The two faces of issue polarisation and their impact on party competition in Western Europe

While polarisation is on the rise in Western Europe, there is little descriptive evidence about which issues divide voters and how. There are even fewer studies that seek to explain how party salience strategies respond to polarising issues. This study addresses these gaps, underscoring a conceptual distinction that is often missed in the literature on issue competition — namely, that issues can divide the electorate at large (‘general issue polarisation’), or according to the party they support (‘party issue polarisation’). Survey data about voter preferences in six Western European countries shows that the correlation between these two types of issue polarisation is weak. For example, while some cultural issues like soft drug policy and same-sex marriage are highly polarising in general, they do not divide supporters of opposing parties so much. Using party Twitter activity as the dependent variable, it is shown that parties put less emphasis on issues the more extreme voter preferences are, running contrary to predictions based on prior work. By contrast, issues higher in party polarisation received more attention. This study highlights the importance of taking a multidimensional approach to issue polarisation, and calls for more refined theories of how parties deal with polarising issues.