You are totally correct. This is known as "argument from marginal cases" and the contortions people must enter to get around your argument are frequently hilari

You are totally correct. This is known as "argument from marginal cases" and the contortions people must enter to get around your argument are frequently hilarious. See http://www.nytimes.com/2002/11/10/magazine/an-animal-s-place.html?pagewanted=all http://www.nytimes.com/2002/11/10/magazine/an-animal-s-place...