There are a number of theories to explain this phenomenon: Psychoanalysts, following Freud, speak of a death instinct; some feel this works as an efflux from the powers of the root psychic force, the libido. To other analysts it is an energy in its own right, the destrudo; while again for others, the self-directed destructive energy is distinguished as the mortido: this is supposed by some to be biologically situated although triggered by physical or mental reactions to what the organism perceives as deep-level pain, and thus constitutes an escape hatch. Others deny the biology, and say it is not an instinct but a psychological drive arising with the development of the individual psychic structure. Still other analysts suspect a positive purpose to what might be termed, self-reducing, or self-limiting tendencies in the psyche.
There is considerable confusion of both terminology and conceptualization in this subject, and the observable facts of physical deterioration in its natural phase, [viz] senescence, and its attendant mental, emotional and social factors, are not adequately included. In the analytical psychology of Jung some emphasis was given to this phase as the field upon which the final maturation or integration of the personality could be played. The accord of the psyche with physical dissolution is seen as a therapeutic process from this viewpoint. Since the physical condition of senescence may trigger the first thoughts of death, the biological alarm clock in the body also may go off at an earlier hour, a carry-over or atavism of the not-so remote times when, following millions of years of evolution, Homo sapiens died at one-half or less of the age attained now. This helps to account for the severity of middle-age depression or crisis which can strike before the age of forty or as late as the middle fifties. Other biological causes for 'death instincts' may be disease of the organism. Social reasons for an individual's proclivity for self-destruction may be societal and family 'disease'.
The death wish shows itself in many ways: (a) suicide; (b) psychogenic death, or the surrender of the will to live; (c) murder, the murderer kills in order to be killed; (d) in war, a way of committing suicide is provided without the moral or religious guilt attached to it; (e) in certain philosophical, religious and political beliefs, such as atheism, agnosticism, humanism, existentialism nihilism and anarchism; (f) the choice of death-defying professions, such as mountain climbing, automobile racing, sky diving, and parachuting; (g) insanity veils full consciousness with its burdening responsibility; (h) sickness where many patients do not want to get well; (i) addictions to drugs and alcohol; (j) bad luck and accident proneness; and (k) pleasure which can also be a way of escaping the hard realities of life.
Without the death urge, the drive to live would not exist. Until a person has come to terms with their own death, not some symbolic abstraction but the reality of rotting in the grave, they have not really lived. Coming to terms with the reality of death is not simply acknowledging it but personally forcing one's death to reveal the meaning of one's life. Without the death urge one's life has no authenticity.