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Paradox of voting

Paradox of voting is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Paradox of voting rather than just read about it. In short: The paradox of voting, also called Downs' paradox, is that for a rational and egoistic voter (Homo economicus), the costs of voting will normally exceed the expected benefits. Because the chance of exercising the pivotal vote is minuscule compared to any realistic estimate of the private individual benefits of the different possible outcomes, the expected benefits of voting are less than the costs.

Paradox of voting — main illustration
Paradox of voting — illustration

Key takeaways

  • Paradox of voting belongs to science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Paradox of voting to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Paradox of voting from memory before moving on to harder problems.

Reference excerpt

The paradox of voting, also called Downs' paradox, is that for a rational and egoistic voter (Homo economicus), the costs of voting will normally exceed the expected benefits. Because the chance of exercising the pivotal vote is minuscule compared to any realistic estimate of the private individual benefits of the different possible outcomes, the expected benefits of voting are less than the costs. Responses to the paradox have included the view that voters vote to express their preference for a candidate rather than affect the outcome of the election, that voters exercise some degree of altruism, or that the paradox ignores the collateral benefits associated with voting besides the resulting electoral outcome.

History of scholarship The issue was noted by Nicolas de Condorcet in 1793 when he stated, "In single-stage elections, where there are a great many voters, each voter's influence is very small. It is therefore possible that the citizens will not be sufficiently interested [to vote]" and "... we know that this interest [which voters have in an election] must decrease with each individual's [i.e. voter's] influence on the election and as the number of voters increases." In 1821, Hegel made a similar observation in his Elements of the Philosophy of Right: "As for popular suffrage, it may be further remarked that especially in large states it leads inevitably to electoral indifference, since the casting of a single vote is of no significance where there is a multitude of electors." This problem in modern public choice theory was analysed by Anthony Downs in 1957. In a rational voter model the expected utility of voting U can be described as:

U = B ⋅ p − C {\displaystyle U=B\cdot p-C} , where B {\displaystyle B} is the benefit of a pivotal vote, p {\displaystyle p} is the probability of a pivotal vote and C {\displaystyle C} is the cost of voting.

Support of the rational voter model Predictions of the rational voter model on voter turnout dependency on total number of voters, competitiveness of elections, underdog status and cost of voting have been confirmed in a 2007 laboratory study. A stochastic element of voter turnout dependency on expected utility was found in the laboratory study.

Effect of polls

A 2020 study found the anticipated competitiveness of elections based on polls resulted in a causal increase of voter turnout.

Modifications of the rational voter model

Bounded rationality Bounded rationality with Quantal response equilibrium was found to be a better fit of observations in a 2007 laboratory study compared to a Nash equilibrium. The Logit Quantal response equilibrium predicted a 17% voter turnout for elections with a large number of voters without additional altruistic or civic duty terms.

Altruism theory of voting The altruism theory of voting assumes that voters are rational but not fully egoistic. In this view voters have some degree of altruism to voters of the same party. The altruistic utility increases with the large number of voters of the same party, which can explain the rationality of voting despite only a small chance of individually affecting the outcome.

Civic duty Voter turnout was found to increase with civic duty. Civic duty can be represented in the rational voter model as an additional benefit to voting independent of casting a pivotal vote. Voting and engaging in political discourse may increase the voter's political knowledge and community awareness, both of which may contribute to a general sense of civic duty. "I Voted" stickers and slogans such as "If you don’t vote, you can’t complain!" are connected to civic duty and citizenship models.

Other benefits Geoffrey Brennan and Loren Lomasky suggest that voters derive "expressive" benefits from supporting particular candidates – analogous to cheering on a sports team – rather than voting in hopes of achieving the political outcomes they prefer. This implies that the rational behavior of voters includes the instrumental as opposed to only the intrinsic value they derive from their vote. The magnitudes of electoral wins and losses are very closely watched by politicians, their aides, pundits and voters, because they indicate the strength of support for candidates, and tend to be viewed as an inherently more accurate measure of such than mere opinion polls (which have to rely on imperfect sampling).

See also

References

Illustrations

Paradox of voting: A crowd of voters queuing at a polling station in Caracas
A crowd of voters queuing at a polling station in Caracas
Paradox of voting illustration

Worked examples

Example 1 — a first encounter with Paradox of voting

Start with the simplest possible case. Write down what Paradox of voting claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Paradox of voting before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Paradox of voting ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Paradox of voting

In research
Paradox of voting appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Paradox of voting in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Paradox of voting is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1957 introductions, Decision-making paradoxes, Elections, so understanding it makes those chapters shorter.
In everyday life
Look for Paradox of voting outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.
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How to study Paradox of voting in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Paradox of voting means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Paradox of voting out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Paradox of voting in simple terms?

The paradox of voting, also called Downs' paradox, is that for a rational and egoistic voter (Homo economicus), the costs of voting will normally exceed the expected benefits. Because the chance of exercising the pivotal vote is minuscule compared to any realistic estimate of the private individual…

Why does Paradox of voting matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Paradox of voting?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Paradox of voting.

Tags

  • 1957 introductions
  • Decision-making paradoxes
  • Elections
  • Public choice theory
  • Voting theory

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