Danish body of Geiger's work has been translated (commented version) to German by Gert J. Fode of the University of Aarhus, edited by Prof. Klaus Rodax (University of Erfurt, Germany). Methodology Geiger made many significant contributions to methodology of the social sciences. Seeing no necessary difference between the laws and methods of the natural sciences and those of the social sciences, he advocated for unity of the methodologies of all the empirical sciences. Geiger believed that sociology can only be a true scientific discipline if it establishes this consistent methodology and a rejection of the idiographic approach. Further, sociology should not study isolated instances, but rather patterns. This requires iterating between the general and the specific, by alternatively adopting catascopic and anascopic approaches. Geiger stressed the importance of supporting inductive research with empirical data but also the importance of theory in the analysis of empirical evidence. He believed that concepts are not to be derived from observation and experience alone but must be supported by them. The professor in Philosophy at the University of Aarhus, Svend Ranulf, at the time of Geiger's professorship there in Sociology, wrote a textbook about social science methodology, making arguments against some social scientists' methodologies. In particular, he argued against Geiger. Ranulf had been an applicant for the professorship position that Geiger was awarded in 1938. Ranulf alluded in his textbook that the methodologies of some sociologists, among them Theodor Geiger, could lead to a new Nazi movement. In 1946 Geiger wrote and published a short book, "Ranulf Contra Geiger, an Attack and an Offensive Defense". In this book, Geiger outlined very carefully what his methodologies were, emphasizing that empirical sociology is built on concepts but is a quantitative study of social processes and phenomena. He validated one point made by Ranulf, that data should be collected in a non-biased way but he also defended that concepts come prior to data collection in research, and although such concepts may need revision after collection of data is through, any data collection without a conceptual foundation is illogical. In response to Ranulf's opposition to qualitative data and interpretation, Geiger argued that these were okay for analysis as long as the researcher maintained a value-free approach. Geiger published several articles in 1948 and 1949 about his theoretical considerations of methodology. Thought Social Stratification and Mobility Social Stratification and Social mobility were included among Geiger's main interests and within