Principle of Constancy
The principle of constancy is the principle of psychic functioning that seeks to maintain the quantity of excitation contained in the apparatus at a low or constant level. This is accomplished through a discharge of the energy present in the apparatus or by avoiding its augmentation.
In 1892, Freud submitted a manuscript and letter to Breuer articulating their common position regarding the thesis of "holding constant the amount of excitation" (1940d). One year later, Freud spoke of a tendency to "shrink" or "diminish" the "amount of excitation," and trauma was conceived to be a result of its augmentation.
The principle of constancy represented a point of view widely accepted in the sciences of the nineteenth century, such as Fechner's equilibrium principle (Laplanche and Pontalis, 1967; Laplanche, 1970). Its workings were held to be furnished by mechanisms (in the Freudian sense of acts and behaviors) of avoidance of external excitations, of defense and of discharge (abreaction) in response to increased tension of internal origin.
The principle of constancy is a central feature of the theory developed between 1892 and 1895, introduced in order to account for phenomena observed in hysteria that contradicted this "precondition of health" (1940d). From this point forward symptoms were blamed on a lack of abreaction, and treatment offered adequate discharge. However, Breuer envisaged the law of constancy as optimal, allowing for a free circulation of kinetic energy. In his "Project" of 1895 Freud sought a principle unrelated to healthiness, by sketching out an operation that occurred simultaneously at the heart of and at the extremities of a specific portion of the nervous system. The principle of constancy was thereby supplanted by an inertia principle, according to which certain neurons tend to empty themselves totally of their quantity of excitation. The tendency to constancy would become a secondary function—a modification of the inertia principle—demanded by the "exigencies of life." It is confined to the secondary processes of the "ego" where energy is bound, meaning maintained at a certain level in the "psi system."
In The Interpretation of Dreams (1900a) the opposition constancy/inertia serves as a backdrop. The principle of inertia regulated the functioning of the system Ucs. according to the laws of primary functioning. The principle of constancy worked at the level of the Pcs.-Cs. system through cathexes, diversion of inhibitions, and transformations into states of quiescence by raising excitation to even levels. Subsequently, the opposition between the two modes of functioning was most often assimilated to the opposition between the pleasure principle and the reality principle.
Freud finally formulated an explicit "principle of constancy" in Beyond the Pleasure Principle (1920g), as the economic basis of the pleasure principle, but he left open the question concerning what level should be aimed at: zero, constant, low, high, etc. However the tendency toward zero that later became the "Nirvana Principle" was considered fundamental. It was in this connection that Freud introduced the death drive. The latter tended toward the absolute reduction of tensions and was opposed to the life drive, which made use of heightened tension levels in its quest to forge and hold onto vital unities.
Freud's thinking on this matter remains plagued by an unresolved difficulty. Is psychoanalysis limited to a narrow domain, or does it represent an attempt to create a general psychology, meaning a biology? In spite of the "self-preservation/sexuality" distinction, the overlap between vitality and sexuality remained a problem for Freudian theory to work through. Was the energy Freud envisioned energy in general, or sexual energy (cf. Jung)? Did everyday regulatory mechanisms encompass the phenomena of increased quantities of all kinds, or was the augmentation of psychic sexual energy controlled by a special sub-regulatory mechanism?
The principle of constancy was the basis of the conception of the pleasure/unpleasure principle, but the latter's complexity (a pleasurable sensation may accompany an increase in tension), became increasingly evident to Freud, reopening the possibility of a confusion of the pleasure and constancy principles. The principle of constancy, which resembles the principle of homeostasis that Walter Bradford Cannon would later introduce, served as kind of general principle of self-regulation, whereas the specifically sexual pleasure principle can (and must) detract from this general principal. This was an inextricable complexity that the conceptualization, in 1920, of the life drive attempted to resolve.