Under the but-for requirement of causation, a tort injurer cannot be held liable for more than the difference between the loss the victim would have suffered if the injurer had not been negligent, and the loss that is in reality suffered. We ask whether this causation requirement yields efficient precaution in the context of two or more injurers. Contrary to a widely accepted view, we find that but-for causation may lead to the existence of an inefficient Nash-equilibrium. We characterize when this may occur and compare those instances with precedent in which courts have not required but-for causation. Moreover, we ask whether alternative concepts of causation do better than but-for causation in terms of incentives. We find that while both the NESS-test and the Shapley provide optimal incentives when injurers act simultaneously, there are reasons for considering the Shapley-value as the more satisfactory concept of causation.

在没有因果关系的要求下，侵权加害人的责任不能超过在加害人没有过失的情况下受害人可能遭受的损失与实际遭受的损失之间的差额。我们询问这种因果关系要求是否会在两个或更多伤害者的情况下产生有效的预防措施。与广泛接受的观点相反，我们发现除非因果关系可能导致低效纳什均衡的存在。我们描述了这种情况何时可能发生，并将这些情况与法院没有要求但因果关系的先例进行比较。此外，我们询问在激励方面，因果关系的替代概念是否比因果关系更好。我们发现，虽然 NESS-test 和 Shapley 都在伤害者同时行动时提供了最佳激励，