利益与成本是指导国家遵守国际法的重要依据。在该机制下,有两大国际法遵守的动力:一为国际社会之舆论;二为其他国家的对等报复。其中,在国家之间形成重复博弈的情况下,社会舆论对国家遵守国际法记录将国家在国际交往中的未来利益贴现至当下,形成国际法遵守的动力。同时,其他国家的报复可以通过增加违法国的行动成本而促使其放弃违法行为。社会舆论和报复发挥其推动国际法遵守的作用各有条件,也各有局限。其条件的本质在于如何增加遵守国际法之利益或者增加违反国际法的成本以促使理性之国家步入守法之轨道;其局限性的本质在于利益与成本并非国际法遵守的唯一动力。当然,仅依利益与成本无法全面解释国际法遵守的问题。 Interests and costs are important basis for guiding the country in complying with international law. Under this mechanism, there are two main motivations for international law to observe: one is public opinion in the international community and two are equal reprisals in other countries. Among them, when repeated games are formed between countries, public opinion discards the country’s future interests in international exchanges by discounting the country’s compliance with international law records and forms the driving force for the compliance with international law. At the same time, retaliation by other countries can prompt them to renounce violations by increasing their costs of action. The role played by public opinion and retaliation in promoting their compliance with international law has its own conditions and limitations. The essence of the conditions lies in how to increase the compliance with the interests of international law or increase the costs of violating international law in order to push a rational country onto the path of keeping the law-abiding. The essence of its limitation lies in that interest and cost are not the only motives for compliance with international law. Of course, the issue of compliance with international law can not be fully explained by interest and cost alone.