May's Theorem characterizes simple majority rule among methods for aggregating a group's two-option preferences into a single collective decision, showing that majority rule is the unique method satisfying four conditions: treating every voter equally, treating both options equally, responding positively to a swing in any voter's preference, and depending only on the votes actually cast. Named for Kenneth May, it is a foundational result of social choice theory giving an axiomatic justification for majority voting.
Facts
StatementMajority vote is the unique ranked social choice function between two candidates that satisfies Anonymity, Neutrality, Decisiveness, Positive response, and Ordinality. 2 Classification
Statement Form Connections
Has Statement Form
Entity-backed identity for the statement-form enum value this theorem already carries, resolved to a mathematics concept by an explicit value-to-entity map (phase 3 bucket conversion, docs\design_entity_backed_browse_buckets_20260928.md). The statement-form fact itself stays on the theorem unchanged.
Sources
1. Wikipedia: May's theorem
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In social choice theory, May's theorem, also called the general possibility theorem, says that majority vote is the unique ranked social choice function between two candidates that satisfies the following criteria: Anonymity: the decision rule treats each voter identically (one vote, one value).
2. May's theorem, Wikipedia
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majority vote is the unique ranked social choice function between two candidates that satisfies the following criteria: Anonymity, Neutrality, Decisiveness, Positive response, and Ordinality.
3. Wikidata: May's Theorem
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The theorem was first published by Kenneth May in 1952.
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