We can realize that in the context in which the standards to claim truthfully knowledge are so high—e. e., in skeptical context—if we said something like 'I know that I have hands' then this statement would be false. Nevertheless, if we utter the same proposition in an ordinary context—e.g., in a cafe with friends--, where lower standards are in place , the statement would be truth, even more, it's negation would be false. So, only when we participate in philosophical discourses of the skeptical sort, do we seem to lose our knowledge.