Welfare economics

Welfare economics studies how resource allocations affect social well-being and how institutions or policies might improve it.

Pareto efficiency: An allocation is Pareto efficient if no feasible change can improve someone’s welfare without worsening someone else’s. It supplies a central, deliberately limited test of whether an allocation leaves gains unrealized.
First welfare theorem: Under standard assumptions, every competitive equilibrium is Pareto efficient. It explains why decentralized markets can achieve efficiency without central allocation.
Utilitarianism: An ethical theory that judges outcomes by the total well-being they produce. Utilitarian welfare functions aggregate well-being by summing individual utilities.
Vilfredo Pareto: An Italian economist and sociologist whose work shaped modern analysis of choice, efficiency, and distribution. His efficiency criterion became a foundational tool for welfare analysis.
Pigouvian tax: A tax set to reflect the marginal external cost of an activity. It can align private incentives with social costs when an externality is measurable.
Social welfare function: A rule that ranks social states by aggregating individual utilities or other measures of well-being. It makes explicit how individual outcomes are combined into a judgment about society.
Second welfare theorem: Under standard assumptions, any Pareto-efficient allocation can be supported as a competitive equilibrium after suitable redistribution. It separates efficiency from distribution by assigning redistribution to transfers before market exchange.
Rawlsian justice: A theory of justice that evaluates social institutions by principles chosen behind a veil of ignorance, including priority for the least advantaged. Its distributional priority can favor outcomes that do not maximize total utility.
Arthur Cecil Pigou: A British economist who developed early welfare economics and analyzed externalities and corrective taxes. His account of private and social costs helped frame policies for market failures.
Optimal taxation: The design of taxes to meet public goals while accounting for behavioral responses and social welfare. Tax policy makes the trade-off between redistribution and efficiency concrete.

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