 Whereas knowledge of what speakers implicate is essential to fully understand speakers, knowledge of what sentences implicate is a critical component of our knowledge of a language. This is obvious for sentences with semantic implicatures like  (3a).  But speakers are not fully competent with “some” unless they know that it is related to “all” in a way it is not related to “several” or “two”. A man using  (5a)  may mislead others if he does not realize that it implicates  [5b],  and fail to communicate if he thinks it implicates “It is not the case that several athletes smoke”.