This chapter takes issue with the dominant notion that political polarization can be understood as a process through which parties diverge on a single dimension of political conflict. Rather, I introduce the notion that affective political polarization intensifies when new issue dimensions are added. In a two-party system, the parties will appear to be moving further from the average voter, and further from one another, if they offer ever-more heterogeneous and incoherent bundles of platforms over time as new issues are politicized. In the United States, as a result, increasing hostility toward the out-party goes hand in hand with increased ambivalence about the in-party. Meanwhile, the parties become increasingly internally fractious. In a multiparty system, on the other hand, when new issues emerge, parties can position themselves throughout the multidimensional issue space. As a result, voters feel closer not only to their in-party but also to the average out-party. In this way, I suggest that multiparty systems can reduce overall levels of affective polarization.

Political polarization in the United States causes inefficiency and policy uncertainty. This occurs not because of unusually high levels of ideological polarization among voters or legislators that generate large policy swings. Rather, it is a problem of extreme gridlock under a unique form of two-party presidential democracy in which changes from the status quo frequently require defections from opposition legislators.

This chapter explores the argument that these defections are increasingly difficult to achieve because of a profound transformation of American political geography associated with deindustrialization and suburbanization. Our understanding of this transformation is still limited, as should be the hubris with which we dispense reform advice. This chapter advocates a cautious and experimental approach to reform at the state level, focusing on the potential advantages of some form of compulsory voting.

WHAT IS THE PROBLEM?

The United States has a unique constitution. It is one of the only countries in the world that combines a strict two-party system with a presidential form of government. Its only peers are Venezuela, Ghana, and Sierra Leone. As demonstrated in Figure 7.1, all other former British colonies with singlemember districts and strict two-party systems have a parliamentary form of government. These countries have no need for bipartisanship. Members of the government party almost always vote for the legislative proposals of the executive, and members of the opposition vote against. A bimodal distribution of roll-call voting scores without centrists is neither remarkable nor troubling in a parliamentary system.

The problem in the United States is that for two-thirds of the years since 1950, the president has not presided over a partisan legislative majority. To achieve any change from the status quo, the president must assemble the votes not only of co-partisans but also of some members of the opposition party. In most other presidential systems, the chief executive is able to assemble multiparty coalitions rather than relying on defections from a single opposition party that controls the legislative agenda.

Like a fashion trend traveling from New York to the heartland, soul-searching about causality has made its way from empirical research in economics to that in political science with the usual lag. Gone are the days when it was enough to have a nice theory, a conditional correlation, and some rhetoric about the implausibility of competing explanations while implying but assiduously avoiding the “c” word. Editors, reviewers, and search committees are beginning to look for more explicit and careful empirical treatments of causality. That is, following a definition of causality tracing back to Mill (1848), researchers are expected to lay out a set of possible outcomes, or counterfactuals, generated by a set of determinants, and demonstrate that holding all possible determinants except one at a constant level, the manipulation of that determinant is associated with a specific change in outcome, which can be deemed a causal effect (Heckman 2005).

It does not take much soul-searching to realize, however, that the observational studies that make up the vast majority of empirical explorations in comparative politics are deeply flawed when held up to the experimental ideal. Where does this leave us? In the extreme view, if we cannot do randomized field experiments or perhaps survey experiments, we should do nothing. The opposite extreme position holds that this would remake comparative politics into an arid subfield of program evaluation, turning a blind eye to the interesting and important questions that animated the field in its golden era (definitions vary).