When voters support parties in multi-party democracies it is often uncertain what coalition government the party is likely to join. Are voters adversely affected by this type of uncertainty? In this paper, we present observational and experimental results that support the idea that voters are risk averse when considering coalition government options.

Excluding extremist parties from forming governments, i.e., establishing cordons sanitaires against extremist parties, can be a decisive contribution to safeguarding democracy. The destruction of the Weimar Republic and the rise of Nazism in the 1930s serve as anecdotal evidence for this claim, as there was no such cordon sanitaire against the Nazi Party and other extremist parties in Germany. Could a cordon sanitaire against extremist parties have changed the fate of the 1930s Weimar Republic? Cordons sanitares are specific coalition signals, and we can use existing theoretical knowledge about the effects of these signals to assess the question at hand. I integrate these theoretical insights into a formal agent-based model of party competition with coalition-directed voters and perform counterfactual simulations in an artificial 1930s Weimar Republic.

This study shows that coalition signals affect voting decisions by changing voters’ expectations about which coalitions are likely to form after the election. Moreover, this paper provides the first integrative overview of different mechanisms that link coalition signals and individual voting behavior.

This study formulates and tests an agent-based model of opinion dynamics which claims to explain the evolution of political preferences by means of social interaction effects.