“Who Islamises us?”: Does political ideology moderate the effects of exposure to different Great Replacement Conspiracy explanations on radical collective action against different targets?

Conspiracy theories against outgroups (e.g., the Great Replacement Conspiracy [GRC]) are believed to fuel radicalisation. Two experimental studies with British and American samples (N_total = 1690) examined how different GRC narratives and political ideologies influence radical collective action against Muslims and ideologically opposed political elites. We predicted that the Muslim conspirator and left-wing conspirator (vs. control) narratives would increase radical action intentions against Muslims among right-wingers (Hypothesis 1). We also predicted that the left-wing conspirator narrative (vs. other conditions) would increase radical action intentions against left-wing elites among right-wingers (Hypothesis 2a), and the Muslim conspirator narrative (vs. control) would do the same (Hypothesis 2b). Furthermore, we predicted stronger radical intentions towards right-wing elites among left-wingers when exposed to the left-wing conspirator condition (Hypothesis 3). Despite limited support for these hypotheses, both studies showed that exposure to any GRC narrative increased radical intentions against Muslims, suggesting that the conspirator group does not play a strong role in anti-Muslim radicalisation. The lack of statistically significant effects on other targets may be due to conservative hypothesis testing. Theoretical and societal implications are discussed, providing critical conceptual and methodological avenues for future research on conspiracy theories and radicalisation.