Science in Party Policy Shifts: A Double Edged Sword?

Policy shifts are inherently risky for political parties, as voters often perceive such changes as inconsistent or strategic, leading to electoral punishment and declining acceptance of the decision. At the same time, science enjoys a particular credibility among citizens, commonly referred to as epistemic legitimacy. Citizens increasingly demand evidence-based policymaking and are willing to delegate decision-making authority to experts, especially in times of crisis. This project investigates whether scientific framing by parties can serve as a mechanism to reduce electoral costs and increase acceptance for the decision made by political parties, and whether this can be achieved without undermining the legitimacy of science itself. This study employs a vignette experiment in which respondents read a fictitious news article describing a political party that either maintains or changes its policy position. The experimental manipulation consists of two dimensions: (1) whether a policy shift occurs, and (2) whether the decision is framed as supported by scientific experts, resulting in four experimental groups. Each vignette was applied to two issue domains: a pragmatic issue (taxes on wages) and a principle issue (abortion). We focus on two central consequences: policy shift acceptance and voting intention for the political parties on the one hand, and perceptions of scientific competence and independence on the other. Based on this, the study contributes to understanding whether expertise can be mobilized in party communication without eroding trust in science.