Philosophers have been interested in the nature of causation for as long as there has been philosophy. They have been interested in what we say about the world when we say that one thing caused another, and in whether there is anything in the world that answers to the causal claims we make about it. Despite the attention, there is still very little agreement on the most central question concerning causation: what is it? Is it a matter of the instantiation of regularities or laws, or counterfactual dependence, or manipulability, or transfer of energy, for example? One reason for the lack of a consensus view is the sheer difficulty of the task; anyone familiar with the causation debate as it has been conducted in recent years will be familiar with a vast range of theories and counterexamples, which collectively can lead one to suspect that no univocal analysis of the concept of causation is possible.