A reasonable working definition of causality, used by almost all scientists today, is that X causes Y if a change in X, unaccompanied by any other change, chang

A reasonable working definition of causality, used by almost all scientists today, is that X causes Y if a change in X, unaccompanied by any other change, changes Y. At root, this is indeed a statement about correlations, but it's a special kind of correlation, which is hard to estimate from observational data where many other things may change along with X.