The article studies theoretical and methodological approaches of subjective and objective idealism, General scientific subjective and consumer methodological approaches, analyzes the scientific positions of economic schools of mercantilism and marginalism, considers the views of the economic school of physiocrats, the ideology of objective rationalism of classical political economy. In the course of theoretical research, the process, tendency and regularity of transformation of the main principles of subjective and objective idealism into the basic characteristics of consumer and system methodological approaches, which are the basis for evaluating the economic efficiency of investment projects, are established.