到目前为止，人类尚未获得“全知全能”的神性。为了适当救济发生了意思表示错误的当事人，我国《民法总则》第147条规定，表意人有权撤销基于“重大误解”实施的法律行为。通过传统的法律解释方法无法明确“重大误解”这一不确定概念的内涵，上述概念必须首先被具体化，然后才能适用于个案。具体化不确定概念的核心方法是案例群的建构，最终目标是形成以类似案例的共同特征为准构成要件的“案例群规则”，获得初步的涵摄能力。我国的重大误解理论，首先应当坚持区别处置“表示错误”和“动机错误”的立场。这是因为，重大误解规则在两种不同错误情形下涉及的原则碰撞、功能定位以及要件需求，均大不相同。在表示错误的场合，错误救济的目的是为意思表示规范性解释的结论提供一个公平性审查和矫正的机制，因此，在构成要件层面，没有必要对表示错误的情形进行进一步的筛选，仅需要明确发动公平性矫正的前提即可。与此不同，在动机错误的场合，错误救济的目的是例外的保障表意人的实质决定自由，因此，错误规则必须首先划定上述例外保护的事案范围，然后明确错误法介入这些情形的前提。两种救济规则，必须分别进行建构。结合司法实践，表示错误原则上只能在满足以下特别要件之一时获得救济：其一，表意人由于错误而承担了显著更重的给付义务，或只能获得显著更少的对待给付，导致合同的给付与对待给付严重失衡；其二，错误导致表意人典型的行为目的无法实现。但是，上述规则在一些场合也存在例外。结合司法实践，参考比较法上的经验，并回溯我国法的内部体系，动机错误原则上只能在满足以下特别要件之一时获得救济：其一，双方当事人对于特定事实存在相同的错误设想，并且双方当事人都基于上述设想而决定以目前的内容订立法律行为。但是，如果一方当事人需要负担事实误认的风险，那么该方当事人无权主张撤销。其二，一方当事人对于特定事实的错误设想因为相对人一方不真实的陈述而产生，并且该不实陈述将导致表意人的行为目的不能实现。但是，表意人对于信赖不实陈述存在过错的，不得撤销。其三，相对人一方违反说明义务，导致表意人产生或维持错误设想，以至于不能实现其行为目的。其四，在法律行为成立之前，相对人基于表意人的告知已明知错误的存在。其五，单方施惠行为中施惠方出现动机错误。

Until now, our human has not yet gained the deity of being omniscient and omnipotent. In order to provide proper remedy for the party in mistake, Art. 147 of the General Part of Chinese Civil Law grants such party a right to avoid the unwanted legal act, if his mistake constituted a “major misunderstanding”.However, traditional methodology of the interpretation of law cannot provide us any further criterions to distinguish between the major or non-major misunderstandings. Such open-ended legal concept must first be concretized before it can be applied. The core method for the said concretization is the construction of case groups. Its ultimate goal is to form a set of “case group rules” which could apply to cases with similar features, so that the open-ended concept would obtain preliminary capacity for subsumption. In the interpretation of the Chinese law of “major misunderstanding”, a clear line should be drawn between “error in expression” and “error in motive”. The necessity of such “dichotomy” emerges from conflicts of the legal principles underlying the two types of mistake and the different purposes of their remedies, which end up in distinct legal requirements. The remedy for error in expression aims to provide an equity review on the normative interpretation of a manifestation of intent, thus the scope of mistake to be examined should not be narrowed, whilst the remedy of error in motive has to pre-determine the range of is protection and establish the prerequisites for cases where the law of mistake should intervene because it is an exceptional mechanism for safeguarding the substantive freedom of self- decision on the part of the mistaken party. The two remedies therefore cannot be combined into one.Based on judicial practice, it is submitted here that errors in expression can only be remedied when, a) so more was paid or so less was asked by the mistaken party because of the mistake, that the equilibrium of the contract was seriously damaged, or b) the typical contractual purpose of the mistaken party was frustrated by the mistake, rendering the transaction valueless for him. However, the up methioned rules should not be apply to cases where, a) no transaction of obligations was made, b) transactional safty was substantially more important, c) a much strict duty to avoid one’s mistake was admitted, and d) the mistaken party’s capacity to understand legal documents was seriously hindered by some special events.Based on judicial practice, referring to the experience of comparative law and traceing back to the internal system of our legislation, it is submitted here that errors in motive are only relevant when, a) both party suffered from the same false assumption, and based their legal act thereupon; however, if according to the intention of the partied, transaction practices, alternative regulations of the law or the principle of fairness, the risk of mistake was assumed by one of the parties, the avoidance of the legal act should be denied for that party, or b) the false assumption as to certain fact of one party was cause by the misrepresentation of the opposite party which rendered his acting purpose unachievable; however, remedy is not allowed, if the mistaken party should not have relied on the misrepresentation, or c) the error in motive was caused or maintained by the opposite party, as a result of that party’s non-performance of his duty to disclosure. In the case of c), the avoidance is only available when the mistake has rendered it impossible for the mistaken party to achieve his purpose of the legal act, otherwise, the mistaken party can only seek for damage basing on the precontractual culpa of the opposite party. Or d) the erroring party had informed the opposite party of the mistake before the juristic act was concluded; or e) the error in motive concerned someone who was granting benefits to the opposite party.