Mostlymajority

Mostlymajority is a term used in political science and social choice theory to describe a family of decision rules for aggregating preferences across multiple subpopulations or districts. The central idea is to determine an outcome not by the global majority of all voters alone, but by the majority status achieved in the largest number of subgroups. In this sense, mostlymajority emphasizes regional or subgroup majorities as a basis for overall choice.

Formally, consider a set of subgroups, each of which may express support for alternatives. For each alternative, count how many subgroups show a majority in its favor. The mostlymajority rule selects the alternative that is the majority in the greatest number of subgroups. If more than one alternative ties for the highest count, a tie-breaker rule is applied, such as choosing the option with the larger overall support, or using a random or predetermined secondary criterion.

Applications of mostlymajority appear in discussions of federations, multi-district referendums, or any setting where regional outcomes are aggregated to produce a national or aggregate decision. The rule is often contrasted with global majority rules (which require a majority across all voters) or with pure plurality methods, highlighting its emphasis on the distribution of majority support across subunits rather than a single aggregate tally.

Criticism centers on potential distortions of overall popular will, sensitivity to how subgroups are defined, and vulnerability to gerrymandering or boundary effects. Proponents argue that it better protects regional consent and reduces the influence of extreme results in small subgroups.

Related topics include social choice theory, federalism, multi-district representation, and alternative aggregation methods.