Rationalization in Psychology is a defense mechanism, which involves the justification of an unacceptable behavior, thought or feeling in a logical manner, avoiding the true reason for the action. It is encourages irrational or unacceptable behavior, motives, or feelings and often involves ad hoc hypothesizing. It is used to great comic effect in Candide: Or, Optimism, the satirical masterpiece of the 18th century Enlightenment thinker Voltaire. The term Rationalization in Psychology identified by Sigmund Freud.