Pieces of the puzzle? Coalition formation and tangential preferences

Dumont, Patrick; Falco-Gimeno, Albert; Indridason, Indridi H.; Bischof, Daniel

Abstract

The similarity of parties’ policy preferences has long been considered an important determinant of whether they form a government coalition. That similarity has typically been taken to mean that the parties are in close proximity in some policy space. Policy preferences are, however, only partially described by the parties’ location in the policy space: the degree to which parties care about different issues may also vary. Parties that care about different issues may actually be the most compatible partners, as their tangential preferences would allow them to engage in policy logrolling and enable them to preserve their distinctiveness in the eyes of voters. We test arguments regarding the role of tangentiality and its interaction with policy proximity on the party composition of governments formed in Western Europe from 1945 to 2019. Contrary to our main hypothesis, we find that parties that emphasize the same issues are more natural coalition partners. However, we show that this effect disappears as parties’ ideological differences grow, and that the tangentiality of their preferences would actually help quite distant parties form coalitions together.