In this article we analysis the position of rationality in the JCPOA discourse as one of the most important decisions of the moderators in Iran’s foreign policy. What is known as rationality in foreign policy can be defined in various versions, in the current paper we take what is theorized by John Rawls and can be summarized more or less as “optimizing the cost-benefit” to analysis the discourse of rationality in foreign policy of the moderate forces, especially in JCPOA issue from which we try to investigate the basis of their macro foreign policies.

Although the local reflection of this rationality and basing in on cost-benefit calculation in politics may be something close to expediency, but from a more comprehensive perspective it will be possible to find a theoretical unity between these two. This unity between the cost-benefit calculation and expediency is what can be some sort of summation between the actual politics and the governing ideology in the Islamic Republic political system as a conceptual determiner. The main claim of the moderated tendency is that with keeping the identities of the political system and reforming in some cognitive parts and executive dimensions of the foreign policy it is possible to optimize the cost/benefit balance and follow the national interests.