Revisiting the Silent Revolution: Unveiling the Dual Dynamics of Postmaterialism in South Korea via Bounding Analyses of Age–Period–Cohort Effects

This study empirically examines the underlying dynamics of Inglehart’s Silent Revolution in South Korea. Previous research indicates that shifts in postmaterialist values can be explained by three theoretical frameworks—the life cycle hypothesis, the issue-salience hypothesis, and the socialization hypothesis—which respectively correspond to age, period, and cohort (APC) effects. Accurately evaluating the complex mechanisms of this value shift requires decomposing these effects. To overcome the inherent APC identification problem, this study applies bounding analysis, which makes its identifying assumptions explicit and transparent rather than relying on conventional arbitrary statistical constraints. Furthermore, the empirical analysis draws upon a pooled dataset combining the World Values Survey and representative nationwide survey data spanning over three decades (1990–2025). The findings reveal dual dynamics in value change. First, regarding the linear cohort effect, a consistently positive trajectory was identified, supporting the premise of the Silent Revolution that cumulative modernization drives a long-term directional shift. Second, however, this linear trend is complicated by a distinct nonlinear inverted U-shaped cohort effect. The younger generation, facing existential threats, shows a regression toward materialist values related to survival. Consistent with the life cycle hypothesis, materialist tendencies were found to increase with age. These results suggest that while the underlying momentum of the Silent Revolution is firmly active in South Korea, it is significantly refracted by distinct historical experiences and the existential threats faced by specific cohorts.