A risk factor is something else and more abstract than a cause. In medicine, there is a lot of talk about risk factors, but not so much about causes: Why does a person develop cancer, for example? This question is almost unheard of in medicine. To try to answer the considered a form of hubris, it is provocative. As a rule, it is claimed that cancer strikes randomly. That is, when risk factors have been taken into account. Among twenty heavy smokers, for example. . .