Why Democracy Is Mathematically Impossible

The Nugget

  • Democracy is mathematically impossible because no ranked voting system can satisfy all fair voting criteria simultaneously, a result known as Arrow's Impossibility Theorem.
  • Alternative voting methods like approval voting may provide better approximations but require further real-world testing.

Make it stick

  • 💡 First past the post results in majority power often not reflecting the majority vote.
  • 🔄 Condorcet Paradox: Preference loops where no clear winner emerges (e.g., A > B > C > A).
  • 🏴‍☠️ Arrow's Impossibility Theorem: It’s impossible to design a ranked voting system satisfying all fairness criteria with three or more candidates.
  • 👍 Approval voting: Voters approve of multiple candidates, potentially reducing negative campaigning and the spoiler effect.

Key insights

Problems with First past the post

  • Majority doesn’t rule: Often, parties with minority votes control the government.
  • Spoiler Effect: Minor candidates can skew results, leading to less-preferred outcomes.
  • Strategic voting: Encourages voting for more popular candidates instead of personal preference.

Alternatives to First past the post

  • Ordinal voting systems: Including instant runoff and preferential voting, which still have inherent flaws like the non-monotonicity problem.
  • Condorcet method: Each candidate faces all others in head-to-head matchups, but can result in paradoxes.

Arrow's Impossibility Theorem

  • Conditions: Unanimity, no dictator, unrestricted domain, transitivity, and independence of irrelevant alternatives.
  • Conclusion: No ranked-choice voting system can meet all these criteria simultaneously.

Approval Voting as a Solution

  • Simplicity: Voters simply approve all candidates they find acceptable.
  • Advantages: Increases voter turnout, reduces negative campaigning, and prevents the spoiler effect.
  • Historical and current use: Historically used by the Vatican and currently by the United Nations.

Key quotes

  • "Arrow’s impossibility theorem seems to say so**: If there are three or more candidates to choose from, there is no ranked Choice method to rationally aggregate voter preferences."
  • "The pivotal voter determines society’s preferences, essentially making them a dictator."
  • "Approval voting is not new. It was used by priests in the Vatican to elect the pope between 1294 and 1621."
  • "Just because things aren’t perfect doesn’t mean we shouldn’t try. Being politically engaged is important; it might be one of the few ways we can make a real difference in the world."
  • "Democracy is the worst form of government, except for all the other forms that have been tried." - Winston Churchill
This summary contains AI-generated information and may have important inaccuracies or omissions.