A better way to put this is that the causality, if any, is unclear. However, it's very difficult to construct an ethical study on human participants that is des

A better way to put this is that the causality, if any, is unclear. However, it's very difficult to construct an ethical study on human participants that is designed to show causality. So we're usually left with, at best, a moderately rigorous abductive[1] conclusion. [1] https://en.wikipedia.org/wiki/Abductive_reasoning https://en.wikipedia.org/wiki/Abductive_reasoning