 In  Section 2.5  above, we saw that Eells (1991) defines a variety of different ways in which C can be causally relevant for E. C can be a positive, negative, or mixed cause of E depending upon whether C raises, lowers, or leaves unchanged the probability of E in various background conditions \(B_i\). A natural suggestion is that (i) an actual cause of E is a type of positive cause of E; but (ii) for assessing actual causation, only the background condition that actually obtains is relevant. Putting these ideas together, we get: