Date of Original Version
Abstract or Description
We study the problem of tracing actual causes, i.e. given an event e, we seek to fully explain why that event happened. This problem was articulated by David Lewis in his work on causal explanations [Lewis, 1986a]. We address the problem by defining the causal history of the explanandum event. Informally, the causal history traces the immediate causes of the explanandum event, the causes of those causes, and so on to produce a full explanation. While related, this problem differs from the problem of determining actual causes where the focus is on identifying individual events that contributed to causing the explanandum event. The central technical contributions of this paper are (a) a formal definition of causal history in the structural equations model; and (b) a theorem that establishes the complexity of the decision problem for causal histories. In addition, we show that our definition cleanly explains a battery of problematic examples from the actual cause literature.