Even in the best of both worlds, you can't have it all: How German voters navigate the trilemma of mixed-member proportionality

The growing fragmentation of party systems confronts mixed-member proportional electoral systems with a trilemma. Combining the goals of proportionality and of a guaranteed representation of district winners makes it ever more difficult to also achieve a third goal: the fixed size of parliament. Against the background of electoral reform in Germany, this paper studies how citizens position themselves in this trilemma. Using original survey data, we find that all goals are popular and no combination of goals commands majority support. In a context where institutional reform becomes politicized, the trilemma is thus not only a logical, but also an empirical constraint. Moreover, abstract preferences in the trilemma systematically predict how voters evaluate the status quo and specific reform proposals. At the same time, voters are receptive to the logical constraints of the system: Informing respondents about the trilemma trade-offs in an experimental setting makes them more accepting of reform proposals.