This paper carries out a literature review on the use of the Public Good Theory to explain global phenomenon as international treaties, alliances and environmental threats. It gives explanation of why some international agreements fail and why some other do not. Afterward it is applied the theory to real world case studies as NATO, the Montreal Protocol and the Kyoto Protocol. The paper also presents the main existing empirical evidences in favour of the exploitation hypothesis of the smaller European allies on the USA and its political consequences: from the Trumps victory to the likelihood of a EU Army.
The whole paper is self-contained, and its understanding is made accessible to a broad public thanks to a generous introduction of all the major concepts.