Freud’s theory initially described a class of drives known as the life instincts and believed that these drives were responsible for much of behavior. Eventually, he came to believe that these life instincts alone could not explain all human behavior. Freud determined that all instincts fall into one of two major classes: the life instincts or the death instincts.
Life Instincts (Eros)
Sometimes referred to as sexual instincts, the life instincts are those that deal with basic survival, pleasure, and reproduction. These instincts are important for sustaining the life of the individual as well as the continuation of the species. While they are often called sexual instincts, these drives also include such things as thirst, hunger, and pain avoidance. The energy created by the life instincts is known as libido.
Behaviors commonly associated with the life instinct include love, cooperation, and other prosocial actions.
Death Intincts (Thanatos)
Initially described in his book Beyond the Pleasure Principle, Freud proposed that “the goal of all life is death” (1920). He noted that after people experience a traumatic event (such as war), they often reenact the experience. He concluded that people hold an unconscious desire to die, but that this wish is largely tempered by the life instincts.
In Freud’s view, self-destructive behavior is an expression of the energy created by the death instincts. When this energy is directed outward onto others, it is expressed as aggression and violence.