Two-party system

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One speaks of a two-party system or two-party democracy when essentially two parties alternate as governing parties in a democratic state . This is strongly favored by a relatively homogeneous electorate and majority voting rights (a presumed legality, which is called Duverger's law after its founder ).


The Italian political scientist Giovanni Sartori identified the following four characteristics of a two-party system:

  1. Each of the two major parties is able to achieve an absolute majority of the seats in parliament
  2. In general elections, one of the two major parties receives a parliamentary majority
  3. This party is ready to rule alone
  4. There is a relatively high probability that power between the two major parties will shift through elections over time.

The model of the median voter describes that in two-party systems the programs of the parties tend towards the middle over time. Two-party systems are a practical example of the ice-cream-seller-on-the-beach problem in game theory .


A major advantage of the two-party system is the normally secure parliamentary majority of the respective governing party. As a result, the government is stable and early elections are seldom necessary. The difficulty in obtaining parliamentary representation for minority interests is seen as a disadvantage. If one of the parties breaks up or a strong new party emerges, the majority formation becomes almost accidental until the system stabilizes again through the demise of the new or an old party.

In the area of ​​political decision-making in a democracy, the philosopher Slavoj Žižek criticizes the two-party system as an alleged option that basically does not exist.

Case studies


In Great Britain, where majority voting applies, the Whigs (from 1859 Liberal Party ) and the Tories have been the two dominant parties for centuries . After the First World War they were replaced by the Conservative Party and the Labor Party . In the general election in February 1974 , however, no absolute majority and no coalition were formed. In 2010 a conservative- liberal-democratic coalition was formed.

Favored by the electoral system of Malta , the Nationalist Party and the Malta Labor Party dominate there .

From the parliamentary elections in Greece in 1990 , either the Panellinio Sosialistiko Kinima or the Nea Dimokratia achieved an absolute majority in every election, until parties like Syriza also received significant votes in the elections in May and June 2012 . The elections in January 2015 were finally won by a third party, Syriza, as was the early elections in September of the same year.


In the parliamentary elections in Mozambique in 1994 , in which several parties were allowed for the first time, FRELIMO won just ahead of RENAMO ; smaller parties had little or no influence. In the subsequent elections, FRELIMO was able to extend its lead.

Since the parliamentary elections in Cape Verde in 1991 , the Movimento para a Democracia or the Partido Africano da Independência de Cabo Verde have always had an absolute majority in the National Assembly .


Distribution of seats in the 112th US House of Representatives: All seats went to Republicans (red) or Democrats (blue).

There is a two-party system in the United States , where only the Democratic and Republican parties have had practical significance since the mid-19th century . Before that there were other parties, and even later some tried again and again to establish third parties as alternatives, but mostly there were only two large parties.

In Honduras , the Partido Nacional de Honduras and the Partido Liberal de Honduras are traditionally the strongest parties. However, in the parliamentary elections in 2001 and 2005, none of the parties achieved an absolute majority because three smaller parties also entered the National Congress .

In 1973, several opposition parties joined together in Belize to form the United Democratic Party to counterbalance the ruling People's United Party . Since then, only these two parties have been represented in the House of Representatives .

In the National Assembly of Guyana dominate People's Progressive Party (PPP) and the People's National Congress (PNC). In the 2001 parliamentary elections , however, the PPP remained just below the absolute majority.


Individual evidence

  1. Slavoj Žižek: Why do we all love to hate Haider? ( Memento of the original from March 14, 2005 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. In: Eurozine , October 3, 2000. @1@ 2Template: Webachiv / IABot /