Two-Party System

A TWO-PARTY SYSTEM is found in democracies such as Great Britain and the United States, where only two parties gain the vast majority of votes and offices at all levels of government. Two-party systems are rare outside Great Britain and former British colonies; they are typically associated with a relatively simple cleavage structure and single-member district plurality elections.

Proponents praise the simplicity of such a system, arguing that it ensures governmental stability, it indicates clearly where responsibility lies, and has a moderating influence over the main political actors. In a parliamentary system, in addition to making the choice easier for voters, the two-party system is considered more democratic because it gives voters an opportunity to choose the government, unlike multiparty systems where government is the result of post-election negotiations among party leaders. Critics say that a two-party system limits representation and the range of policies considered for enactment.

There is more than one kind of two-party system; British two-partyism is very different from the American two-partyism. The institutional context is crucial for how a two-party system actually works and for its effects on policymaking. The key distinction here is between America's presidential system and Britain's parliamentary system. Although the logic of a two-party system is inherently majoritarian, the existence of separation of powers opens the door for divided government. This can mitigate the winner-takes-all effect of the two-party system when, as it is often the case in the United States, one party is in control of Congress and the other party controls the White House. The British parliamentary system, with its fusion of legislative and executive powers, prevents such an occurrence. In a parliamentary regime, a two-party system means that the party that has a majority in the legislature is also forming the government. Such single-party governments have a higher life expectancy than multiparty governments.

Party discipline is another important difference between the British and the American two-party system, and is largely a result of the different institutional incentives provided by presidentialism and parliamentarism. In Britain, the prime minister is also the leader of the legislative majority, and therefore has the means to ensure the compliance of the rank-and-file members of parliament representing the majority [Page 805]party. Parties select the candidates for office, as in other European nations. British parties are centralized and disciplined, and representatives from the same party tend to vote as a bloc. Those who follow the party line enhance their chances for being rewarded in the future with a better position in the government, and party dissidence is rare.

American parties are decentralized and undisciplined; party dissent is more common than in Britain. Thus, unlike the impact of parliamentarism in Britain, which maintains the cohesiveness of the two major parties, American-style presidentialism has somewhat contradictory effects on the party system. It reinforces the existing two-party system, as only the two major parties have a chance to capture the most important office, but it weakens the two parties, because it lacks the additional incentive (the fusion between legislative and executive power) that makes their British counterparts so disciplined and cohesive. Finally, having the candidates for office selected through primary elections, rather than party organizations, as in Britain, further enhances the independence of office holders.

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