The article presents an analysis of the endoteric basis of the concept, developed by the author, of the theoretical economy. In the author’s view, this basis is provided by the development of classical political economy in its highest expression, Marxism. The article stresses the priority role of classical political economy within the framework of the above-mentioned concept as a tool for investigating the substantive aspects of the categories under study. The author considers that at the same time, the function of examining only the forms, taken in isolation, in which these categories manifest themselves belongs to neoclassical and institutional methodologies. In such a capacity, the concept of the theoretical economy positions itself as a new paradigmatic mainstream in socio-economic research.