摘要： 原因力的确定与比较，对于侵权行为的归责、确定责任范围及分配责任都颇具影响，而在复合因果关系形态下，其对确定责任范围及分配责任的意义更为彰显。有别于以往研究的是，本文试图从各种因果关系学说中梳理出原因力理论，厘清原因力的概念、性质，并在区分事实原因力与法律原因力的前提下探讨其作用。对于复合因果关系形态的侵权行为，应坚持过错比较为主、法律原因力比较为辅的综合说来确定责任范围及分配责任。

关键词: 因果关系 , 事实原因力 , 法律原因力 , 过错

Abstract: It is significant to determine and distinguish causative potency while affirming，confining and apportioning tortfeasors’liability，especially in multiple causation．Based on various doctrines of causation，this thesis attempts to define causative potency and then compares factual causative potency with legal causative potency in order to analyze the function of causative potency．The principle，of which liability is in proportion to the degree of fault as well as legal causative potency，should be applied to torts of multiple causation so as to determine the scope of liability and apportion liability．

Key words: causation, factual causative potency, legal causative potency, fault