The limits of information revelation in multilateral negotiations: A theory of treatymaking

States negotiate over the specific terms of multilateral treaties because those terms determine states’ willingness to ratify the treaty. In some cases, a state might decline to ratify a treaty it otherwise supports because specific terms are too far from those it prefers. States and inter-governmental organizations negotiating treaties would like to uncover the minimal terms needed to secure the ratification of key states, but under what circumstances will those states candidly reveal those terms? Using a spatial representation of the issues in a treaty negotiation, we use mechanism design to determine what information states will reveal in a treaty negotiation. We find that states are willing to reveal how they would like tradeoffs between different issues to be resolved but not the minimal terms they require for ratification. Further, negotiations cannot always separate types that need concessions to ratify from other types that would like concessions but would ratify the treaty even if they do not receive them. These findings provide insight into how treaty negotiations can succeed or fail, and they lay the theoretical groundwork for a new line of empirical research on how multilateral treaties are negotiated.