I have always liked the saying that "Science is defined more by its questions and less by its answers." I have come to realize that that almost plays into the ID "Teach the Debate" argument. What is necessary is a way to determine what is a scientific question.
Skeptico, via the Skeptics Circle, answers the appeal to “science doesn’t know everything” with a call for evidence. A question needs a basis in what is already known. Much like you need to know the starting point of a journey to make decent directions, you need to start with knowledge so that any new discovery is of a piece with the rest of science. I don't see how that is so difficult.