I really don't like that phrase. Evidence doesn't speak for itself. Evidence requires interpretation. I spent this past semester doing ethnography. Towards the beginning we were asked to remove ourselves from the situation, so to speak, and be a completely objective observer. We should assume we know nothing about the situation. That we are a complete outsider and simply describe what we see. We were asked to do this so we could see the complete ridiculous nature of that assumption, that we can take ourselves out of the picture. Part of human existence is interpretation, and we can not live without it. Simply the manner in which evidence is presented is involved in interpretation. What do you show people? Simply choosing what is relevant information and what isn't relevant is interpreting it. Deciding what angle to look at something as opposed to another angle is interpreting it. I understand that its an idiom and they almost never mean what the sentence blatantly seems to. When someone says, "the evidence speaks for itself" they mean that the conclusion they have drawn from interpreting the evidence is what they think everyone will interpret it as. Sometimes people are right, most times they're wrong. Evidence without interpretation is meaningless. Evidence without meaning is purposeless. I wouldn't want to live life without purpose, so I choose to not "let the evidence speak for itself."
For His Glorious Name,