General Claims & Their Contradictories

In Chapter 8 I read about a lot of interesting concepts but one that was most interesting to me was the section about General Claims and Their Contradictories.  Epstein starts off talking about how we need to know how to reason using general claims that assert something in a general way.  This relates to real life situations because we are always using claims in our conversations.  An example of a general claim would be "Dedicated football players practice hard everyday. John practices hard everyday. So John is a dedicated football player." This would be an example of a general claim that we may use often.  Even though this may sound like a valid claim, it is not.  It doesn't say "All" dedicated football players, so therefore John may not practice hard everyday.  To make this more clear Epstien talks about how "All" means every single one. "Some" means At least one, and  "No means not even one."