Things Aren’t Going That Well Over There Either: Party Polarization and Election Law in Comparative Perspective


One of, if not the, most important change in American political life over the last 30 or so years has been the rise of extreme party polarization. Our two major parties are increasingly ideological distinct and distant from one another, and increasingly willing to abandon long-standing institutional norms and short-term policy compromise in the name of achieving long-run party goals. Efforts to understand why the parties have changed largely have been parochial, largely looking for explanations in American politics, history, media and institutional arrangements.  This focus has a logic to it. Politics in most other advanced democracies does not feature the same type of polarization between parties, and therefore the answers for why American politics has gone in this direction seem to lie inward rather than abroad.   

But it is still a mistake. This short essay argues that a common shift in voter preferences towards more radical and fundamentalist opinion among even a small slice of the electorate can explain polarization in the United States and changes in politics abroad. In many European countries with proportional representation (PR), we have seen the rise of parties so radical that established parties refuse to form coalitions with them. In “Westminster” systems, which due to their use of first-past-the-post vote counting and single-member districts are supposed to tend towards having two parties, we have seen the rise in third-and fourth party voting. Notably, in most Westminster systems, there is little intra-party democracy, leading groups of voters with more radical opinions without the ability to influence mainstream parties, which makes those with radical opinions more willing to waste votes. A plausible story about American political development is that the same voters and interest groups who would form radical parties in PR systems and support spoilers in Westminster systems use intraparty democracy to influence our two-party system and create polarization. Election laws and institutional design shape the way radicalism influences politics. 

If this is right, several lessons follow. Any effort to understand why American parties have changed must look at factors that are common across many western democracies. Further, the rise of radical parties in PR systems and spoilers in Westminster systems have created governance problems that are of a type with the problems created by our extreme polarization. We should thus be skeptical that there are institutional design reforms that can make American governance work easily in the face of polarization.