This thesis tests an agent-centric, social constructivist perspective on interstate socialization. I draw upon diplomacy at the United Nations—especially, at the General Assembly—as the focal point for that socialization in a global, multilateral context. My research question concerns how states can initiate a socialization process that cumulatively builds a consensus on an issue over time. My argument is that a “core” coalition of states can create a spotlight of diplomatic pressure that draws into focus an issue. That diplomatic pressure sets in motion a process of collective legitimization, which assumes a life of its own and creates common expectations that make support for a particular position “legitimate”. Over time, these expectations can incline other states—in particular, those opposing or otherwise “on the fence”—towards joining in on a common position, leading to a convergence in expectations in relation to the issue. What results is interstate socialization that takes place in the sense that public—though not necessarily private—viewpoints converge around a common, more legitimate or socially sustainable stance on the issue. The outcome reflects a social compromise in which socialization subjects eschew public association with the “illegitimate” or socially unsustainable position. Socialization subjects do not necessarily take to heart and change their own private views.

To evaluate this theoretical argument, my thesis considers three issue areas as case studies: racial discrimination in South Africa from 1946 to 1961, the United States’ embargo on Cuba from 1991 to 2016, and the ban on nuclear weapons from 1946 to 1961. The former two case studies demonstrate empirical support for my theoretical argument, provided the contribution of certain empirical factors specific to the case studies. These two case study chapters advance my theoretical argument in reference to specific examples of states that were moved by the core coalitions’ diplomatic efforts. The latter case study considers the ban on nuclear weapons as an issue area where socialization does not occur. The point in studying an nonpositive case study is to add nuance to my theoretical argument and empirical tests by considering the conditions under which socialization will and will not occur. I posit that an agent’s perceived integrity on an issue can make socialization efforts more or less influential. Specifically, socialization efforts are more likely to fail when proponents lack that integrity—and are therefore seen to be hypocritical—because the target states do not see a political downside to maintaining the status quo. By integrity, I mean a social constructivist (and not a rationalist) take on “reputation”, which relates to the extent to which a potential socialization subject regards a socialization agent as a trustworthy advocate of a cause.