 Eells’s taxonomy brings out an important distinction. It is one thing to ask whether C is causally relevant to E in some way; it is another to ask in which way C is causally relevant to E. To say that C causes E is then potentially ambiguous: it might mean that C is causally relevant to E; or it might mean that C is a positive cause of E. Probabilistic theories of causation can be used to answer both types of question.