Based on the results of our research, we present the mechanisms of population changes, explain their causes and indicate possible consequences. We responded to such initiatives as “Demographic Strategy 2040. Project” prepared by the Ministry of Family and Social Policy and the draft act on the Polish Institute of Family and Demography submitted by a group of members of the Law and Justice Parliamentary Club. The above opinions are presented in the text. The proposal of the Demographic Strategy focuses on fertility. In fact demographic development is reduced to low fertility without taking into account other components of the population reproduction as mortality, health and migration. While these demographic processes are closely interrelated and cannot be analysed separately when considering about the demographic future. The parliamentary draft contains beautiful intentions indicating the need for demographic research and analysis, but it devotes just one paragraph to scientific research. The document does not refer to institutions conducting demographic research in the country, neither in international cooperation, nor to insufficient financing of this research in Poland.