当今时代，信息技术呈现出迅猛的发展之势，诸多不确定因素的介入，危险行为与危险物品数量的不断增多，使得行为和损害结果之间因果关系的认定问题变得愈发复杂和困难，因果关系不确定的侵权现象越发普遍。在这类案件中，虽然已经证实被告的确存在过错，而且其侵权行为也很可能是造成原告损害的原因，但传统“全有或全无”因果关系原则的适用，会导致被告免于承担损害赔偿责任而原告难以获得相应救济的窘境。基于此，我国立法上，通常会采取以下几种方式来加以处理：推定因果关系、适用连带责任，或推定平均责任。然而，在某些案件中，这样又会造成对侵权人过度震慑，亦或是对受害人的保护不周等后果。对此，我国可以借鉴域外已广泛探讨和实践的比例责任规则（the rule of proportional liability）。这一规则以比例因果关系为适用前提，主要源于对英美法的司法实践中，在因果关系不确定侵权中适用传统因果关系理论的做法以及对侵权损害赔偿中占支配地位的“完全赔偿原则”，亦即“全赔或不赔”（all or nothing rule）传统规则不满的情形下被提出的。比例责任规则是根据被告行为造成原告损害的概率或可能性要求被告对原告之损害承担相应损害赔偿责任的规则。 比例责任规则的适用，对解决因果关系不确定侵权中因果关系的认定以及不同当事人之间的责任分配问题都起着重要作用。其价值主要体现在两点：第一，它符合实现侵权法两大价值目标的要求，即矫正正义（填补损害）与适度威慑之功效。第二，它妥善地处理了在因果关系难以确定的情形下，因果关系的判定和不同主体责任分担的问题，其适用更能满足侵权法“公平地分配人类损害的费用和风险”的基本目的。故此，为了更好地处理我国因果关系不确定侵权中因果关系如何认定以及侵权责任如何分担之难题，我国侵权法上应当确立比例责任规则，将其作为数人侵权责任分担形态的特殊规则加以补充适用。 除绪论与结语外，正文的主体结构分为六章。绪论部分介绍了本文研究的意义，梳理了国内外研究现状，并就本文的框架、研究方法与创新点予以说明。结语部分概括和总结本文的主要观点和建议，是笔者观点的总结性体现。 第一章试图以侵权法上因果关系理论的发展为主线，通过对传统因果关系理论的分析探讨，揭示了因果关系既有认定理论在解决因果关系不确定侵权中因果关系认定与责任分担问题时所带来的弊端，进一步引出一种新型的因果关系的认定理论与侵权责任的分担方式，即比例因果关系与以其为适用前提的比例责任规则。本章主要内容包括因果关系在归责中的作用与认定理论之评析、比例因果关系的内涵，比例责任规则的产生、界定、特征与价值。 第二章是关于比例责任规则的比较法考察。该部分以比较分析的方法，通过对欧洲侵权法，美国侵权法以及我国侵权法关于比例责任规则相关问题的理论研究、实践运用和立法等方面的分析探讨，揭示比例责任规则适用范围的特殊性、规则体系的独立性以及域外法经验对我国的一些启示。 第三章探讨市场份额规则向比例责任规则的扩展适用问题。市场份额规则被称作是比例责任规则这一更广泛概念的一个变量，其产生、适用、不同模式及其扩展适用对比例责任规则理论体系有着重要意义。本章主要论述市场份额规则为大规模产品侵权中因果关系的认定提供了一种新的思路，然而其仅适用在具有‘可替代性’特征的产品侵权案件中。比例责任规则突破了‘可替代性’特征的限制。相较于市场份额规则适用的局限性，比例责任规则的适用范围更广泛，很多因果关系不确定的侵权均可采纳比例责任规则作为解决责任分担难题的手段。 第四章主要研究存活机会丧失侵权中比例责任规则的适用问题。通过对存活机会丧失侵权相关问题的探讨，重点论述比例责任规则在此类侵权中适用的合理性与正当性。本章主要内容包括：存活机会丧失侵权之损害赔偿、比例责任规则在这类侵权中的适用考察以及我国这类侵权中比例责任规则适用的现实思考。 第五章探讨其他类型侵权中比例责任规则的适用可能性问题。本章以多因不明的大规模网络侵权和高空抛物致害侵权为考察对象，分析探讨比例责任规则在这两类侵权中适用的可行性方案。 第六章试图就构建我国侵权法上比例责任规则的法律制度问题进行探讨。本章认为：应在我国侵权责任分担体系内确立这一规则，将其作为数人侵权责任分担形态的特殊规则以破解因果关系不确定侵权中的因果关系认定与责任分担的问题。本章主要内容包括：比例责任规则的立法必要性、可行性，立法定位以及比例责任规则在不同类型因果关系不确定侵权案件中适用的具体建议。

In today's era, information technology is developing rapidly, intervention of uncertain factors, and the surge of dangerous acts as well as articles, all these make it more difficult to identify the causation between the conduct and consequences of harm, there is an increasing phenomenon that tort whose causation is uncertain prevails in modern society Regarding such torts, in some cases, the applicability of conventional “all-or-nothing” rule exempts defendants from their responsibilities for torts and thus makes it impossible for plaintiffs to obtain relief, even if the defendants are proven to have infringed upon the plaintiffs’ rights and their torts might be causes of the plaintiffs’ damages. Regarding such problem, the legislation of our country often considers “presumption of causality, joint and several liabilities, presumption of average responsibility” etc. to solve the problem while in some situations such a legislation will lead to the effect that the infringed are under compensated while the tortfeasor are over detered. Considering that, in the author’s opinion, we can learn from foreign countries about proportional liability which is based on the theory of proportional causation and has been widely discussed and practiced for a long time. The proportional liability rule originated from judicial practices of English and American laws, where traditional theories on causations apply to torts with uncertain causations. It is brought forth under the circumstance that the dominant “all or nothing rule” is unsatisfactory in identifying compensations for torts. Proportional liability rule, that is apportion of liability based on the proportion of probability that the infringement is an essential element of consequences of harm. The Proportional liability rule plays a significant role in the identification of causation and the distribution of liability between different parties in the situations that the causation is not certain, the use of proportional liability could contribute to the advances in the two major policies of appropriate deterrence and corrective justice. Its value mainly includes following aspects: Firstly, the use of proportional liability could contribute to the advances in the two major value-related goals of tort law: corrective justice and appropriate deterrence. Secondly, it better resolves the problems of the identification of causation and the distribution of liability between different parties in the situations that the causation is not certain. The proportional liability rule is more helpful for realizing the essential purpose of tort law, which is “equally allocating expenses and risks of human damages. Therefore, in order to better solve the problems of the identification of causation and the distribution of liability between different parties in the situations that the causation is not certain in our country, the proportional liability rule should become one part of Chinese tort law. It could be established as a general rule for identifying several persons’ tort liability and used as a supplemental rule. Except for introduction and conclusion, this paper consists of six chapters. The introduction part introduces the significance of this paper, presents the research status at home and abroad, and illustrates its structure, research methodology and theoretical innovation. The conclusion part concludes the main ideas and suggestions; it is the embodiment of the author’s own viewpoints. Chapter 1 attempts to take the development of the causality theory in the Tort Law as the main line, through the analysis and discussion of the traditional causality theory, reveals the disadvantages brought by the causal relationship existing identification on theory in solving the problem of causal relationship identification and liability sharing in tort with uncertain causal relationship, and further leads to a new theory of causal relationship identification and the way of tort liability sharing, namely, proportional causality and proportional liability rule based on it. This chapter mainly introduces role of causation in liability imputation, the review of theories on causation, and connotation of proportional causations, as well as the historical logic, definition, features and value of the proportional liability rule. Chapter 2 examines extra-territorial laws of the proportional liability rule. In this part, European, American and Chinese tort laws are comparatively studied from the perspective of their major content with respect to theoretical research, practices and legislations to summarize the particularity of the scope of application, the independence of rule system of the proportional liability rule and some enlightenments of extraterritorial law for China. Chapter 3 introduces the proportional liability rule about extension of market share liability. Market share liability is reckoned as a variable of the proportional liability rule in a broader sense. Its emergence, applicability, extension is of great significance for the theoretical system of the proportional liability rule. It mainly discusses that market share liability rule provides a new way of thinking for large determination of causality in the infringement of scale products, but it only applies to product infringement cases with "substitutability" characteristics. The proportional liability rule breaks through the limitation of the characteristic of substitutability. Compared with limitations upon applicability of the market share liability, the proportional liability rule is more applicable. Many torts with uncertain causation can adopt the proportional liability rule as a mean to solve the problem of liability sharing. Chapter 4 describes the applicability of the proportional liability rule to torts with a loss of chance for survival. It focuses on the rationality and legitimacy of the application of the proportional liability rule in this kind tort through the discussion of the problems related to torts with a loss of chance for survival. The main contents are as followed: the damage compensation under the tort with loss of chance for survival, and the application of the proportional liability rule in this kind of infringement and realistic thinking of the application of the proportional liability rule in this kind of tort in our country. Chapter 5 examines the possibility of applying the proportional liability rule in two types of tort: large-scale network torts with unknown multi-cause and the high altitude parabolic damage liability. Chapter 6 attempts to discuss the legal system of establishing the proportional liability rule in China's Tort Law. This chapter holds that this rule should be established in the system of tort liability sharing in China，use it as a special rule of the liability sharing pattern of multi-person infringement to solve the problem of causality determination and liability sharing in the infringement of causality.