Demography originated by reason of development of empirical approach in science and it has been closely connected with statistical methods from the very beginning. A strong position of methodology in demography and poorly developed demographic theory are explained by that. The process of demographic study starts in contradistinction to many other empirical domains from preparation of demography subject with the aid of statistical description and only then it comes to its closer examination. A basic part of information about reality vanishes in the preparation process and an important position of demographic analysis in demography is explained by that. From the point of view of development principle — on which hither to existing science clas...