Journal of the History of Philosophy

In this exhaustively researched and thoughtful study of Leibniz’s neglected theological writings, Maria Rosa Antognazza presents a strong case that Leibniz held original and highly developed views on the relation between faith and reason, the theology of the Trinity, and the nature of Christ. Furthermore, she argues convincingly that Leibniz’s views were consistently maintained throughout his life and “coexist comfortably” with his distinctive metaphysics; “perhaps,” she suggests in the introduction, Leibniz’s metaphysics and theology are even “reinforcing one another” (xx). In fact, her book proves this suggestion correct, revealing the importance of Leibniz’s theology to the understanding of his metaphysics.

The book is structured into four parts: “Early Writings 1663–1671”; “Fragments of a System 1672–1692”; “English Trinitarian Polemics 1693–1705”; and “The Last Years 1706–1716.” Leibniz argues for three major theological positions. On the relation of faith and reason, he contends that the authority of scripture and theological tradition give the Christian mysteries a presumption of truth. The proper role of reason in theological matters is (i) to distinguish authentic revelations from false ones, (ii) to provide some understanding of the meaning of revealed truths (although perfect understanding is impossible), and (iii) to show that no contradiction is inherent or implied by the mysteries (xix, 17, 48–63, 69). On the Trinity, Leibniz distinguishes “relative” from “absolute” substances and argues that God consists of one absolute substance, but three relative substances (xxiii, 29, 45–47, 81, 103, 107–09, 153–58). Finally, on the Incarnation, Leibniz argues that the mind-body relation serves as an (imperfect) model for understanding the nature of Christ (39–41, 84–88, 129).

One of the best features of this book is the way in which the author explores the theological context of Leibniz’s writings. Many of the theological controversies that were important to seventeenth- and eighteenth-century philosophers are not well understood today: e.g., Andreas Wissowatius’s arguments against the coherence of the doctrines of the Trinity and the Incarnation (22–30); William Sherlock’s argument that minds—and so the persons of the Trinity—are individuated by self-consciousness (94–100); William Freke’s argument that the second and third persons of the Trinity are angels (111–12); and John Toland’s arguments, based partly on Lockean epistemology, that we should reject all religious mysteries because we should only believe what we can fully understand (120–30). Antognazza’s book provides succinct summaries of all of these, as well as a clear analysis of the replies they received. Like most seventeenth-century philosophers, Leibniz was careful not to commit himself inadvertently to heretical positions on the nature of substance, persons, relations, knowledge, etc., by accepting the premises of any these arguments. Thus, understanding them tends to shed light on the obscure aspects of Leibniz’s own philosophical system.

For example, in his attempt to resolve the dispute between Locke and Stillingfleet on the theological implications of Locke’s theory of substance, Leibniz clarifies his own views on the nature of “clear and distinct ideas.” He writes, “I call an idea clear when it suffices to recognize a thing . . . but I call an idea distinct when . . . I have a definition of it. . . . I believe that one has a clear idea, but not a distinct idea, of substance” (124). We have a clear idea of substances simply because we can feel that we ourselves are substances. Another example concerns Leibniz’s rejection of John Toland’s theology. Leibniz’s argument against Toland led him to modify his views on pre-established harmony (understood in this context as a solution to the mind-body problem). He follows tradition in claiming that the relation [End Page 145] between mind and body in human beings can serve as a model for understanding how Christ’s two natures, divine and human, could be united in one person. In...