Sigmund Freud, and later Anna Freud, assigned to the ego tasks that involve the management of instincts and defenses against them. Some of their successors, among them Robert Waelder (1936), treated these tasks as "functions" that the ego was expected to fulfill. Thus such functions as integration, synthesis, and so on, were eventually distinguished. According to Heinz Hartmann, the ego should be evaluated according to how it performs these functions.
It is hard to say what the primitive function of the ego might have been, but, historically speaking, self-preservation is not only a function of the ego but also an instinct in its own right, originating in the ego—in short, an ego instinct. Freud first presented the concept of an ego instinct in Beyond the Pleasure Principle (1920g), where he also developed his theory of the death instinct. Briefly, the instinct for self-preservation can be subdivided into positive tendencies governed by the libido or Eros and negative tendencies subject to the death instinct. This account of the functions of the ego, which Freud himself always considered to be only a speculative hypothesis, was never accepted by more than a handful of analysts, even among those who granted the existence of aggressive and destructive instincts.
In the psychoanalytical ego psychology of 2005, these issues have ceased to carry much weight. The ego described in terms of its functions is no longer envisaged in the same way. True, Anglo-American psychoanalysis recognizes the notion of the death instinct, but the Anglo-American use of it is somewhat different from Freud's.
One essential function of the ego, according to Freud, is to synthesize all the impulses and energies of body and mind. This synthesis depends entirely on the strength of the two psychic forces of the libido and the destructive, or death, instinct. To begin with, Freud (1930a, p. 117) had adopted Friedrich Schiller's antithesis of love and hunger, with love being equivalent to the libido and hunger standing for the self-preservation instinct. During the 1920s Freud replaced this idea by postulating the ego's synthetic function.
Another important ego function was defense and the signaling of danger. Danger might come from within (from the id), from without (from reality), or even from the superego. Against these threats the ego could defend itself in a variety of ways, depending on the individual. Among the ego's defensive functions were identification with the aggressor, forgetting, disavowal, and repression. Recognition, reflection, and above all action were also ego functions, yet the ego could feel pain, as in states of mourning or joy, and thus serve as vector of the emotions. The body ego, as the locus where instinctual impulses are discharged, was liable to come under the sway of the instincts, which could lead to brief depressions or to chronic mental illness.
Freud held that as a general rule the ego was the dominant mental agency, so long as it was functioning normally. Ego malfunction, in contrast, led to deep anxiety, and the weaker the ego the greater the anxiety. For this reason infantile anxiety was a normal state, whereas in adults it was a signal of danger. Its absence—loss of the feeling of anxiety—constituted a serious mental disturbance. Enumeration of the ego's functions pointed up the importance of the ego as an agency. Because it brought so many functions together, the ego was central to treatment and the nucleus of resistance. Freud recognized the ego as a major obstacle to psychoanalysis.
After Freud's death, ego psychology underwent considerable development, partly to the detriment of id psychology. This was a deviation in that when Freud set out on his research program, he was interested exclusively in unconscious mental life, in the depths of the mind, in a cauldron of energies that fulfilled no specific functions. Yet such energies are capable of modifying the ego in important ways, whether for good or for evil.
See also: Ego; Ego (ego psychology).
Freud, Sigmund. (1920g). Beyond the pleasure principle. SE, 18: 1-64.
——. (1930a). Civilization and its discontents. SE, 21: 57-145.
Hartmann, Heinz. (1956). The ego concept in Freud's work. International Journal of Psycho-Analysis, 37, 425-438.
——. (1958). Ego psychology and the problem of adaptation (David Rapaport, Trans.). New York: International Universities Press. (Original work published 1939)
——. (1964). Essays on ego psychology. New York: International Universities Press.
Waelder, Robert. (1936). The principle of multiple function: observations on over-determination. Psychoanalytic Quarterly, 5, 45-62.