Hypothetical causation does not work on causation but on damage: to limit the scope of damages according to hypothetical course. Whether hypothetical causes can work on the calculation and determination of damages caused by former injurious act or not depends on the time-standard of damage calculating, nature of hypothetical cause and whether the damage is direct or not. The first issue determines the time scope of hypothetical causes which can amend damages. The second issue excludes such hypothetical causes which can be attributable to a third person. Whether damage is direct or not determines the scope and degree of amendment on damages by hypothetical causes.The theoretical foundation of the amendment on damages by hypothetical causes lies on the idea of the damage and the risk distribution mechanism. The idea of damage concerns to the definition of damage, and determines the quality and quantity of certain elements which will affect the evaluation and calculation of damages. The risk distribution mechanism determines whether the burden of the risk should be taken by the victim or the others. It approves to the practice of many countries in making distinction according to different natures of hypothetical causes. As to the relationship between hypothetical causation and compensation for damage, our country has no sufficient discussion and unified standpoint both in theory and practice. In legislation, the time-standard of damage calculating is set to the time when the damage happens, which limits the amendment effect of hypothetical causation theory. Therefore, we should define the intension and extension of the damage properly. It is suggested that the time calculating damages be taken as fundamental normal formulas. It is also suggested to distinguish the hypothetical causes of the act of a third party from others. If the damage could have been caused by a third party, such hypothetical cause does not affect the scope of the damages caused by the former injurious act. When the damage could have been caused by the other later causes, the liability of the preceding injuring person should be limited accordingly. Ultimately, the theory of hypothetical causation should be in general applied to indirect damage, but not to direct damage. |