question: Why the US has only two major political parties, unlike countries like India and the U.K., where small parties are influential because they help to make coalition governments.
comment: Duverger's law basically says that any country that has a first past the post electoral system will have a two party system. The US has an extreme form of first past the post electoral system where the system is first past the post all the way from the very top (and a directly elected president is a big part of it) all the way down to the very local level. This is combined with a very high bar to enter politics (well established strong party machines, a very money and fundraising oriented electoral process which means the big two can always outspend you, rules to prevent people delivering leaflets door to door, weak trade unions etc...) and together it makes it virtually impossible for third parties to break through. It's funny that you mention India and the UK as the example because they're actually the only exceptions to Duvergers' law (well them and Canada) in that they have first past the post systems but they have less of a two party system. However they're not true exceptions: - they're mostly two party systems. Lab an Con dominate the UK, Congress and BJP dominate India. The third parties are pretty tiny and inconsequential all things considered. "miniscule" is a fair description of third parties in India and the UK - they're countries with highly regional politics and the successful third parties are regional parties ie the SNP in Scotland and AIADMK in Tamil Nadu - we're currently living through weird times. For example there was no coalition government in the UK between ww2 and 2010, and ww2 only had one because of ww2, they didn't need one. The time we're living through now is the exception not the rule But yeah most of the rest of the world has proportional representation and multi party democracy
passages: For electoral rules, it is postulated that a few large parties tend to prefer small assemblies, small district magnitudes (the smallest being one), and rules based on small quotas of votes for allocating seats (the smallest being simple plurality, which does not require any specific threshold), while multiple small parties tend to prefer large assemblies, large district magnitudes, and large quotas (like those of proportional representation: within proportional representation systems, given the same number of seats, systems with a higher quota such as Hare or Sainte-Laguë favour smaller parties, while systems with a lower quota such as Droop or D'Hondt favour larger parties). Large parties may prefer small institutions in order to exclude others from competition, while small parties prefer large institutions able to include them within. More specifically, political configurations in which there is a single dominant party or two rather balanced parties tend to produce choices in favor of rather restrictive or exclusionary electoral systems, such as those based on plurality rule in single-member districts, while settings with multiple parties tend to support choices in favor of more inclusive electoral formulas, such as those using rules of proportional representation.
   There are also cases where the principle appears to have an effect, but weakly:
  
  BULLET::::- In India, there are 38 political parties represented in the Parliament. Like the UK and Canada, India has a winner-takes-all system. Most of the Indian parties are allied with one of two larger electoral coalitions which makes the Indian system functionally somewhat like a two-party system.
   Australia, Canada, Nepal, Pakistan, India, Ireland, United Kingdom and Norway are examples of countries with two strong parties and additional smaller parties that have also obtained representation. The smaller or "third" parties may hold the balance of power in a parliamentary system, and thus may be invited to form a part of a coalition government together with one of the larger parties, or may provide a supply and confidence agreement to the government; or may instead act independently from the dominant parties.
   Another criticism is that the dominant parties in plurality/majoritarian systems, often looked on as "coalitions" or as "broad churches", can fragment under PR as the election of candidates from smaller groups becomes possible. Israel, again, and Brazil and Italy are examples. However, research shows, in general, there is only a marginal increase in the number of parties in parliament.
  
  Open list systems and STV, the only prominent PR system which does not require political parties, enable independent candidates to be elected. In Ireland, on average, about six independent candidates have been elected each parliament.
   Small states can under some circumstances have a disproportionately great influence. According to Diana Panke, "Small states tend to be most likely to punch above their weight if the negotiations take place in an institutionalised arena with majority-based decision-making rules in which each state has one vote or in contexts in which decisions are made unanimously, if they are selective in negotiations and concentrate their capacities on the most important issues, engage in capacity-building activities to maximise their ideational resources, if they make use of institutional opportunity structures such as chairing meetings and engaging in agenda-setting, and if they individually or collectively apply persuasion strategies from early on".
   This has been seen as an upside-down reading of Duverger's laws holding that a plurality rule election systems tend to favor a two-party system, while proportional representation tends to multipartism. By suggesting, in contrast, that electoral systems are an effect of party systems rather than a cause, it has been shown that changes from a plurality system to a proportional system are typically preceded by the emergence of more than two parties, and are typically not followed by a substantial increase in the number of parties. Existing parties tend, thus, to choose electoral systems that are able to crystallize or consolidate the previously existing party configurations and systems. More generally, electoral systems and other prominent political institutions can be seen as a consequence of already existing political party systems in assemblies and governments, each of which tends to prefer those institutional formulas and procedures that can consolidate, reinforce or increase their relative strength. 
   Argentina, Armenia, Austria, Belgium, Brazil, Croatia, Denmark, Finland, France, Germany, Iceland, India, Indonesia, Ireland, Israel, Italy, Lebanon, Maldives, Mexico, Moldova, Nepal, the Netherlands, New Zealand, Norway, Pakistan, the Philippines, Poland, Portugal, Romania, Serbia, Spain, Sri Lanka, Sweden, Switzerland, Taiwan, Tunisia and Ukraine are examples of nations that have used a multi-party system effectively in their democracies. In these countries, usually no single party has a parliamentary majority by itself. Instead, multiple political parties are compelled to form compromised coalitions for the purpose of developing power blocks and attaining legitimate mandate.
  
  Section::::Comparisons with other party systems.
   The concept of "the median voter" is usually applied to political systems featuring First-past-the-post electoral systems. In these systems, the highest polling candidate is elected to represent each single-member electoral district. This system differs from proportional representation, which features more elaborate voting procedures and multi-member electoral districts. As there can be only one winning candidate in each electoral district in First-past-the-post elections, there is an incentive for voters to support viable candidates and not "waste" their vote on hopefuls who have little chance of success. As a result, it is much harder for smaller parties to gain representation in parliament. Ultimately, there is a tendency for two-party systems to develop, as voters coalesce around potential winning candidates. This tendency is known as Duverger's law. In this kind of political landscape, in which there are two viable political parties, party elites tend to favour "big tent" electoral strategies that appeal to a broad range of the electorate rather than aiming for an ideological niche. While curvilinear disparity is typically associated with the Anglo-American political experience, however, it can theoretically occur in any large party.
   According to a 2017 review study, "What scholars can agree on is that small states generally prefer multilateralism as both a path to influence and a means to restrain larger states. Studies of influential small states indicate that they are able to develop issue-specific power to make up for what they lack in aggregate structural power. Small states can, therefore, develop power disproportionate relative to their size on the few issues of utmost importance to them. In addition to prioritization, small states have successfully employed the strategies of coalition-building and image-building. Even though small state administrations lack the resources of their larger counterparts, their informality, flexibility, and the autonomy of their diplomats can prove advantageous in negotiations and within institutional settings."
   Sub-national entities are often dominated by one party due the area's demographic being on one end of the spectrum. For example, the current elected government of the District of Columbia has been governed by Democrats since its creation in the 1970s, Bavaria by the Christian Social Union since 1957, Madeira by the Social Democrats since 1976, and Alberta by Progressive Conservatives from 1971–2015. On the other hand, where the dominant party rules nationally on a genuinely democratic basis, the opposition may be strong in one or more subnational areas, possibly even constituting a dominant party locally; an example is South Africa, where although the African National Congress is dominant at the national level, the opposition Democratic Alliance is strong to dominant in the Province of Western Cape.
   A size-related obstacle would for example be the EU which uses a system of weighted voting, which gives bigger states a greater political leverage than smaller states. On the other and a lot of International Organisations use a “one state, one vote” principle which may appear to secure equality between states of various sizes. However, even if the formal voting itself is equal what happens in the background is not. Small states face size-related difficulties during negotiation processes in IO’s such as the UN because they often possess fewer administrative, financial and economic resources, which hinders them in participating in the negotiation process at the same level as the larger states. They are simply spread too thin across various issues and therefore resort to concentrating all their resources towards the issue of highest significance. Therefore, small states are forced to choose between their interests in negotiations. They also produce better results if they use persuasion based strategies rather than bargaining ones because they lack bargaining leverage.
   Another possibility is that the major parties may find they have more in common ideologically with each other than with the smaller parties, or that the fragmentation of the smaller parties is so great that no other coalition is stable. Examples include Austria, where the mainstream parties of the left and right have often formed grand coalitions to keep parties of the far left or far right out of government (an example of a "cordon sanitaire"), or Israel, where no single party has ever won enough seats to govern alone, and, in some parliaments, the fragmentation and intransigence of some of the smaller parties has made it easier to maintain a coherent platform with a grand coalition than with a narrow one. This is often done out of political necessity, to prevent an early election.
   The effect of a system based on plurality voting is that the larger parties, and parties with geographically concentrated support, gain a disproportionately large share of seats, while smaller parties with more evenly distributed support are left with a disproportionately small share. It is more likely that a single party will hold a majority of legislative seats. In the United Kingdom, 18 of the 23 general elections since 1922 have produced a single-party majority government; for example, the 2005 general election results were as follows:
   Countries using proportional representation give little advantage to the largest two parties, so they tend to elect many parties. Therefore, in those countries, three, four, or more political parties are usually elected to legislatures. In such parliamentary systems, coalitions often include smaller parties; since they may participate in a coalition government, there is not a sharp distinction with a 'major' party. In two-party systems, on the other hand, only the major parties have a serious chance of forming a government. Similarly, in presidential systems, third-party candidates are rarely elected president.
  
  e
   BULLET::::- Because the majority of voters in a district cannot be shut out of the process as in some plurality elections (where the winning candidate falls short of majority support), coalition-building among non-plurality-winners is possible and effective, both generally and on specific issues.
  
  Section::::Disadvantages.
  
  BULLET::::- Unwieldy, suffers from scalability issues. In the USHR example below, the 435 current members are already considered cumbersome for debate, if each of those seats broke into three, 1,305 would cause logistical issues. This is a best case of only three parties, if it grew to unlimited parties it would quickly reach unreasonable numbers.
   In most Westminster system nations, each constituency elects one member of parliament by simple plurality voting. This system heavily biases the vote towards increasing the number of seats of the top two parties and reducing the seats of smaller parties, a principle known in political science as Duverger's law, and thus minority governments are relatively uncommon. Advocates of this system see this as one of its advantages. A party with less than 40% of the popular vote can often win an outright majority of the seats. (For instance, in the 2005 UK General Election, the governing Labour party won by a majority of 66 seats in the House of Commons with only 35.2% of the popular vote.) If support for some parties is regionally concentrated, however, then Duverger's law applies separately to each region, and so it is quite possible for no party to be sufficiently dominant in each region so as to receive a majority of the seats. This was the situation in Canada in the 2004, 2006, and 2008 federal elections, with no party obtaining a majority due in part to the dominance of the Bloc Québécois in the province of Quebec.
   In the United States, the modern Democratic Party and Republican Party both have weak party discipline, but that varies somewhat between states. That is aptly illustrated by the vote on the federal Justice Against Sponsors of Terrorism Act, in which the only senator to vote against overriding President Barack Obama's veto was the retiring Democratic minority leader Harry Reid.
   In democratic multi-party systems such as India, Pakistan, etc., there is no restriction on the number of parties allowed to be in operation at any given time. Under these types of systems, people are free to participate in the political process both through elections and by forming their own political parties as they please.
  
  Examples of multi-party systems are:
  
  Section::::Political parties.:Single party systems.
  
  In single-party systems, one political party exercises control over the government. Unlike under other systems, single-party systems do not necessarily extend democratic privileges to the citizens. This means that citizens have little say regarding political subjects.
   A second reason is to gain power and influence. The incumbent may be a member of the minority party in a legislature and would like to gain the advantages of being in the majority party, such as the potential to chair a committee. A disaffected incumbent who might not hold a leadership position or feels ignored or mistreated by the majority party might join the minority party with the expectation of holding a leadership position in the minority party and if currently elected, having the complete support of the minority party for re-election, who would certainly want to have more elected officials in their ranks.
   French political scientist Maurice Duverger drew a distinction between "cadre" parties and "mass" parties. Cadre parties were political elites that were concerned with contesting elections and restricted the influence of outsiders, who were only required to assist in election campaigns. Mass parties tried to recruit new members who were a source of party income and were often expected to spread party ideology as well as assist in elections. Socialist parties are examples of mass parties, while the Conservative Party in the UK and the German Christian Democratic Union in Germany are examples of hybrid parties. In the United States, where both major parties were cadre parties, the introduction of primaries and other reforms has transformed them so that power is held by activists who compete over influence and nomination of candidates.
   In countries such as New Zealand, which use the mixed member proportionality system of voting, party discipline tends to be high. That is especially true for list MPs, who do not represent an electorate. If they do not vote the party line, they risk losing their seat.
  
  Section::::Weak party discipline.
  
  Weak party discipline is usually more frequent in parties of notables and elite parties than in populist parties. The centrist Radical-Socialist Party and the right-wing parties during the French Third Republic (1871–1940) all had no party discipline.
   Section::::Size Principle and Minimal Size Coalitions.
   Section::::Partisan style.:Bi-party systems.
  
  Two-party systems are states such as Honduras, Jamaica, Malta, Ghana and the United States in which there are two political parties dominant to such an extent that electoral success under the banner of any other party is almost impossible. One right wing coalition party and one left wing coalition party is the most common ideological breakdown in such a system but in two-party states political parties are traditionally catch all parties which are ideologically broad and inclusive.
   In practice, most countries with plurality voting have more than two parties. While the United States is very much a two-party system, the United Kingdom, Canada and India have consistently had multiparty parliaments. Eric Dickson and Ken Scheve argue that there is a counter force to Duverger's law, that on the national level a plurality system encourages two parties, but in the individual constituencies supermajorities will lead to the vote fracturing. Steven R. Reed has shown Duverger's law to work in Japan and Italy.
  
  Section::::Mechanism.
   Coalitions have burden-sharing effects and can increase the discursive leverage of its members
  
  Secondly small states can also use shaping strategies. Shaping strategies can include either legal, moral or normative argumentation applied in different negotiation settings. Framing and reframing is for example important for small states if there is a high number of delegations participating in the negotiations.
  
  These strategies help small states compete, but they are not always enough for them to compete successfully.
  
presuppositions: India and the U.K. have more than two major political parties. Small political parties in the UK and India are influential because they help form coalitions.
corrections: India and the U.K have only two major political parties. India and the UK are dominated by two parties, the other parties are too small and inconsequential.
raw_presuppositions: India and the U.K. have more than two major political parties. Small political parties in the UK and India are influential because they help form coalitions.
raw_corrections: India and the U.K have only two major political parties. India and the UK are dominated by two parties, the other parties are too small and inconsequential.