¹ Lipset, Seymour Martin and Rokkan, Stein, Party Systems and Voter Alignments: Cross-NationalPerspective (NewYork: Free Press, 1967), 112Google Scholar.

² Ibid, 117.

³ Ibid., 112.

⁴ Sartori, Giovanni, Parties and Party Systems: A Framework for Analysis (Cambridge: Cambridge University Press, 1976), 176Google Scholar.

⁵ Evans, Geoffrey and Whitefleld, Stephen, “Identifying the Basis of Party Competition in Eastern Europe,” British Journal of Political Science 23 (1993)CrossRefGoogle Scholar.

⁶ Kitschelt, Herbert, “The Formation of Party Systems in East-Central Europe,” Politics and Society 20 (1992)CrossRefGoogle Scholar.

⁷ The classification of Kitschelt's argument as representing the weak version of social cleavage theory is not entirely correct. While consistent with the weak version, Kitschelt ascribes even more influence to political elites. He persuasively maintains that on occasion politicians enter into conflicts that do not reflect underlying social cleavages. This is an important insight. As an example of such conflicts, consider the Eastern European debates over the pace of economic reforms or the Russian debates over war against irridentist regions, or the Czech, Hungarian, and Polish debates over their entry into the European Union. All of these are instances of critical, “one-shot” decisions that may or may not map themselves onto underlying social cleavages. From the perspective of social cleavage theory, these decisions constitute exogenous shocks that temporarily perturb the political system. Over time, however, as these one-shot decisions are made (economic reforms are completed, wars are ended, accession treaties signed), the political salience of these issues subsides and the system reverts to its steady state, where political oppositions reflect underlying social tensions.

⁸ This question should also interest scholars of Western Europe who study the politicization of the environmental cleavage.

⁹ Lipset and Rokkan (fn. 1), 101.

¹⁰ In this context the definition of a group as a set of individuals who share similar opinions on all divisive issues is quite flexible. It allows us to construct larger political categories that consist of several groups. Thus, for example, we can think of a “religious camp” that includes Catholic landowners and Catholic peasants. While all members of this camp share a similar opinion about religion, they might differ in their views about other issues, for instance, about land reform.

¹¹ Political opposition is not synonymous with any conflict among political parties. Rather, it denotes an intraparty conflict that mirrors an underlying social tension. To see the distinction, consider a party system that consists of three parties π₁, π₂, π₃ and imagine that on some issue x, these parties take positions p (π₁, x ) = −1/2, p (π₂, x ) =1/2 and p (π₃, x ) = 1. From definition 2, we get that a political opposition separates party π₁, from parties π₂ and π₃ Notice, however, that there is no political opposition between parties π₂ and π₃ even though their positions on issue x are different. The substantive reason for this distinction flows from definition 3, which relates social cleavages to political oppositions and thus restricts the meaning of political opposition to a conflict rooted in a social tension.

¹² It is important to differentiate between political opposition and polarization understood as the distance that separates political parties on a given issue. To see the distinction, consider a party system that consists of two parties π₁ and π₂ and imagine that on some issue x these two parties take positions p (π₁, x ) = a and p (π₂, x ) = – a where a > 0. According to definition 2, a political opposition separates these two parties regardless of the value of a, that is, irrespective of the distance (2a ) between the two parties. Yet the distance between them is important because it can be interpreted as the polarization or intensity of political conflict. For values of a close to 1, the conflict on issue x is highly polarized, while for values of a close to 0, the conflict becomes relatively attenuated.

¹³ This result has an interesting implication for students of established democracies who study the politicization of the environmental cleavage because it implies that it is possible, albeit difficult, to politicize that cleavage without the formation of green parties.

¹⁴ Lipset and Rokkan (fn. 1).

¹⁵ To be clear, the word “compete” denotes a decision to contest a given election. The word “with-draw” denotes a decision not to contest that election. In contrast, the phrases “leave the game” and “enter the game” denote the automatic replacement of politicians who choose to withdraw with new politicians who then make their own decisions.

¹⁶ Duverger, Maurice, Political Parties (London: Methuen, 1954)Google Scholar.

¹⁷ Cox, Cary, Making Votes Count: Strategic Coordination in the World's Electoral Systems (Cambridge: Cambridge University Press, 1996)Google Scholar.

¹⁸ In fact, Cox was the first one to suggest that fragmentation of party systems in Eastern Europe can be analyzed as a coordination problem.

¹⁹ To ground this hypothetical scenario in reality, consider the example of Poland. The country has a large farming population and an old agrarian party (PSL) that traces its roots to the late nineteenth century. Recent opinion polls suggest, however, that the party is only slightly above the 5 percent legal threshold necessary to gain parliamentary seats. Among other things, the party faces competition from parties that appeal to farmers on religious grounds. Should PSL be eliminated from electoral politics, Poland would continue to have a pronounced urban-rural cleavage, but this cleavage would no longer be politicized.

²⁰ Without additional assumptions, the elimination of the Christian democratic candidate can lead to an indeterminate outcome.

²¹ Poole, Keith and Rosenthal, Howard, Congress: A Political Economic History of Roll Call Voting (New York: Oxford University Press, 1997)Google Scholar.

²² Kitschelt, Herbert, The Logics of Party Formation (Ithaca, N.Y.: Cornell University Press, 1989)Google Scholar.

²³ Klingeman, Hans-Dieter, Hofferbert, Richard, and Budge, Ian, Parties, Policies, and Democracy (Boulder, Colo.: Westview Press, 1994)Google Scholar.

²⁴ Lipset, Seymour Martin and Marks, Gary, It Did Not Happen Here: Why Socialism Failed in the United States (New York: Norton, 2000)Google Scholar.