From Academic Kids
A coalition government, or coalition cabinet, is a cabinet in parliamentary government in which several parties cooperate. The usual reason for this arrangement is that no party on its own has a majority in the parliament. In times of crisis such as a war or a major economic or political crisis parties may form an all-party National Unity Government.
Cabinets based on a coalition with majority in the parliament ideally are more stable and longlived than minority cabinets. While the former are prone to internal struggles, they have less reason to fear votes of non confidence, although majority governments based on a single party are usually even more stable as long as its majority can be maintained.
Coalition cabinets are common in countries where the parliament is proportionally representative for several political parties. It does not appear at all in countries where the cabinet is chosen by the president rather than the lower house (such as France, the United States and Russia). Countries that often have a coalition cabinet include the Nordic countries, the Benelux countries, Germany, Italy, Turkey, Israel and India. Switzerland has been ruled by a loose coalition of the four strongest parties in parliament since 1959, called the "Magic Formula". Sometimes a coalition government is also created in times of large difficulties, for example war, to give the government a high degree of political legitimacy and acceptability diminishing internal political strife.
To deal with a situation where no clear majorities appear, parties either form coalition cabinets, supported by a parliamentary majority, or minority cabinets which can consist of one or several parties.
In Germany, for instance, coalitions are the norm as it is rare for either the CDU/CSU or SPD to win a majority of their own. Thus coalitions are formed with at least one of the smaller parties. Helmut Kohl's CDU governed for years in coalition with the FDP, Gerhard Schröder's SPD today is in a coalition with the Greens. If a coalition collapses a confidence vote is held. Only once has the government lost a confidence vote.
A similar situation exists in Israel with its dozens of parties. The centre-right Likud thus forms coalitions with far right and orthodox groups, while Labour allies itself with more leftist and pacifist parties.
In both countries, grand coalitions of the two large parties also occur, but these are rarer and large parties usually prefer to associate with small ones.
A coalition can consist of any number of parties. In Germany, a coalition rarely consists of more than two parties (i.e. if we count CDU and CSU as one party), while in Belgium, where there are separate Dutch language and French language parties for each political group, coalitions of six parties are quite common. India's governing coalition, the National Democratic Alliance, consists of thirteen different parties. Finland experienced her most stable government since the independence with a five-party coalition established in the 1990s.
In Australia, the conservative Liberal and National parties are united in an effectively permanent coalition. This coalition has become so stable (at least at a Federal) level and so permanent, that in effect Australia has a two-party system.
In the United Kingdom, coalition governments (known as National Governments) have since 1915 only been appointed at times of national crisis. The most prominent was the National Government of 1931-1940. In other circumstances when no party has had a majority, minority governments have been the rule.
Arguments for and against coalition government
Coalition governments often occur in countries that possess an electoral system based upon proportional representation. Advocates of PR suggest that a coalition government leads to more consensual politics, in that a government comprised of differing parties (often based on different ideologies) would have to concur in regards to governmental policy. Another advantage is that a coalition government better reflects the popular opinion of the electorate within a country.
People who disapprove of coalition governments believe that such governments have a tendency to be fractous and prone to disharmony. This is because coalitions would be comprised of different parties with differing beliefs, who may not always agree on the correct path for governmental policy.