"A man with a conviction is a hard man to change. Tell him you disagree and he turns away. Show him facts or figures and he questions your sources. Appeal to logic and he fails to see your point. We are familiar with the variety of ingenious defenses with which people protect their convictions, managing to keep them unscathed through the most devastating attacks.
"...Suppose an individual believes something with his whole heart; suppose futher that he has a commitment to this belief and he has taken irrevocable actions because of it; finally, suppose that he is presented with evidence, unequivocal and undeniable evidence, that his belief is wrong: what will happen? The individual will frequently emerge, not only unshaken, but even more convinced of the truth of his beliefs than ever before. Indeed, he may even show a new fervor for convincing and converting other people to his view."
-- Leon Festinger, When Prophecy Fails (1956)
"Psychological experiments have shown that humans tend to seek out even weak evidence to support their existing beliefs, and to ignore evidence that undercuts those beliefs. In the process, we apply stringent tests to evidence we don't want to hear, while letting slide uncritically into our minds any information that suits our needs."
--Brooks Jackson and Kathleen Hall Jamieson, The Wisdom of Crowds
page by Geoffrey A. Landis, 2011.