This chapter develops the closure thesis—a theoretical framework for understanding the inter-related dynamics of political equality and inequality in the international system based on joining the neo-Weberian concept of social closure and the economic idea of club goods. The closure thesis consists of a constitutive and a causal logic that together contribute an explanation for the reproduction and transformation of political inequalities, understood as the distribution of participatory and procedural rights. The closure thesis makes a constitutive and a causal argument: first, that institutions create rules of closure that over time have narrowed—rather than expanded—the type of political actors considered legitimate participants, thereby constituting members as categorical equals and non-members as categorical unequals; second, that as institutions respond to normative or functional pressures to be include more, and more diverse, states, incumbents face strong incentives to respond by protecting their privileges through institutional designs—such as assimilative multilateralism, hierarchical multilateralism, and exclusive multilateralism—that distribute procedural rights unequally. The closure thesis thus contests the view that the globalization of the international system has been a process of greater inclusiveness of formerly marginalized actors accompanied by a more egalitarian and even democratic multilateral institutional order.

The international relations (IR) literature appears to be divided into two fundamentally different views about the basic structure of the international system and its institutions. On one view, the expansion and opening of international institutions in the 20th Century to include more actors and greater geographical reach, combined with strengthening democracy norms, are driving the democratization of international institutions. At the same time, a more critical literature is emerging that instead views the system as permeated by multiple forms of hierarchy and deep structures of domination. This chapter, in contrast, argues that political equality and inequality obstinately co-exist in international institutions because of their very role in regulating access to collective goods. It develops what I call the closure thesis to explain how institutional designs reflect an ongoing struggle between the assertion of equal rights and the preservation of unequal privileges. This argument requires re-thinking three premises: that equality and inequality are antagonistic; that greater inclusiveness typically promotes a move towards greater equality; and that international institutions provide global public goods. This chapter elaborates on these points, situates them in the literature, introduces the closure thesis, and outlines the rest of the book.