HKS Authors

See citation below for complete author information.


Jean Blondel made many lasting contributions toward comparative politics, not least in his classification of party systems in Western democracies. Yet during the 5 decades since Blondel’s original contribution, party competition has been transformed by multiple developments, including changes in the grassroots electorate, as intermediary organizations connecting citizens and the state, and at the apex in legislatures and government. Does Blondel’s typology of party systems remain relevant today—or does it require substantial revision? And, does party system fragmentation predict ideological polarization? Part I sets out the theoretical framework. Part II compares trends from 1960 to 2020 in party system fragmentation in a wide range of democracies, measured by the effective number of parties in the electorate and in parliament. Not surprisingly, the effective number of electoral parties (ENEP) has generally grown in each country across Western democracies. This does not imply, however, that party systems are necessarily more polarized ideologically. Part III examines polarization in party systems across Western democracies, measured by standard deviations around the mean of several ideological values and issue positions in each country. The findings suggest that party system fractionalization and polarization should be treated as two distinct and unrelated dimensions of party competition. The conclusion reflects on the broader implications of the findings for understanding party polarization and threats of backsliding in democratic states.


Norris, Pippa. "“Things fall apart, the center cannot hold”: fractionalized and polarized party systems in Western democracies." European Political Science (31 January 2024).