What is the Instinct Theory
Within the id, Freud proposed the existence of two basic instincts, relating to the themes of life and death. The more important of the two, especially in terms of personality development, is the life instinct or Eros. Freud viewed Eros as a life-enhancing and pleasure-oriented force, principally (though not exclusively) sexual in nature.Â The energy deriving from this instinct is termed libido. The death instinct, Thanatos, plays a role more in the speculative aspects of Freud’s later work.Â The ultimate goal of Thanatos (a term used by Freud in conversation, but not in his writings) is a return to the stability of inorganic matter.Â Its derivatives are aggression and destruction, but its energy was never labelled by Freud (though Rycroft  refers to later terms such as “destrudo” and “mortido”).
Instincts are suggested to have four main features. Firstly, an instinct requires a source, which is always biological. Physical energy supplied by the metabolic processes of the body is converted, by means not fully understood, into psychic energy. Secondly, an instinct will have an impetus – a force of strength – which is directly proportional to the underlying deficit, irritation or excitation. Thirdly, an instinct must have an aim, which is, generally, satisfaction, tension-reduction or wish-fulfilment, returning the person to a state of quiescence (or, to use a physiological term, homeostasis). Finally, an object is required to satisfy this aim.Â Object refers not only to the “thing” towards which action is directed, but to all activity intervening between wish and fulfilment. To illustrate these four features, the sex instinct hasÂ a physical source of excitation, an impetus or intensity of excitation, an aim to achieve sexual gratification, and an object comprising (in mature sexuality, according to Freud) sexual union with an adult member of the opposite sex.
Source, impetus and aim remain relatively constant throughout life.Â Since psychic energy is displaceable, however, there is considerable variation in object-choice.Â Such displacement is perhaps the most important factor in personality development and dynamics, accounting for the enormous diversity of human nature. All attributes, preferences and behaviour reflect displacements of energy from original object-choices.