Replication Data for: The Dynamics of Enlargement in International Organizations

Most international organizations (IOs) expand their membership over the course of their lifespan. Although these enlargements tend to be heralded as normatively positive — for the IOs themselves, for the new members, and for cooperative outcomes more generally — expansions can also lead to conflicts in the organization. What conditions lead to enlargement rounds that reshape an organization in unexpected ways? We argue that, depending upon the diversity of the initial group of countries, members may vote to admit new entrants that can tilt organizational decision-making in unexpected directions. We anticipate fewer enlargements with lesser impact on the character of the organization among organizations that have either a smaller range of founding members or a relatively even initial dispersion. We develop an agent-based model that accounts for the complex decision-making environment and social dynamics that typify IO accession processes. The model helps us explain how the nature of decision-making in organizations can shift following enlargement, likely changing the organization’s output and goals.

绝大多数国际组织（International Organizations, IOs）在其存续周期内都会逐步扩大会员规模。尽管这类扩员行动往往被冠以规范层面的积极意义——无论是对国际组织自身、新成员国，还是更广泛的合作成果而言——但扩员也可能引发组织内部的冲突。究竟是何种条件，会使得一轮轮扩员以出乎预料的方式重塑国际组织的形态？我们提出，鉴于初始成员国群体的异质性程度，成员国或会投票接纳新成员，而这类新成员可能会以出乎预料的方向使组织的决策走向发生偏移。我们预判，若国际组织的创始成员国范围较小，或是初始成员国的分布相对均衡，则其扩员频次会更低，且扩员对组织特质的影响也更为有限。我们构建了一个基于智能体的模型（Agent-based Model），用以刻画国际组织入盟进程中典型的复杂决策环境与社会互动动态。该模型能够帮助我们阐释，国际组织的决策本质会如何在扩员后发生转变，并进而可能改变组织的产出成果与既定目标。