Two-party system

A two-party system is a form of party system where two major political parties dominate voting in nearly all elections. As a result, all, or nearly all, elected offices end up being held by candidates endorsed by one of the two major parties. Coalition governments occur only rarely in two-party systems, though each party may internally look like a coalition.

Under a two-party system, one of the two parties typically holds a majority in the legislature (or a legislative house in a bicameral system), and is referred to as the majority party. The other party is referred to as the minority party.

Notable examples of countries with "two party systems" include the United States,and Jamaica. Some countries that feature weak third or fourth parties, such as the United Kingdom, Canada, Spain,Malaysia and Australia are often thought of as being two party states as well, as actual governance of the country may be dominated by only two parties even though other parties may have reasonable bases of support.

Generally, a two party system becomes a dichotomous division of the political spectrum with an ostensibly right and left party, Tories vs. Labour in some commonwealth countries, Republicans vs. Democrats in the US, etc.

How and why it occurs

Often general elections have rules that allow any number of candidates to be placed on a final ballot as long as those candidates meet some minimum requirements, often based on signatures of support gathered. This type of general election promotes coalition building outside of the election process. These coalitions or political factions have, over time, become formalized associations called political parties with rules and procedures for selecting the candidate most likely to win in order to put forward the strongest candidate for the General Election. In such a system the two most well organized and unified parties will ultimately have recurring success. Since there can only be two successful parties, then the two parties often become more like coalitions of factions that would have otherwise been their own discrete parties in other electoral systems. These unified parties are held together despite their differences because their common political beliefs outweigh their differences and because of the threat of vote splitting.

Vote splitting can affect the outcome of an election when a plurality and not majority is required to win. In this scenario, two candidates which may represent a majority political viewpoint both receive votes that would have otherwise gone to the other candidate, thus "throwing" the election to a candidate that may have received far less than majority support. A Two-round system with a non partisan primary reduces concerns over vote splitting, because the top two candidates' names from the primary will be printed on the final ballot. In this scenario, the voter still has an opportunity for tactical voting to select the better candidate in the final election.

Two-party systems, by their nature, allow third parties to occasionally arise, gain support and ultimately supplant one of the two major parties. This is the scenario that occurred when the Labour Party replaced the Liberal Party in the 20th century United Kingdom and when the Republican Party replaced the Whigs in the 19th century United States. Under Duverger's law third parties may rise to prominence within the two-party system but only at the ultimate expense of one of the two former major parties. The system re-stabilizes into two-party mode after a three-party interlude.

In countries that use proportional representation (PR), especially where the whole country forms a single constituency (like Israel), the electoral rules discourage a two-party system; the number of votes received for a party relates directly and proportionally to the number of representative seats won, and new parties can thus develop an immediate electoral niche. Duverger identified that the use of proportional representation would make a two party system less likely.

How it began in the U.S.

America's first President George Washington, did not belong to a political party. He believed they did not best serve the people's interests. This made him America's only President who was elected as an independent (not affiliated with a party), though John Tyler was expelled from his party a few months after taking office. Most of America's founding fathers were opposed to political parties, and wanted none of them in the U.S.

America's first political party was the Federalist Party founded by Alexander Hamilton in 1792. The Federalists favored a strong central government ruled by a wealthy educated elite, large cities with powerful industry, a national bank, strong military, treaty with Britain, and fewer rights for states and most citizens. Federalists controlled the government until 1801. George Washington supported many Federalist policies. America's second President, John Adams, was a member of the Federalist Party.

America's second political party was the Democratic-Republican Party, founded by Thomas Jefferson and James Madison in 1792 in order to oppose the policies of the Federalists. The emergence of the Democratic-Republican Party marked the beginning of the U.S. two-party system. Jefferson was reluctant to create a party because he was opposed to political parties in general because of their power struggles for control of the government, but he felt that founding an opposition party was the best way to protect the rights of citizens from the consolidation of power in the federal government that the Federalists favored. The Democratic-Republican Party opposed the treaty with Britain, favored an agriculture-driven economy, spoke out against the Constitution (largely due to its initial vagueness and ambiguity), denounced the national bank, and promoted citizen's and states' rights. It became the dominant political party in the United States from 1800 until the 1820s, when it split into competing factions, one of which became the modern-day Democratic Party.

Therefore, the two party system in the U.S. occurred to prevent one party from gaining too much power, by creating a second party with opposite policies.

Advantages and disadvantages

The two-party system's defenders argue that:

• Uncommon and unconventional ideas remain non-influential, so policies and governments do not change rapidly. While smaller parties find this exceptionally frustrating, proponents of the two-party system suggest that it enhances stability while eventually allowing for ideas that gain favor to become politically influential.
• Bickering of narrowly based ideological factions in multi-party systems can lead to a torpid legislative process. These factions, if they gain enough influence via winning seats, can adopt a "by any means necessary" mentality of furthering their agenda which can include purposely blocking or delaying important legislation.
• Two-party systems offer stronger, majority governments which can pass needed legislation without the fetterence of minor parties.

People against the two-party system argue that:

• Narrowly based ideological factions can force the major parties to help them in exchange for their support. This can create a chaotic and fluctuating system of alliances that intensifies confusion among voters. Additionally, this "tie-breaker" influence minor parties achieve can serve to undermine the true positions of the major parties.
• The ruling party's majority may still be based on a smaller segment of the population than coalition governments due to lower turnout, and votes cast that do not lead to the desired representative [1]. The majority of this body (20% plus one) rules the nation. [2]
• Legislative representation can skew wildly from the actual percentage of the vote a party wins. For example, the party with the second-highest total vote tally actually won a parliamentary majority in the 1847, 1852, 1874, and 1951 UK general elections, and the most seats in the January 1910, December 1910, 1929, and February 1974 elections.
• Elections based on geographical district representation can become subject to gerrymandering.
• Two-way elections encourage people to run negative campaigns.
• If one of the two parties becomes weak, a dominant-party system may develop. In fact, a dominant party system has developed in almost every single country that has used first past the post (FPTP), at least at a regional level. In the US, the Democrats often landslided in the southern portion up until the late 20th century, winning almost every seat available in most states in a phenomenon known as the Solid South. Mexico had a dominant party system until constitutional reforms added fairer proportional representation to the scheme.
• Campaign contributions can more easily corrupt a two-party system - since it has fewer players to receive donations.
• In an effort to attract voters, each party will adopt planks of the other party's platform, leading to the appearance in some skeptics' minds of a one-party system. Examples include the American notion of a "Republicrat".
• In The Federalist No. 10, James Madison decried the liability of representative legislatures to be controlled by single factions holding a majority of the seats. Madison argues that because getting rid of factions is nearly impossible and leads to highly undesirable side-effects, ensuring that all factions are represented reduces the likelihood that any one faction will control all of the seats and institute any and all changes they desire, thus preventing majority tyranny. A two-party system often leads to one faction winning a majority of the seats and governing without compromise. A multi-party system or proportional non-partisan system could be more consensus-based, allowing for laws to be passed less hastily and with more sincere debate on the issues.
• In the plurality system which encourages two-party system, most voters have perforce to engage in tactical voting, voting for candidates that may not be their first choice - either to help a perceived potential "winner" or to block a potential enemy.
• Smaller parties suffer from under-representation: they will not receive a number of seats in the country's assembly that reflects the number of votes they receive (and therefore the amount of support they could or do receive). Some see this as undemocratic, arguing that citizens who vote for small parties should receive fair representation. Others see it as fair to discourage unpopular opinions.
• In a dichotomized system, voters only get one more choice than they would under a totalitarian regime.
• Special interests can establish a lock on political discourse, media, etc. and establish a narrow dominant ideology which both parties serve so that in effect it is a one-party system tending to corporatism.