This is the first instalment of a two-part paper on the counterfactual theory of causation. It is well known that this theory is ridden with counterexamples. Specifically, the following four features of the theory suffer from problems: it understands causation as a relation between events; counterfactual dependence is understood using a metric of similarity among possible worlds; it defines a non-discriminatory concept of causation; and it understands causation as transitive. A number of philosophers have recently proposed that causation is contrastive (...) because making contrasts explicit defuses counterexamples. A contrastive causal claim has the following form: C rather than C* causes E rather than E*, where C* and E* are alternative or contrast events. In this paper, I show that making contrasts explicit does indeed defuse some counterexamples. However, I also argue that the examples discussed in the literature all share a common feature, viz. that the original causal judgement is ambiguous in one way or another. Contrasting does not help with counterexamples that do not have this feature. Part II of this paper then takes up the hard cases. (shrink)