This dissertation interrogates the phenomenon of disaffection in post-World War II democracies and, in doing so, offers a theory of the affective dimension of democratic politics. Although many countries have formally democratized after World War II, they suffer from political apathy, withdrawal, and disillusionment-in short, disaffection. Why have democratic institutions failed to inspire popular support necessary to sustain democratic forms of life? A dominant strand of democratic theory represented by Rawls and Habermas is not well-equipped to address this vital question, insofar as it fails to consider how affect works with reason, not as a subsidiary but an equally constitutive force, in establishing and realizing norms of democratic politics. This is theoretically blinding since a unique frame of democracy that became dominant in the postwar era (which I call "instrumental democracy") has systemic tendencies to produce democratic disaffection. Instrumental democracy reduces democracy to an instrument that merely legitimizes, rather than contests or renegotiates, political goals predetermined by elites and technocrats. I trace the origins of instrumental democracy to the Cold War when anti-totalitarianism, market capitalism, and a highly insulted technocracy concomitantly emerged to the effect of dissolving the collective, public dimension of democracy. I scrutinize the logics of instrumental democracy by analyzing behavioralism and rational choice theory as symptomatic articulations of Cold War imperatives, and investigate its evolution in the late twentieth century by examining democratization in Chile and South Korea. Bringing my empirical analysis into theoretical focus, I reinterpret Hannah Arendt's political theory through the prism of her creative, if underdeveloped, appropriation of two supposedly incompatible themes: Heidegger's concern with affect and Marx's critique of alienation. Thus interpreted, Arendt's theory helps us recognize that people's affective disposition toward democracy is closely connected to the structure and distribution of power. By engaging in a mutually constitutive dialogue between theory and history, I aim to identify and challenge one of the most formidable yet underappreciated trends of our time that threatens to impoverish our understanding and practice of democracy.