The paper discusses two viewpoints on the usage of scientific theoretical ideas within the context of psychotherapy based on humanities. There are authors who believe that no psychotherapist can go without theoretical conceptions, and others who disagree with this position (in relation to the latter viewpoint the phenomenological approach of A. Puzyrei is reviewed). The author, an adherent of the first position, analyzes the work of P. Volkov that makes use of theoretical concepts of psychology and philosophy. He shows that theoretical notions provide a conceptual space that enables the creation of “therapeutic constructions” that can not be deduced from the theory but have to fit with it. Volkov’s approach is compared to the approach of G. Nardone that is currently popular among therapists, and it is shown that methodologically they are very close. The final part of the paper presents the principles of the theory of mental realities developed by the author who believes that this theory may help psychotherapists drawing from humanities to widen the scope of their scientific notions.