" It is always useful to think badly about people one has exploited or plans to exploit. Modifying one’s opinions to bring them into line with one’s actions or planned actions is the most common outcome of the process known as “cognitive dissonance,” according to social psychologist Leon Festinger. No one likes to think of himself or herself as a bad person. To treat badly another person whom we consider a reasonable human being creates a tension between act and attitude that demands resolution. "

― James W. Loewen , Lies My Teacher Told Me: Everything Your American History Textbook Got Wrong