It's still interesting to note that we assume "nothing to do with each other" with some cases, "obscured" relationships on other like the OP's second point. Wh

It's still interesting to note that we assume "nothing to do with each other" with some cases, "obscured" relationships on other like the OP's second point. Where it falls relies on the viewer's knowledge of the problem space, which can also be limited enough to lure them into false causations. My point would be that a single graph showing two trends without any further info should never be taken as more information than "there is two trends". You'll still be free to decide there is true causality based on other information you believe.