"The empiricist thinks he believes only what he sees, but he is much better at believing than at seeing." - George Santayana
I learned this quote from a class I'm taking this semester. Professor J. Edward Russo (also the author of the book Winning Decisions) gave an example in the class.
A new product development team observes a consumer focus group to discuss a new product concept. After the discussion, those who were positively predisposed on product development the team were more favorable after observing the consumer reaction. And those who were negatively predisposed were more opposed after observing the consumer reaction.
Why? As the other quote by Johann Wolfgang von Goethe, "A person hears only what they understand." Seeking only confirming evidence can turn a window into a mirror.