In the fifth century bishops had brought problems to the apostolic see, which replied by laying down what was lawful and unlawful (leaving the bishops to do what they wanted with these responses). Shortly after the end of the empire in the West, the first decretal age comes to an end and a new phase begins: one of synthesis and compilation. This meant deciding what to leave out and what to include. Two collections, the Frisingensis prima and the Quesnelliana, include debate on the humanity and divinity of Christ, alongside the papal responses. The Dionysiana, however, leaves out these themes, which are in any case absent from the decretals of Siricius and Innocent I. Christological themes are absent also from letters of Leo I selected by Dionysius and from the ‘hold-all’ decretal Necessaria rerum dispositione of Gelasius I, which draws together in a quasi-synthesis the principal issues addressed in the first century of papal jurisprudence. Gelasius’s summative decretal and the Dionysiana anticipate the boundary that would separate canon law from what would be called theology, while the Frisingensis prima and Quesnelliana anticipate collections which recognize no such boundary.

That papal responses about Pelagianism belong to a specifically legal domain is a secondary conclusion of the chapter. The primary conclusion can be integrated with a central argument about the origins of the first papal jurisprudence, viz., that it was demand-driven, and that the demand was driven by uncertainty. We should not be surprised at uncertainty in late Antiquity about grace and free will when modern scholars write in such different terms about Augustine. Many modern people prefer Pelagius, but Augustine’s understanding of grace won the assent of intellectuals like Gottschalk in the ninth century, Bradwardine in the fourteenth, and Luther and Calvin in the sixteenth, and it continued to have adherents within Catholicism, even after the Council of Trent. Self-evident the solution to the argument was not. Given the violently opposed views, in this apparently purely Western controversy, it is not surprising that the apostolic see was asked for a response. Baffled by the paradox of divine omnipotence and human free will, it did what it would do in subsequent centuries: step back from acceptance of Augustine’s late views, without breathing a word of criticism against him.

Influence of the dualist ‘Encratite’ tradition helps account for the pessimistic colouring of Augustine’s view of human nature, but this is far from being the whole story, in which a turning point was his attempt to explain what it could mean to say that God hated Esau. The sacred books which both Augustine and Pelagius accepted without question could bear either of their probably honest interpretations of grace. Even modern scholars can react strongly in opposite directions to this fifth-century controversy, on a spectrum from barely concealed dislike of Augustine’s idea of grace to apparently heartfelt eloquence in presenting it. While twenty-first-century society is comfortable with pluralism, at least on these topics, fifth-century Christianity was not. Contradictory certainties must have generated both uncertainty and unease among those not committed to either side.

In Liberty before Liberalism, Quentin Skinner formulated what has turned out to be one of the most generative distinctions in recent political theory. Late medieval lawyers and Renaissance humanists, he explained, developed a 'neo-Roman' theory of freedom, according to which persons are free only if they are not dependent on the will of another person. It was this theory, for Skinner, that Thomas Hobbes momentously dislodged by redefining freedom as the absence of interference – thus paving the way for the emergence of 'liberalism'. This chapter questions the degree to which the liberal tradition did in fact assimilate the Hobbesian theory of liberty. It suggests that Kantian liberals accepted the neo-Roman account of political liberty, while simultaneously insisting that, in the realm of metaphysics, being one’s own master was insufficient to render a person free. I claim that we can only understand this fact about liberalism if we recognize Kant’s place in the early-modern Pelagian tradition. I also explain why this genealogy proved uniquely problematic for Kant’s most famous twentieth-century disciple, John Rawls.

Chapter 8 responds to potential objections. Against the objection that my proposal is a recrudescence of “two-tier Thomism,” I argue that it is deeply congruous with Henri de Lubac’s view that nature innately desires grace. The second objection is that my view implies that a state of pure nature is impossible. I argue that it is in fact compatible with a wide variety of views of divine providence. Further objections are raised that focus on the nature of sanctifying grace, the ecumenical potential of a Thomist perspective, and Pelagianism. My proposal, I suggest, is compatible with a wide variety of views of justification, and it is not “Pelagian” in any meaningful sense.

Chapter 25 considers the 1547 Tridentine Decree on Justification. This document is widely regarded as one of the most significant statements on the doctrine of justification. It set out a full exposition of the Catholic position, rather than simply rejecting opinions regarded as unacceptable. The Council saw its task as ‘expounding to all the faithful of Christ the true and sound doctrine relating to justification’, not simply identifying what they considered to be the errors of Protestantism. This chapter consists of four sections. The first considers the Decree’s teaching on the first stage of justification, which includes a strongly transformist concept of justification, and a rejection of any idea that justification can be said to be merited. It also firmly links justification with the sacrament of baptism. The second considers its teaching on the second stage of justification, dealing with the way in which believers increase in righteousness. The third deals with the restoration of justification through the sacrament of penance. Finally, the canons of the decree, dealing with views that the Council regarded as unacceptable, are noted and their significance assessed.

This important chapter focusses on the development and core characteristics of Augustine of Hippo’s views on justification, which were one of the most significant factors in shaping the western theological tradition’s reflections on this theme in the Middle Ages and during the Reformation debates of the sixteenth century. The chapter opens by considering the overall trajectory of Augustine’s views on grace, and how Paul’s concept of justification fits into this development. Augustine consistently interprets the Pauline concept of ‘justification’ to mean ‘a making righteous’, and does not develop a reputational or forensic approach to the concept. Augustine’s concept of the ‘righteousness of God is considered in some detail, with particular attention being paid to the manner in which Augustine distinguishes this theological use of the concept from its secular counterparts – as seen, for example, in the works of Cicero. The chapter also considers the ways in which Augustine’s approach to justification was affected by the Pelagian controversy, which tended to focus on the framework within which the concept of justification was set, rather than the notion of justification itself.

Tensions arising from the establishment of monasteries in Gaul by John Cassian get associated in a long decretal of Celestine I with Cassian’s mild but firm critique of Augustine of Hippo’s views on grace and free will. These topics are the only core theological subjects discussed at length in the Dionysiana and Quesnelliana collections: the latter has three fascinating letters of Innocent I to African bishops, apparently endorsing their hard-line views on grace and (corrupted) nature, but in fact significantly silent on key points, stoppping short of some hard-line Augustinian positions.

Rather than providing a detailed survey of recent research (since this is available elsewhere), the chapter concentrates on the key contributions to the field of Erich Caspar, Charles Pietri, Geoffrey Dunn, and two historians influenced by Michel Foucault: Kristina Sessa and George Demacopoulos.