The article deals with the first publication of a chapter of manuscript “The General Methodology of the Humanities” by Nikolay I. Kareev - historian, sociologist, and theorist. This general study was written in the late 1910s - early 1920s and was planned for publishging in the “Mysl” publishing house in Petrograd, however it was not done. The book is based on the positivistic approach, but also it has the traces of contemporary theories as Neo-Kantianism. The author focuses on the problem of elaboration of the investigation method, which was common for both scientists and scholars, and methodology of the Humanities as its part. In published chapter N. Kareev deals with the problem formation of empiric basis for the Humanities and how it differs from scientific empirics - the method of observation and statement particularly. The authors come to the conclusion that N. Kareev, studying features of observation in social sciences, admits the complex nature of historical and social facts and arrives at conclusion concerning the necessity of developing the theory of source criticism. The publication of the chapter gives an opportunity to criticize Kareev’s approach and to compare it with contemporary scientific criterion. The scholar notes the contradiction of precision and complexity in social sciences and reinterprets the case of observation and source criticism. The text of the fourth chapter of the manuscript “General Methodology of the Humanities” is published according to the autograph discovered in his archives of the Scientific Manuscript Department of Russian State Library.