This report considers the differences between the medical psychiatric and the psychotherapeutic (in particular, the psychodynamic) approaches to the diagnostics and treatment of mental disorders, and it describes a generalized model of the psychotherapeutic process. It traces the development of the relationship between the medical psychiatric and the psychotherapeutic approaches, which has resulted in different models of the interrelatedness of these paradigms in different countries (a unified model encompassing both the psychiatric and the psychotherapeutic approaches, and a model of two relatively independent approaches). Examples are provided of the difficulties and inconsistencies which have arisen from attempts to employ different variants of the unified model that purports to unify the two different approaches into a single whole. It is proposed that the medical psychiatric and the psychotherapeutic approaches should each be considered to have their own internal logic, independent from and simultaneously complementary to that of the other, in accordance with the principle of complementarity formulated by the physicist Niels Bohr in quantum mechanics for the systematization of irreconcilable data obtained by observers with differing perspectives. The author proposes that each patient with a mental disorder should be examined simultaneously and independently from the point of view of each of these systems of coordinates (the medical psychiatric paradigm and the psychotherapeutic paradigm).