You've heard of Galileo, right? He was the guy who went against astronomers of the time, as well as public opinion, and insisted that the earth was not the center of the universe. After a life of persecution, in the end it turned out that he was right.
You probably haven't heard of Lindi or Jonah who go against public opinion claiming that Elvis is still alive and living on the planet Hounddogian, in the constellation Bluesuede. When questioned about their odd beliefs, Lindi and Jonah confidently reply, "You know, people thought Galileo was nuts, too."
While you don't know Lindi or Jonah, you most likely know of people like them who hold bizarre beliefs and call upon the "Galileo Defense" to validate their own reasoning ability and cause you to doubt yours. Remind yourself, and these people, that for every Galileo, there are millions of cranks, quacks, and wackos, and statistically speaking, they are one of the latter.