 So far we have considered how the counterfactual theory of causation works under the assumption of determinism. But what about causation when determinism fails? Lewis (1986c) argues that chancy causation is a conceptual possibility that must be accommodated by a theory of causation. Indeed, contemporary physics tells us the actual world abounds with probabilistic processes that are causal in character. To take a familiar example (Lewis 1986c): suppose that you mischievously hook up a bomb to a radioactive source and Geiger counter in such a way that the bomb explodes if the counter registers a certain number of clicks within ten minutes. If it happens that the counter registers the required number of clicks and the bomb explodes, your act caused the explosion, even though there is no deterministic connection between them: consistent with the actual past and the laws, the Geiger counter might not have registered sufficiently many clicks.