Samuelson's contribution to public goods theory

Paul Samuelson's key contribution to public goods theory was formally defining the characteristics that distinguish public goods from private ones. He explained that public goods are both non-excludable (you can't prevent anyone from using them) and non-rivalrous (one person's use doesn't reduce availability to others). His work highlighted why private markets often underprovide public goods, as individuals may free-ride, benefits without paying. This insight informed how governments might need to step in to fund and manage such goods—like clean air, national defense, or public broadcasting—to ensure they are available for everyone.