The Precautionary Principle

 "The clarity of a scientific conclusion exists along a spectrum from genuinely controversial to rock solid, but scientific evidence is always complex, subject to multiple interpretations, and incomplete. It doesn’t take much creativity to portray any scientific conclusion (even those at the rock solid end of the spectrum) as murky. Creationists are evidence of that."

http://theness.com/neurologicablog/index.php/fox-news-the-nfl-and-concussion-denial/