From the thesis: "This thesis investigates how psychological responses to uncertainty contribute to ideological extremism in the U.S. It draws on a pair of theories from social psychology. The first is Need for Cognitive Closure (NFCC), which refers to a desire for definitive answers and an intolerance for ambiguity; the second is Uncertainty-Identity Theory (UIT), which posits that individuals reduce self-conceptual uncertainty through group identification: this study then specifically explores how cognitive and social motivations converge in extremist settings. NFCC drives a preference for order, uniformity, and authoritarian leadership, fostering ideological rigidity. UIT complements this by explaining how high-entitativity groups offer stability, clearly defined roles, and identity clarity. Using McCauley and Moskalenko's two-pyramids model, this thesis distinguishes extreme opinion from extreme action and demonstrates how NFCC and UIT illuminate the psychological mechanisms underlying both. Findings suggest that extremism often fulfills epistemic and identity needs rather than being purely ideological. Together, these frameworks offer a multidimensional explanation for how individuals become attracted to extremist groups, especially in contexts of social, political, or personal uncertainty."