Chapter 2 undertakes to provide a critical narrative of the development and direction of international law as it was characterised by Catholic preoccupations from the Medieval and Early Modern era. Chapter 2 surveys the theological and philosophical contribution to the structure of premodern international law by Augustine, Thomas Aquinas, Francisco de Vitoria and Robert Bellarmine. They assisted the Catholic Church at crucial moments in its history and left an enduring legacy, which could broadly be described as a foundation for a Catholic cosmopolitan approach to international law. This process is highlighted and contrasted with the way early-modern international law was constructed. The structure of international law that emerged during the eventful sixteenth and seventeenth centuries led to Catholic political and legal thought becoming a minor key in the development of a secularised public international law in the nineteenth century. This distinctively different approach to sovereignty and international order provides an opportunity to examine the peripheral place of religion, particularly Catholicism, in the structure of nineteenth-century international law.

The period between the French Revolution and the mid-twentieth century was a period of significant upheaval for Catholicism and in its interpretation of its role in relationship to the growth of nationalism, human rights and international relations. Chapter 1 examines how the Church developed Catholic social and political thought through human rights ideas. Catholicism gradually responded to the emergence of rights-based language, which it initially rejected, and only later engaged in active participation. Section 1.2 appraises in what manner the Catholic Church had available a long cosmopolitan tradition of reflection on the natural law, and this tradition in particular became a resource to a changing political landscape. Section 1.3 appraises the Catholics resolution of the tensions in rights language through the development of the philosophy of Personalism, and a reassessment of democracy as a foundation of cosmopolitan political life. This chapter concludes in Section 1.4 by presenting where those ideas were reaffirmed in later papal declarations and encyclicals.

By the end of the nineteenth century Catholicism had become a peripheral player in the international arena. This would change in the twentieth century as Catholicism would re-emerge as a formative participant in the creation of the Human Rights movement. To examine this question, Chapter 3 seeks to comprehend in what manner Catholicism began moving from the periphery to the centre of international law. The narrative begins to distinguish how Catholicism began drawing upon its own understanding of the natural law and the formation of the state, and explores in what manner the Catholic Church would shape democratic constitutions and international law across Europe. The Catholic Church’s engagement with the construction of human rights became a cosmopolitan vehicle to participation in the international legal system, which mapped out in a number of ways. This chapter concludes by ascertaining how this latter engagement provided the Catholic Church with theoretical underpinnings to further shape the direction of human rights, in its negotiation and engagement with a globalised world. It reveals how Catholic cosmopolitanism was understood as the political form of sovereignty.

International law has a standard account of the nature of both international law and human rights. Hugh Thirlway states that ‘all subsystems or specialized fields of international law will operate on the basis that they derive their force from the established sources of Article 38 of the ICJ Statute’. Therefore, religion does not provide international law with an established source, and ‘in principle, the individual legal, political, or religious system of a State does not impinge on its acceptance of, and compliance with, general international law’. Further, Thirlway remarks, since ‘the waning of the influence of the teachings of the Catholic Church on moral and legal concepts, it has become possible for at least half a century to say that international law is now free from any religious input—that it is “laicized”’. The formal sources of international law, which are by in large viewed as a pragmatic agreements founded in a secular positivistic legal science developed since the nineteenth century, has had to engage again with religion in a manner that was unanticipated.

Sixteenth-century jurist, Thomas More, developed the distinction between a Christian utopia and the political autonomy of the state. Chapter 4 recognises religion’s role in contributing to cosmopolitan ethical principles to guide political power, without becoming a justification for a political theology of the state. Section 4.1 proceeds with More’s emphasis of a common humanism that brought accommodation between temporal and spiritual sovereignty. Section 4.2 ascertains in what manner the Second Vatican Council recognised that not alone freedom but the search for the truth is central to political democracy and an open public sphere. Catholic theorists recognise a prisca theologia or a semblance of the natural law, and thereby advance in what way the expression of the political form the state takes as a basis for a common cosmopolitan humanism. Section 4.3 details Maritain’s proposed model of Church and state, and delineates Maritain’s theory of secular democratic faith, as a bridging of Catholicism with liberal democracy and human rights. This chapter concludes by enquiring if a secular democratic faith in democracy and human rights is possible today.

Human rights would become instrumental in trying to resolve the tensions between religion and the modern state. Chapter 5 commences with the Irish Constitution, which illustrates how Catholic political thought would evolve as a cosmopolitan civil society project. The use of rights-based language within this Constitution was part of the trend to both restrain a newly forming nation state, while at the same time to acknowledge the limits of religion in such a new political polity. During the Cold War the Christian democratic parties consolidated and expanded European political and economic cooperation, and Section 5.2 of the chapter looks at how those who shaped that era began drawing human rights into the confrontation between Eastern and Western Europe by emphasising religious freedom. In Latin America, human rights became a distinctively different project, and Section 5.3 examines in what manner human rights was used against state authority and part of a programme of liberation and democratisation. In each of these many contexts, a cosmopolitan Catholicism presented the value of participating in the human rights project with varying degrees of success.

The toast to conscience indeed must precede the toast to the Pope because without conscience there would not be a papacy. All power that the papacy has is power of conscience.

Having evaluated the long trajectory and contested narrative of the relationship between cosmopolitan Catholicism and human rights, we can recognise that Catholicism remains influential in offering competing ideas about the modern state, and international relations. It retains its own distinctiveness and contributes by way of an alternate critical approach to international law. In the view of the Catholic Church, the ethical theory and development of the natural law is a contribution to international law, and its place is arrived at through dialogue about the nature of the relationship between faith and reason. Human rights exist not because they are a modern invention but because they are the practical realisation in law of a prolonged reflection on the just exercise of power.