A lifeboat built for sixty has fifty aboard and a hundred swimmers begging to get in

Ecologist Garrett Hardin proposed this metaphor in 1974 to argue about global aid and immigration: a lifeboat holding fifty people, with room for ten more, floats in water full of a hundred swimmers. Pulling everyone aboard sinks the boat and kills everyone; refusing anyone condemns swimmers to drown while the boat sails on with empty capacity. Hardin argued rich nations, like the boat, cannot responsibly take in everyone who wants in, a conclusion critics call a self-serving choice of metaphor.

— Garrett Hardin, Lifeboat Ethics: The Case Against Helping the Poor — Psychology Today, 1974