摘要： 《合同法》第84条规定了债务人和承担人缔结的债务承担合同，它在交易习惯和逻辑结构上都与债权人直接参与的承担方式有所区别。对于第84条的基础理论，必须整合无权处分和第三人利益合同等不同的制度进行建构。在此基础上，对第84条运作中涉及的各个要素，包括债务承担合同、债权人同意、承担的原因、承担人的抗辩权、担保的存续等问题进行阐释，以保障良好的法律适用。

关键词: 债务承担, 履行承担, 债权人同意, 无权处分, 第三人利益合同

Abstract: Article 84 of the Contract Law provides for the contract of assumption of debts concluded between the debtor and the assumer, which is different from the way in which the creditors are directly involved from the aspect of logical structure and trading habits. For the foundation of doctrine of Article 84, it is necessary to integrate the different systems including unauthorized disposition and contract in favor of the third party. On this basis, the various factors involved in the operation of Article 84 could be researched profoundly, including the agreement of assumption of debts, the creditor's consent, the cause of assumption, the rights to defense of the assumer, the continuation of the guarantee, and so on to make the application of law precise.

Key words: Assumption of Debts, Delegation of Payment, Unauthorized Disposition, Contract in Favor of the Third Party