An incredibly fascinating area of psychology that any scholar should consider is the theory called cognitive dissonance, formulated by L. Festinger in 1957. 

Cognitive dissonance therefore is the mental conflict resulting from holding two incompatible cognitions: beliefs, attitudes, or behaviors. This psychological state makes a person adjust the attitudes beliefs or behavior in order to elimination the experienced discomfort. For instance, if a person has the belief of the protection of the environment yet, he often uses a large colossal car, then, you can realize that he or she has this kind of conflict. To deal with this, they rationalize the behaviour arguing that it is necessary to drive the car or pursue other environmentally friendly activities like using a bike, or purchasing the environmentally friendly hybrid car. Decision making and change in attitude is supported by the theory of cognitive dissonance. It brings out why persons may justify or alter their attitudes due to psychological discomfort. It also reveals the role of rationalization of self in the view of highly powering up the self-esteem even after making decisions, which one can label as unethical.