We often hear that we live in a world where power and wealth are increasingly decentralised. The world is indeed changing, in some cases rapidly, as prior chapters in this book have documented. Despite this, there has been one constant since the end of the Second World War – the United States of America (US) has been the dominant military and economic power in the world and the manager of global security. The phrase ‘Pax Americana’ can therefore be used to describe an era without major war post-1945, overseen by the stabilising force and military might of the United States. IR calls actors that are noticeably above others in military and economic terms ‘hegemons’. While there have certainly been regional hegemons in the past, there has never been a global hegemon in known history – until now.
Today, the bulk of the citizens of earth would surely be able to identify the sitting American president by name, or at least recognise their face. This cannot be said for any other leader. Many debates in International Relations circle around the question of whether such a situation is desirable or sustainable. In order to address these debates, it is important to assess how dominant the United States is and whether the situation is likely to continue. As we ponder this we must also understand that a debate is underway not just internationally but also within American society over whether it should continue to play a global role. This chapter explores such questions in a direct and sometimes provocative way: the eventual answers, whatever they may be, will determine the next era of international relations. We should therefore not shy away from pondering the implications of a world beyond Pax Americana.