.... Correlations are an essential component for any case of causality. If you don't have at least one correlation as part of your case for causality, then you likely do not have a case for causality. Causality of some sort generally explains a correlation (unless it can be plausibly explained as purely random), and the difficulty is determining the direction of causality. If X correlates with Y, then maybe X causes Y, but maybe instead Y causes X, or maybe instead a third variable Z causes both X and Y. ...