The study of any psychological phenomenon in the cultural-historical tradition cannot be separated from the scientific reflection on the situation of development of the scientific knowledge about it, i.e., of the conceptual apparatus and the general logic of its development in the context of changing historical conditions. For the mentioned reason, a brief insight into the history of understanding of the phenomenon of psychological defense appears to be necessary.The notion 'defense mechanisms' emerged in psychoanalysis at the turn of the 20th century and was based on the dominant paradigm of natural scientific thought and positivism; later on it fell outside its limits and acquired polyvalence and blurriness, particularly due to phenomenological, humanistic, and cognitive traditions. Since Freud's first description (1895) of 'defensive actions' of repression in regard to the nature of hysteria and some other neuroses, as well as the analysis of 'the psychopathology of everyday life,' the theory of defense mechanisms (DMs) has been repeatedly revised after the changes in theory of personality, the rethinking of significance of social reality, culture, language and 'semiosphere' as the driving forces and the 'fields' of development of norm and pathology. That is why, when we analyze the phenomenon of DMs, we encounter the variety of frameworks elaborated in every scientific theory, which studies personality problems, and the diversity of views on the genesis, the structure and the functions of DMs. Therefore, here we could hardly offer a complete picture of phenomenology and conceptualization of psychological defenses.In the contemporary psychoanalytic literature DMs are defined in the most general form as Group of operations aimed at the reduction and elimination of any change liable to threaten the integrity and stability of the bio-psychological individual... Generally speaking, defense is directed towards internal (instinct); in practice, its action is extended to whatever representations (memories, fantasies) this is bound to; and to any situation that is unpleasurable for the ego as a result of its incompatibility with the individual's equilibrium and, to that extent, liable to spark off the excitation (Laplanche & Pontalis, 1996, p. 145). Putting aside the frameworks of specific theories, nowadays we also admit that any psychic phenomena or psychic processes are, in essence, capable of being stimulated by the motive of defense, if they occur in certain conditions (a conflict) and with a specific purpose (to end or alleviate anxiety). It appears reasonable to also speak about DMs as the sui generis 'functional organs' for adaptation to an inexplicit, unforeseen intrapsychic or interpsychic situation that potentially threatens the mind as a whole. They can both facilitate development and personality stability and lead to disorganization and maladjustment, depending on their internal structure, dynamics, level of cultural symbolic and social mediation and, consequently, their maturity.Despite the long history of research, the problem of psychological defense still remains controversial. Among the most acute issues we would like to emphasize the following: general patterns of formation and reorganization of DMs in ontogenesis; stimulating sources of generation of DMs (intra / interpersonal), functions (defensive / adaptive, destructive / constructive); levels of functioning (conscious / unconscious, emotional / cognitive); relation of DMs to other mechanisms of self-regulation; criteria of distinction between archaic (primitive) and relatively late, mature defenses; factors that determine individual typological variability of DMs; pathogenic role of primitive DMs in abnormal development. First of all, let us turn to the analysis of the evolution of ideas on DMs in the psychoanalytic context.The illustrious 'naturalisticity' of the first Freudian notions about the organismic (almost mechanical) organization of the mental apparatus that follows the biological 'vital rush' and the pleasure principle and is simultaneously forced to obey the reality principle, fully reflected the mentality of Freud as a doctor, a natural scientist and the successor of the Enlightenment. …