TL;DR: In this view, a Hobson's choice between anarchy and hierarchy is not necessary because an intermediary structure, here dubbed "negarchy" is also available as mentioned in this paper, which is a theory of security that is superior to realism because it addresses not only threats of war from other states but also the threat of despotism at home.
Abstract: A rediscovery of the long-forgotten republican version of liberal political theory has arresting implications for the theory and practice of international relations. Republican liberalism has a theory of security that is superior to realism, because it addresses not only threats of war from other states but also the threat of despotism at home. In this view, a Hobson's choice between anarchy and hierarchy is not necessary because an intermediary structure, here dubbed “negarchy,” is also available. The American Union from 1787 until 1861 is a historical example. This Philadelphian system was not a real state since, for example, the union did not enjoy a monopoly of legitimate violence. Yet neither was it a state system, since the American states lacked sufficient autonomy. While it shared some features with the Westphalian system such as balance of power, it differed fundamentally. Its origins owed something to particular conditions of time and place, and the American Civil War ended this system. Yet close analysis indicates that it may have surprising relevance for the future of contemporary issues such as the European Union and nuclear governance.
TL;DR: The Westphalian and the Philadelphian systems as discussed by the authors have been widely accepted as the core of realist international relations theory, and have been studied in the Western world since at least the Middle Ages.
Abstract: The Westphalian and the Philadelphian systems The relationship between forms of legitimate political authority and the capacities of coercive power has been at the center of the Western study of politics since the ancient Greeks began systematically investigating politics. At least since the Middle Ages, these debates have been about “sovereignty.” Because the modern European system has expanded globally over the last half millennium, students of international politics have focused on the Westphalian system of sovereign states as a paradigm so much that it seems inevitable and universal. The essentials of the Westphalian system, codified as the core of realist international relations theory, are widely accepted. Westphalian realists presume a dyadic conception of political order: hierarchy inside and anarchy outside. Thus sovereign authority has two faces, an inside and an outside. Inside the territorial units, the sovereign state monopolizes the violent power that creates a hierarchy of higher and lower authorities. To avoid ambiguity, a hierarchically structured unit should be called a “hier-state.” Outside and between states, authoritative governance is absent or fleeting. But interstate order exists, primarily because of two institutions and practices: mutual recognition of sovereignty and the balance of power. State sovereigns extend to one another the system of mutual recognition that creates a society of states, reflecting and embodying state supremacy, while moderating state power and anarchy. As Martin Wight, Hedley Bull, and others have noted, this European society of states existed in addition to the anarchical and balance-of-power system of states.