Lyric discussion by Moulingalette 

Cover art for Know lyrics by System of a Down

I think that one of the basic meanings of this song is that you should "never think you know why, know." Unless you have experience with something and have seen or done it for yourself, don't presume that you know about it, and even then, you should never think that you are for sure right. In reality, we can not be sure of anything, so we should never think we know why.