Appeal to tradition

"This is right because we've always done it this way." The appeal to tradition is a very common logical fallacy in which someone proclaims his or her accuracy by noting that "this is how it's always been done."

The assumption behind this argument is that whatever reason led to the old methods of thinking is still valid today. If circumstances have changed, this may be a false assumption.

Examples:

"It's always been done that way. We've never done it like that."

"You're crazy! Nobody ever thought like that before!"

"This precedent was set 100 years ago and has been followed many times."

The opposite is the appeal to novelty, claiming something is good because it's new.