This article is about social philosophy. For externalization (of cost), in the context of economics, see externality.
Externalization means to put something outside of its original borders, especially to put a human function outside of the human body. The opposite of externalization is internalization.
In a concrete sense, by taking notes, we can externalize the function of memory which normally belongs in the brain.
In a more abstract sense, by making excuses, we can externalize the guilt associated with our actions.
In Freudian psychology, externalization is an unconscious defense mechanism, where an individual "projects" his own internal characteristics onto the outside world, particularly onto other people. For example, a patient who is overly argumentative might instead perceive others as argumentative and himself as blameless.
Like other defense mechanisms, externalization is a protection against anxiety and is, therefore, part of a normal, healthily-functioning mind. However, if taken to excess it can lead to the development of a neurosis.
Externalization can also be used in the context of a corporation. A corporation that externalizes its costs onto society and the environment is not taking full and proper responsibility and ownership of these costs. For example, untreated toxic waste being discharged into a river where people wash and fish.
^ Sandler, Joseph (1988). Title Projection, identification, projective identification. Karnac Books. ISBN 0-946439-40-0.