Philipp Melanchthon has long stood in the shadow of his far more famous colleague Martin Luther. In the last thirty years, though, Melanchthon has gained new attention not only as a theologian but also as a humanist educational reformer and philosopher. Mads Langballe Jensen's book contributes to this broader understanding of Melanchthon by describing the evolution of the reformer's political philosophy from the 1520s through its mature expression at the time of the Schmalkaldic War (1546–1547). Against those who claim that Melanchthon's political thought was subordinate to his theology, Jensen argues that the Wittenberg reformer was an important contributor to German political thought, particularly by formulating an understanding of natural law that influenced discussions into the eighteenth century.

Jensen points out that existing work on Melanchthon's political thought is based largely on the reformer's theological writings. In contrast, he concentrates on Melanchthon's rhetorical and philosophical works, and especially his commentaries and textbooks on Aristotelian moral philosophy. Jensen asserts that Melanchthon's understanding of natural law developed in response to the political and religious conflicts of the time, and he locates an important turning point in the early 1530s.

Jensen begins his study with Melanchthon's approach to politics as set forth especially in two orations from the mid-1520s. These were humanist in form and more strongly influenced by Cicero than by Aristotle. They differed in content from contemporary humanist political thought, however, because of Melanchthon's Lutheran distinction between Law and Gospel and his understanding of the two realms of civic or political righteousness and divine righteousness. These features of the reformer's thought would remain constant throughout his life.

The next two chapters demonstrate the impact of Aristotle on Melanchthon's political thought. Chapter 2 describes the reformer's more considered reflection on politics as expressed in his commentaries on Aristotle's Politics and Nichomachean Ethics published between 1529 and 1535. These works present an understanding of natural law developed in opposition to the Ockhamist position, which Melanchthon probably learned while a student in Tübingen. The Wittenberger also addressed claims that rulers were subject to the consent of the governed made in pamphlets published during the 1525 Peasants’ War. In response, Melanchthon first expressed an understanding of political authority founded on natural law, which required the obedience of subjects, although it also set limits on the ruler's will.

The third chapter examines Melanchthon's textbooks on Aristotelian moral philosophy, first published in 1538 and successively revised and expanded up to his death in 1560. Jensen argues that Melanchthon's new emphasis in the 1530s on the magistrate's responsibility for protecting true religion led to a fundamental change in his theory of natural law as well. He now saw natural law as that part of divine law accessible to reason and identified with the Decalogue. This natural law was the subject of moral philosophy, which served as a guide to individual and civic conduct. It not only provided a standard for the political order and the ruler's conduct but also allowed subjects to resist tyrants.

The final chapter looks at the question of political resistance more closely. Jensen argues that Melanchthon countered Catholics who accused the Lutherans of political rebellion by justifying resistance on philosophical rather than religious or biblical grounds. His position presented an alternative to the more apocalyptic justifications for resistance developed by the Gnesio-Lutherans, and Jensen suggests that it was ultimately more influential than the better-known Magdeburg Confession (1550). The book's conclusion concisely summarizes the argument developed in these four chapters.

A book on the history of political theory could easily become bogged down in abstruse details, but Jensen has avoided such pitfalls. He begins each chapter by summarizing both German- and English-language research and then highlights his own contribution to the debate. To set Melanchthon's ideas in their broader context, he gives a short synopsis of political developments and discusses other writers who served as a foil to the Wittenberger's thought. Although he recognizes that Melanchthon developed his political philosophy in the course of his university lectures, Jensen says very little about Melanchthon's own teaching. More explicit discussion of these lectures would have been welcome, because the daily experience of teaching was surely as much an influence on the development of Melanchthon's thought as the larger political and religious conflicts.

This book does not fundamentally change our understanding of Melanchthon's political thought, but it does extend and deepen it by considering its philosophical rather than its theological expression. Melanchthon's particular combination of humanist practices and Lutheran ideas distinguished him from both groups. His fundamental separation of civic and divine righteousness also allowed for the development of political theory independent from the discipline of theology. A Humanist in Reformation Politics is well worth reading for anyone interested in the history of early modern political thought.