People too often tolerate uncertainty prior to taking action; worse, some people believe that omniscience or infallibility are prerequisites for being certain, so they conclude that certainty (and therefore knowledge) is never possible. To any person who proclaims that "you can never be certain of anything", ask them: "are you sure?" and watch what happens.
Mike Klepper
certainty, infallibility, knowledge, omniscience, self-contradiction, uncertainty