What's in a concept? Global public goods, international law, and legitimacy

Although the terminology of global public goods may be new to international law scholarship, many of the principal features and implications of global public goods are familiar: global public goods are externalities writ large; they create incentives to free ride; and in many cases, they require international governance to provide. Nevertheless, the global public goods literature has been valuable in highlighting that global public goods come in different types, with different 'production technologies'. Some depend on the aggregate effort of the entire group, while others depend on a 'single best effort' or on the 'weakest link'. These different types of global public goods raise different governance issues and hence different challenges for international law.