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What is the First Past the Post Voting System
The first past the post voting system is an electoral system in which the candidate who receives the most votes wins. Described this way, it sounds simple. And, indeed, it is. But it is neither inevitable nor obvious, and it carries with it significant implications for how a political system will function.
How the First Past the Post Voting System Works
The system is straightforward: the candidate with the most votes wins. This is the outcome regardless of whether or not the top vote getter has secured a majority. The winner could have won 34%-33%-32% in a three-way race. Or 26%-25%-25%-24% in a four way race. Or with an even smaller percentage of the total vote in an even larger field. All that matters is getting one more vote than the next leading vote getter.
The first past the post voting system is often associated with single-member legislative districts, such as in the United States House of Representatives or the British House of Commons. Under such a system, the top vote getter in the district’s election represents the district in the legislature.
Alternatives to First Past the Post
There are several alternatives to the first past the post voting system. One familiar alternative is multi-round voting, which is employed in some United States states for gubernatorial elections and several direct-election presidential systems. Under this approach, if no candidate wins a majority of the votes cast in an initial round, then a runoff is held between the top two vote getters. The “one on one” runoff guarantees that one candidate will receive a majority.
Another important alternative is the possibility of proportional party list voting. This system, employed in several continental European countries, eschews single member districts. Instead, voters vote for a party as opposed to a local candidate. Each party receiving a certain threshold percentage of votes – say, 5% -- wins a proportional number of seats in the legislature, proportionate to the percentage of votes received.
Another less familiar alternative is instant runoff voting, sometimes called IRV. Under the instant runoff system, voters rank candidates by preference. Thus, voters are able to “vote” for multiple candidates, under some models, even for all of the candidates that appear on the ballot. The least successful candidate is eliminated; all of that candidate’s “number one” votes go to the “number two” choice on each ballot in which he or she ranked first. And so on, and so forth. The result is just what the name suggests. The system simulates the a series of “voting rounds,” with even more iterations than the more familiar preliminary round-runoff system. Yet it does so all at once – in fact, with a single round of counting and computation.
The First-Past-the-Post System and Duverger’s Law
There is robust literature, historical experience, and theoretical modeling to suggest that a combination of the first past the post system and single-member legislative districts leads to a two-party system. This is known as Duverger’s Law. The short version of this well-developed theory is that , when the single highest vote getter wins, any faction outside of the top two has an incentive to join with one of the top two, since the third-place finisher (or lower) is shut out of power, and lacks the leverage over the top finisher that it might enjoy if the top finisher needed a majority in order to take office.