Populism as a Threat to Liberal Democracy: Evidence from Europe

Over the past two decades, populism has emerged as a significant political phenomenon across Europe and many parts of the globe. With a growing number of populists elected to government, it is widely accepted that populism has negative effects on liberal democracy. However, there have been few empirical studies–and virtually no causal ones–that test how and if this is true. In this paper, I unpack the different ways populism may affect the level of democracy in a country. Specifically, I analyze how government status and host-ideology of the populist party may moderate the relation- ship between populism and level of liberal democracy. I use the Varieties of Democracy (V-Dem), PopuList, and ParlGov datasets to conduct a Difference-in-Differences (DiD) design across 30 European countries over 23 years (2000-2022). The results suggest that liberal democracy scores decrease in the years following populist entry into government, when compared to elections in which populists do not enter government. Critically, these results only hold for right-wing populists. Among left-wing populists, I find no evidence of democratic deterioration. The findings overall show that both government status and host-ideology are key factors that determine how populism affects liberal democracy.