In conditions of limited financial resources of the state, the task of assessing the appropriateness and choosing rational options for the joint use of traditional and new types of high-tech products is topical. The paper proposes a method for substantiating rational options for the joint use of traditional and new products of high-tech products, based on the criteria of their comparative technical and economic assessment, namely, comparing the achieved efficiency and the required cost of performing a fixed set of tasks. The dialectical foundations of the method are presented, in particular, it is established that the law of development of high-tech products fully corresponds to the well-known classical law of «denial of denial». The structure of the method, the order of formation of the set of Pareto-optimal options for the joint use of traditional and new products, as well as the algorithm for choosing a rational option are considered.