Levels of linkage: Across-agreement versus within-agreement explanations of consensus formation among states

Decisions in international institutions such as the European Union (EU) are often made by consensus, even when it is not required. Tit-for-tat exchanges provide an explanation for this phenomenon, as such exchanges can help to build up support for agreements states might otherwise not have had an incentive to support. Tit-for-tat exchanges are typically analyzed as trades of support across agreements. However, we argue that the priority of negotiators to further their national and bureaucratic interests makes exchanges across micro-level issues within a single proposal for agreement more prevalent than exchanges across agreements. Using both qualitative and quantitative analyses, we show that such within-agreement, rather than cross-agreement, linkages are related to an increased likelihood of consensus across an array of different EU agreements. To understand consensus in international institutions, more broadly, it is therefore necessary to look at the substantive issues at stake within each agreement.