In most instances, to establish causality we use indirect evidence ... note sometimes there's a threshold effect when it comes to causation. That is, an exposure doesn't cause disease until ...

University of California Press. Marini, M.M., and B. Singer (1988). "Causality in the Social Sciences." Pp. 347-409 in Sociological Methodology 1988. "Correlation cannot prove causation." ...

If any causal explanation is correct ... but it demonstrates how scientists approach establishing causation for a phenomenon, especially one predicated on the observation of initial correlations.