Philosophie der Raum-Zeit-Lehre [Einstein 1928d] Dated after 1 December 1927 Published 1928 In: Deutsche Literaturzeitung 1 (1928): col. 19–20. Hans Reichenbach [adjunct prof. of philos. at the Univ. of Berlin], Philosophie der Raum-Zeit-Lehre, Berlin & Leipzig, Walter de Gruyter & Co., 1928. 323 pp. 8°, M.18.— [1] Reichenbach’s book treats the science of space and time from the point of view of the theory of knowledge insofar as they enter into physics. It thus deals with space and time as such, in the sense that these two conceptual aggregates serve as ordering principles within that which is thought of as “reality.” It is difficult to say something fundamentally new about such general matters, unless it is in connection with new conceptual constructions in physics. As such, the most recent attempts of quantum theory would be relevant,[2] but they are not yet dealt with by the author and quite rightly,[3] for a treatment from the viewpoint of the theory of knowledge would be appropriate only after this stage of develop- ment is essentially completed.[4] Thus, for the analysis intended by the author here, apart from classical physics, only the new aspects introduced by relativity theory can be considered.[5] Within the framework thus defined, the object is treated clearly, thoroughly, and independently.[6] The author distinguishes sharply between conceptual systems (pure mathemat- ics), that are based exclusively on “implicit definitions,” whose laws can be cor- rectly developed only through pure logic, but have no relationship to reality and those conceptual systems that have a claim to “truth,” i.e., which make statements about the real world. The relation of a conceptual system to the world of “reality” is accomplished through an “attribution definition.” This is an indication of its con- tent: which sort of an experiential object should correspond to a given concept. The clear elaboration of the attribution definition, in particular in the field of relativity theory, is one of the principal goals that the author has set himself, and has attained. In the first section, which deals with space, I found the attempt to make spaces of non-Euclidean structure and their topological properties accessible to intuitive understanding particularly interesting. The theory that Euclidean geometry is [p. 19] [p. 20]