11.1 Voting Methods
3 min read•june 18, 2024
Voting systems shape how we choose leaders and make decisions. From simple to complex ranked-choice methods, each system has its own way of translating into outcomes.
No perfect voting system exists, as each has flaws and trade-offs. Understanding these systems helps us grasp the complexities of democracy and the challenges in fairly representing diverse viewpoints in decision-making processes.
Voting Systems
Voting systems comparison
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- Plurality voting involves each voter selecting one candidate and the candidate with the most votes wins without requiring a (can lead to a winner not preferred by the majority)
- ###ranked-choice_voting_()_0### has voters rank candidates in order of preference, eliminating the candidate with the fewest votes and redistributing their ballots until a candidate receives a majority (ensures the winner has majority support)
- assigns points based on the ranking of candidates (3 points for 1st choice, 2 for 2nd, 1 for 3rd) and the candidate with the most points wins (considers the relative preference of each candidate)
- () compares each candidate head-to-head against every other candidate and the winner is the candidate who defeats all others in pairwise comparisons (may not always produce a clear winner due to the )
Application of voting methods
- Plurality method counts the total number of first-choice votes for each candidate and the candidate with the most first-choice votes wins
- (RCV) follows these steps:
- Count the first-choice votes for each candidate
- If no candidate has a majority, eliminate the candidate with the fewest votes
- Redistribute the eliminated candidate's ballots to the next choice on each ballot
- Repeat the process until a candidate receives a majority
- Borda count assigns points to each candidate based on their ranking on each ballot, sums the points for each candidate across all ballots, and the candidate with the most points wins
- Pairwise comparison (Condorcet method) compares each candidate against every other candidate in head-to-head matchups, determines the winner of each pairwise comparison based on majority preference, and the candidate who defeats all others in pairwise comparisons is the winner
Flaws in voting systems
- Plurality voting is susceptible to the "" where a third-party candidate splits the vote, can lead to a winner who is not preferred by the majority, and encourages (voting for a less preferred but more likely to win candidate)
- Ranked-choice voting (RCV) may not always produce a winner who is the first choice of the majority and can be more complex for voters to understand and for election officials to implement
- Borda count is vulnerable to strategic voting by ranking a less-preferred candidate higher to lower the score of a strong opponent and may not always reflect the majority preference in head-to-head comparisons
- Pairwise comparison (Condorcet method) can result in a cyclical preference (A beats B, B beats C, C beats A), known as the Condorcet paradox, where there is no clear winner
- states that no voting system can satisfy all desirable criteria for fairness and consistency, highlighting the inherent limitations and trade-offs in designing voting systems
Electoral Systems and Representation
- is a fundamental principle in many voting systems, where decisions are made based on the preferences of more than half of the voters
- aims to allocate seats in a legislative body in proportion to the overall voter preferences, ensuring diverse viewpoints are represented
- Various (such as first-past-the-post or mixed-member proportional) implement different approaches to translating voter preferences into political representation
- are used to evaluate voting methods, including criteria like monotonicity, independence of irrelevant alternatives, and Condorcet consistency
Key Terms to Review (27)
Approval voting ballot: An approval voting ballot allows voters to select (approve) any number of candidates rather than just one. The candidate with the highest number of approvals wins the election.
Approval voting system: An approval voting system allows voters to select (approve) any number of candidates they choose. The candidate with the most approvals wins.
Arrow's Impossibility Theorem: Arrow's Impossibility Theorem states that no voting system can perfectly translate individual preferences into a collective decision while meeting a specific set of fairness criteria. This theorem highlights the challenges of creating a fair voting method that respects all voters' preferences, as it reveals inherent limitations in aggregating these preferences into a single outcome.
Borda count: The Borda count is a ranked voting method used to determine the winner of an election by assigning points based on voters' preferences. In this method, voters rank candidates in order of preference, and points are allocated to each candidate according to their ranking on each ballot. This technique aims to reflect the overall preferences of the electorate and is often discussed in relation to fairness in voting systems, as it seeks to minimize the impact of tactical voting and provide a more representative outcome.
Condorcet method: The Condorcet method is a voting system used to determine the most preferred candidate in an election by comparing each candidate against every other candidate in a series of head-to-head contests. This method identifies a Condorcet winner, who is the candidate that would win against all other candidates if elections were held in pairs. It highlights the importance of majority preference and provides a systematic approach to evaluate the preferences of voters, ensuring a fair outcome.
Condorcet paradox: The Condorcet paradox occurs in voting systems when collective preferences among voters create cycles, meaning that no candidate is the clear winner based on pairwise comparisons. This highlights a fundamental issue in voting methods, as it illustrates how individuals' preferences can lead to contradictory group preferences, complicating the determination of a fair winner. Understanding this paradox is essential for analyzing the effectiveness and fairness of various voting methods, as it showcases the potential inconsistencies that can arise in election outcomes.
Electoral systems: Electoral systems are the rules and methods used to determine how votes are cast, counted, and translated into seats in a legislature or other decision-making bodies. These systems play a crucial role in shaping political representation and influencing the behavior of voters and candidates. Different electoral systems can lead to vastly different political outcomes, affecting party dynamics, voter engagement, and the overall health of a democracy.
Fairness criteria: Fairness criteria are principles used to evaluate voting methods and ensure that the outcomes of elections reflect equitable treatment of all voters and candidates. These criteria help in assessing whether a voting system is just and representative, focusing on minimizing potential biases and ensuring that each voter’s preferences are considered fairly in the decision-making process.
Hare Method: The Hare Method is a voting system used to allocate seats in proportional representation. It involves a process of elimination, where the candidate with the fewest votes is eliminated and their votes are redistributed until a winner is determined.
Instant runoff voting (IRV): Instant runoff voting (IRV) is a voting method where voters rank candidates in order of preference. If no candidate receives a majority, the candidate with the fewest votes is eliminated and their votes are redistributed until one candidate has a majority.
Majority: Majority is the condition in which more than half of the votes or elements in a set are in favor of a specific option or candidate. It is commonly used to determine outcomes in voting systems and decision-making processes.
Majority rule: Majority rule is a decision-making principle where the option that receives more than half of the votes is selected as the outcome. This concept is fundamental in various voting systems, ensuring that the preferences of the greater number of participants take precedence over those of the minority. It plays a crucial role in promoting democratic processes by allowing collective decision-making and reflecting the will of the majority.
Pairwise comparison: Pairwise comparison is a method used to evaluate and rank alternatives by comparing them directly against one another in pairs. This technique helps to identify preferences and determine which options are more favorable based on individual or collective preferences. By systematically comparing each option with every other option, it creates a clear picture of the relative standings of the alternatives.
Plurality voting: Plurality voting is a voting method in which the candidate receiving the most votes wins, regardless of whether they achieve a majority (more than 50% of the votes). This system is widely used in various elections, including political races, as it is straightforward and easy to understand. However, plurality voting can lead to scenarios where a candidate wins without broad support, which raises important questions about the fairness and representation of this method.
Preference ranking: Preference ranking is an ordered list in which voters rank choices based on their personal preferences. It is commonly used in voting methods to determine a collective decision from individual rankings.
Proportional Representation: Proportional representation is an electoral system that seeks to allocate seats in a legislature in proportion to the number of votes each party or candidate receives. This approach aims to create a fairer representation of diverse political views, allowing for a more accurate reflection of the electorate's preferences in decision-making processes.
Ranked ballot: A ranked ballot allows voters to rank candidates in order of preference rather than selecting just one. This method helps ensure that the winner has broad support among voters.
Ranked voting: Ranked voting is a voting method in which voters rank candidates in order of preference rather than choosing just one. The rankings are used to determine the winner through a process of elimination or points allocation.
Ranked-choice voting: Ranked-choice voting is an electoral system that allows voters to rank candidates in order of preference rather than selecting just one candidate. This method helps to ensure that the winning candidate has broad support, as it can take into account voters' second and third choices if their top choice does not receive enough votes to win. By allowing voters to express their preferences more fully, ranked-choice voting promotes a more inclusive and representative electoral process.
Ranked-choice voting (RCV): Ranked-choice voting (RCV) is an electoral system where voters rank candidates by preference on their ballots. If no candidate wins a majority, the candidate with the fewest votes is eliminated and their votes are redistributed until one candidate has a majority.
RCV: Ranked Choice Voting (RCV) is an electoral system where voters rank candidates in order of preference rather than selecting just one. This method allows voters to express their preferences more fully and can lead to more representative outcomes, as it ensures that elected candidates have broader support among the electorate. RCV can also help reduce negative campaigning and encourages more candidates to run, knowing they won't be limited to just first-choice votes.
Runoff election: A runoff election is a second round of voting conducted when no candidate achieves the required majority in the initial round. It ensures that the winning candidate has broad support from the electorate.
Spoiler: A spoiler is a candidate in an election who is unlikely to win but can affect the outcome by taking votes away from a major candidate. This can alter the final result, often leading to a less favored candidate winning.
Spoiler effect: The spoiler effect occurs in elections when a candidate who has little chance of winning siphons votes away from a more viable candidate, ultimately affecting the outcome of the election. This phenomenon highlights the intricacies of voting systems, as the presence of a third-party or independent candidate can alter the dynamics between major candidates, leading to unexpected results.
Strategic voting: Strategic voting occurs when voters choose a candidate not because they are their first choice, but to prevent an undesirable outcome, such as the election of a less favored candidate. This behavior highlights the complexities of voting methods, where voters may manipulate their votes to influence the overall election results, rather than purely expressing their preferences. It raises questions about the effectiveness and fairness of various voting systems.
Two-round system: A two-round system is a voting method used to elect a single winner where voters cast their vote for their preferred candidate in the first round, and if no candidate receives a majority, a second round is held between the top two candidates. This ensures that the elected candidate has broad support among voters.
Voter preferences: Voter preferences refer to the attitudes and choices of individuals regarding candidates, policies, or issues in an election. These preferences can significantly influence electoral outcomes and are often shaped by various factors such as personal beliefs, party affiliation, socioeconomic status, and social influences. Understanding voter preferences is crucial for analyzing how different voting methods may impact election results and representation.