Dimensionality and the number of parties in legislative elections

This article explores how the party-defined dimensionality of political competition relates to the number of parties competing in legislative elections. It demonstrates that a mathematical relationship between the number of electoral parties and the literature’s concept of dimensionality follows from the variables’ definitions; conversely, it argues that exploring the relationship between the number of electoral parties and a different concept of dimensionality conveys new information. Hence, it first argues that how we conceptualize dimensionality matters. Redirecting attention to the latter relationship, it then hypothesizes that party system fragmentation will go hand-in-hand with the appearance of new conflicts on the political agenda when the electoral system is permissive. Using a time-series cross-sectional dataset that includes at its core a new measure of dimensionality, it finds reasonable support for the hypotheses; however, at the elite level, new parties are found to play less of a role in politicizing new conflicts than expected.