The eighth man rule

"It is the job of the 8th man to disagree with the rest." - Unknown

Paraphrasing a quote I heard in a movie or series long ago and haven't found again ever since. It was a woman talking to a man, she was probably referring to a jury or something similar. 

Basically it means one of their group was tasked to always disagree with the majority, even if he was the only person to disagree. This would help the entire group to always see things from a different perspective. I really liked this quote because I try to live by the idea of "thinking outside of the box".