rationalization

In psychology, rationalization is a defense mechanism where a person substitutes a safe and reasonable explanation for the true, but threatening, cause of their behavior. This is an unconscious mental process that helps individuals avoid anxiety or lower self-esteem by concealing internal drives or feelings.

For example, someone might rationalize buying a new car by saying it's more fuel-efficient, when the real reason might be a desire for a new possession. Other defense mechanisms include repression, reaction formation, projection, regression, sublimation, and denial. These are considered normal personality functions, though excessive use can be characteristic of psychological disorders.1