Prevention, Preemption, and the Principle of Sufficient Reason

[Introduction] One event, e, counterfactually depends upon another event, c, just in case e would not have occurred had c not occurred. Beginning with the seminal paper of David Lewis in 1973, there has been a lively philosophical tradition of trying to analyze token causation in terms of counterfactual dependence. The simplest possible counterfactual theory of token causation—henceforth the simple theory—would identify token causation with counterfactual dependence: c is a token cause of e just in case e counterfactually depends upon c. This simple account is threatened by counterexamples on both sides. Some authors, but by no means all, take cases of prevention and omission to show that there can be counterfactual dependence without token causation. Cases of preemption have been widely taken to show that there can be token causation without counterfactual dependence; many authors (but not Lewis himself) also consider cases of overdetermination to be counterexamples to the necessity of counterfactual dependence for token causation. There have been many attempts to deal with the problems of preemption and overdetermination, none entirely satisfactory. We will examine the shortcomings of some of these theories in sections 11–13.