As a metaphor, you can imagine a blind person in the wilderness who has no idea what is in front of him. He will proceed cautiously, perhaps probing the ground with a stick or his foot. You could also imagine a delusional man in the same wilderness incorrectly believing he's in the middle of a foot race. The delusional man just run forward at full speed. If the pair are in front of a cliff...

As the saying goes, it's not what you don't know that gets you into trouble. It's what you know for sure that just ain't so.