["Political Psychology, EarlyView. ", "\nAbstract\nThis study proposes a novel, certainty‐weighted account of the process by which political beliefs shape political attitudes. Building upon expectancy‐value frameworks, this paper introduces belief certainty as a moderator of belief impact. A Bayesian partial‐pooling approach is used to test a model positing how beliefs about what the Patient Protection and Affordable Care Act does and does not do relate to overall attitudes toward the law. This analytic method manages the complexity of multiple potentially correlated beliefs and evaluations by imposing a structural constraint to avoid multicollinearity and enable accurate estimation of parameters. Data from a nationally representative sample survey of American adults support the model's core propositions. Counterfactual simulations further reveal that belief certainty substantially amplifies the weight of both accurate and inaccurate beliefs, thereby intensifying attitudes and amplifying polarization. These findings highlight the role of belief certainty in shaping political judgments and offer a methodological pathway for researchers to model the interplay of multiple correlated political beliefs in an era of abundant—sometimes erroneous—information.\n"]