In November 2013, Ukraine's government, under pressure from neighboring Russia, reversed plans to establish closer trade ties with the European Union (EU). As Erik Voeten's important book, Ideology and International Institutions, explains, the nature of the choice facing Ukrainians in late 2013 went well beyond cost-benefit calculations over the relative superiority of a commercial partnership with the EU or with Russia. At its core, the decision concerned ideological alignment. By agreeing to terms with Western Europe, Ukraine signaled fealty to the bundle of “liberal” principles sedimented in the EU and in other like-minded institutions (International Monetary Fund, World Trade Organization, NATO, etc.). The ideological stakes in the Ukrainian example illustrate a more general feature of multilateralism in world politics, Voeten argues that “multilateral politics can often be understood as an attempt to move the policy status quo in a particular direction in a low-dimensional ideological space” (p. 174). Put simply, when countries make choices about multilateral institutions—whether to join, to withdraw, to engage, to ignore, or to create new ones—their choices are partly shaped by their ideological positions.

Ideology is conceptualized broadly in the book as “a widely understood set of interconnected