Journal of Analytic Theology, Vol. 6, August 2018
© 2018 Samuel Murray  •  © 2018 Journal of Analytic Theology

Irena Backus. Leibniz: Protestant Theologian. New York, NY: Oxford University Press, 2016. 336 pp. $78.00 (hbk).

Samuel Murray
Universidad de los Andes

In Leibniz: Protestant Theologian, Irena Backus aims to “show the coexistence of theology and philosophy in Leibniz and to see how the two come together” (1). Backus focuses on Leibniz’s theories of substance (chapters 1-2), freedom (chapters 3-5), and history (chapters 6-7). She argues that in these domains, Leibniz’s theological commitments influenced and shaped his philosophical theorizing.1

In the first two chapters, Backus argues that Leibniz’s theory of substance is an attempt to appropriate Calvin’s doctrine of real spiritual presence into a theory of the Eucharist. Leibniz’s theory of substances as entities with active and passive force is crucial to explaining the transformation of the real accidents of bread and wine into body and blood (207). In chapters 3-5, Backus claims that Leibniz’s account of hypothetical necessity explains why God’s provision of special grace to the elect does not result in God’s necessitation of the salvation of the elect or the necessitation of the punishment of the damned (210). In the final two chapters, Backus shows how Leibniz uses his concept of sacred history to explain God’s role in ‘running the world’. God uses sacred history as a mechanism for actualizing the best of all possible worlds. Leibniz then uses this conception of history to argue for a unique view of heresy (among other things). Briefly, heresy should not be an object of persecution because heresy is part of God’s actualization of the best of all possible worlds (212).

The project is ambitious and intriguing. Backus is right that philosophical interpretations of Leibniz tend to neglect the influence of Leibniz’s theological commitments on his philosophy. This goes back to Bertrand Russell’s influential interpretation of Leibniz as a closet atheist philosopher masquerading as religiously orthodox to appease his employers.2 While nobody accepts Russell’s thesis that Leibniz’s philosophy can be completely divorced from his theology, it has had a lingering influence on interpretations of Leibniz.3 Thus, Backus’ book purports to fill a gap in modern Leibniz scholarship.

Backus, however, fails to mention several scholars who explicitly examine the relationship between Leibniz’s theology and his philosophy. Robert Sleigh’s Leibniz and Arnauld, Michael Murray’s introduction to his translation of Dissertation on Predestination and Grace, Part 2 of Robert Adams’ classic Leibniz: Theist, Determinist, Idealist, and Maria Rosa Antognazza’s rich intellectual biography of Leibniz all discuss—to varying degrees—the historico-theological context that shaped Leibniz’s philosophical thought.4 Backus’ failure of engagement with these (and similar) scholars is disappointing in part because the reader is unsure whether and to what extent the present study extends or contradicts these earlier interpretations.

Nevertheless Backus rightly notes that examining Leibniz’s theological views has the potential to illuminate the philosophical positions for which he is more widely known. Unfortunately, the examination undertaken here does not take us far in providing such illumination. We can see this by taking a closer look at her treatment of one key theme in Leibniz’s work: the nature of freedom.

One problem with Backus’s treatment of Leibniz’s views on freedom is that she never establishes for the reader the problem Leibniz’s theory purportedly aims to solve. Briefly, Leibniz has two problems of freedom: one pertaining to creaturely freedom and the other to divine freedom. In the Confessio philosophi (an early work written in 1672-73), Leibniz made his first attempt at crafting a comprehensive theodicy. In that dialogue, Leibniz formulates the following argument:


(1)  The existence of God is necessary.

(2)  Sins in this world follow from God’s existence

(3)  Whatever follows from the necessary is necessary.

(4)  Therefore, sins in this world are necessary.5


This puzzle brings out a connection between the two problems of freedom. If (4) is true, then God does not freely create and human beings do not sin freely.

The solution, in the Confessio, is that the argument fails to distinguish between two different modes of necessity, per se necessity and hypothetical necessity. Leibniz ultimately denies that whatever follows from something necessary per se is necessary per se. Something hypothetically necessary (i.e., possible per se but necessary given the supposition of some further thing) might follow from the necessary per se. For example, God is necessary per se, but the existence of this world is necessary only given God’s decree to create this world. So (3) is false. Backus does note the role of the per se modalities in Leibniz’s theodicy (98), but the exposition does not explain the motivation for introducing the concept.

One problem with Leibniz’s ‘modal solution’ is that it doesn’t work. As Leibniz later realizes, necessity of the consequence and necessity of the antecedent entails necessity of the consequent. Suppose that we have the following argument:


(a)  (If God decrees that the best world is actual, then this world is actual)

(b)  (God decrees that the best world is actual)

(c)   Therefore, (This world is actual)


Evidence for (b) comes from the fact that God is necessarily morally perfect and moral perfection demands doing whatever is best. In 1684, Leibniz elegantly captures the problem with the ‘modal solution’ in the following passage:

It seems that the formal reason for the existence of contingent things is that they are pleasing to the necessary Being. But isn’t it possible that what does not exist is pleasing to the necessary Being? Without doubt, it is possible, but it is not possible that those things are more pleasing. Therefore it is not possible that these things exist. A difficulty that must be solved.6

The modal solution to the problem of divine freedom requires supplementation. Leibniz develops the concept of moral necessity to show that the necessity operator in (b) is not the same kind of necessity operator in (a). Backus notes the use that Leibniz makes of moral necessity (99). But, again, she does not situate the problem by showing that moral necessity purportedly remedies a fundamental defect in the deployment of the per se modalities in his original theodicy.

Another problem not specifically noted by Backus is that Leibniz is vague about the specifics of moral necessity. He claims that it is a weaker modality than physical necessity but strong enough to guarantee determination. But, as several of Leibniz’s correspondents note (e.g., Goldbach, Remy, and Jacquelot), moral necessity seems to collapse into metaphysical or logical necessity. To these powerful objections, Leibniz usually lapses back into the (hopeless) strategy of deploying the per se modalities.7 And Backus seems unaware of the problematic nature of moral necessity. To advance the debate, we need a proposal of what moral necessity is and why that form of necessity does not collapse into other modalities.

There is, however, the second problem of freedom. This problem of human freedom stems from the Leibnizian doctrine that every predicate contained in any true sentence about a subject is contained in the concept of that subject (known as Leibniz’s Doctrine of the Complete Individual Concept). This appears to preclude creaturely freedom because all courses of action are closed except one (namely, that course of action that will make true the propositions that contain those concepts included in the creature’s complete concept). Hence, among other things, human sins are not free and, because of this, humans are not blameworthy for their sins. In response to this problem, Leibniz invokes the concept of ‘inclination without necessitation’, but the foundation of that solution seems to rest ultimately on the coherence of moral necessity.

In her treatment, Backus makes three claims about how Leibniz solves this puzzle of human freedom. Suppose that we are interested in explaining why Judas is blameworthy (hence free) for his betrayal of Jesus. Backus argues that, for Leibniz, Judas is blameworthy because Judas has an ability to do otherwise (i.e., an ability to avoid betraying Jesus) (106). Second, there are other per se possible worlds that contain a Judas that does not sin (supposedly this second claim is the truth-maker for the first claim, though Backus does not make this connection explicit) (80). And, third, Judas has a power over what he wills (112) such that he can spontaneously avoid betraying Jesus (76). This interpretation is, however, hard to sustain. Leibniz consistently denied trans-world identity throughout his career, so that there is no such thing as a possible world that contains a different (non-sinning) version of Judas. An example: “You will…ask why God did not give you more strength. I respond: if He had done that, you would not exist, for He would have produced not you, but rather another creature.”8 Even if we ignore these denials, the interpretation offered by Backus presupposes a cogent, plausible account of moral necessity. And, as noted above, we lack a cogent, plausible account of moral necessity.

Unfortunately, Backus never does the heavy lifting needed to advance the frontier. We can see this, for example, in the following passage (here, Backus discusses why God’s provision of grace does not threaten creaturely freedom):

The only external impulse [in the action of intelligent substances] is the cooperation of God who orders everything for the best, and this best includes a certain number of sins committed freely and spontaneously by intelligent substances. God can offer reasons to the human mind that incline it to the good but the world is by its very nature such that sin must still take place. This of course is a point not about predestination, but about God’s knowledge of how all individuals that he created would behave, a knowledge that does not stop them from acting freely and contingently (75).

While Backus clearly gestures at the problem of human freedom here, the solution is hard to discern. If God necessarily orders everything for the best, then in what sense is there free action? What is the inclination of human beings to action that falls short of necessitation? And how is God’s perfect foreknowledge (based on knowledge of complete concepts) consistent with free action? It’s not that there are no proposed answers to these questions, but Backus doesn’t even acknowledge that any answers are needed! This might be acceptable for a purely historical project, but Backus clearly takes the book to be “reconstructing as accurately as possible Leibniz’s thought and intellectual context” (2).

In addition to the less than precise treatment of philosophical issues, Backus makes a number of claims that seem hard to defend. For example, she claims, contrary to almost every interpreter, that Leibniz endorses trans-world identity (he doesn’t: see A VI, 4 1639; A VI, 3 148). She claims that Leibniz’s per se modalities resemble Kant’s analytic/synthetic distinction, which is implausible (Leibniz maintained that all propositions, including hypothetically necessary ones, are analytically true). And she makes the surprising claim that “Leibniz’s notion of necessity, contingency and possibility is [sic] remarkably stable” (92). It seems clear, however, that Leibniz tries out a number of different theories of freedom during his career. The evidence of this is that Leibniz, in different writings, denies (2), (3), (a), and (b) from the above arguments. In some places, he accepts (4) and (c). Leibniz’s views seem to range widely across times and texts.

Some of these confusions are serious (like the trans-world identity claim), while others are minor annoyances. But the lack of care betrays a general unwillingness to engage with the philosophical aspects of Leibniz’s thought in these areas. One unintended consequence of this approach is that Backus thereby drives an unnecessary wedge between Leibniz’s theology and his philosophy. For instance, she mentions that Leibniz’s theories of necessity and contingency were more central to his interests than predestination (61). Similarly, Backus states that: “Leibniz’s view of predestination is not a theological one” (74). But Leibniz’s reflections on necessity and contingency are tied to his theodicy. And producing an account of necessity and contingency is part of building a theory of predestination (and Leibniz explicitly ties these two together in his Dissertation on Predestination and Grace). So it is not clear that we can separate Leibniz’s interest in necessity and contingency from predestination this cleanly. Backus provides no account of the distinction between the philosophical and the theological, though it is clear that the distinction is doing some work for her (see also 83). To further the confusion, Backus claims elsewhere that: “…it proves very difficult, in fact impossible, to say where Leibniz’s philosophy ends and his theology begins…” (139). These statements cannot stand together, but it is never clear which side Backus comes down on.

The book does, however, do some important scholarly work. The history of reformed theology is extensive, and the overview of the theological positions of various figures in Leibniz’s orbit (like Jablonski, Huet, and Newton) help to situate Leibniz’s philosophy in its historical context. Additionally, the discussion of Leibniz’s philosophy of history is quite original. Most work in this area is not in English, so Backus’ two chapters will be essential for English-speaking scholars looking to dip into this area of Leibniz’s thought.

As a result, the primary value of the book is the historical material, not the discussion of philosophical problems. To someone well versed in various interpretive disputes, the book could provide interesting source material for innovative developments in Leibniz research (although the historical material is difficult, as Backus tends to rush through definitions of various theological positions). But the interpretive errors and lack of connection to established interpretive disputes makes the book difficult for non-experts to use. And the obscurity of Leibniz’s philosophy makes it difficult for non-specialist theologians to see how Leibniz’s thinking overlaps with the religious disputes of the early modern period. That’s a shame, as Leibniz was one of the few early modern philosophers who was also a sophisticated theologian. It would’ve been nice to have a book that allowed both theologians and philosophers to appreciate the subtleties of Leibniz’s philosophical theology.

A book like Backus’ is sorely needed. I agree wholeheartedly with the main thesis of her project, though the execution leaves something to be desired. In the end, Leibniz: Protestant Theologian probably will not be the last word on this topic. It represents an interesting, and curiously underdeveloped, gap in Leibniz scholarship.

1 In this review, A = Gottfried Wilhelm Leibniz: Sämtliche Schriften und Brief, ed. Deutsche Akademie der Wissenschaften (Darmstadt and Berlin: Akademie Verlag, 1923- ). Cited by series, volume, and page, e.g., A VI, 4 1447.

2 Bertrand Russell, A Critical Exposition of the Philosophy of Leibniz (Cambridge: Cambridge University Press, 1900).

3 Examples: C.D. Broad, Leibniz: An Introduction (Cambridge: Cambridge University Press, 1975); Catherine Wilson, Leibniz’s Metaphysics: A Historical and Comparative Study (Princeton: Princeton University Press, 1989); Daniel Garber, Leibniz: Body, Substance, Monday (New York: Oxford University Press, 2009).

4 Robert Sleigh, Leibniz and Arnauld (New Haven, CT: Yale University Press, 1990); Robert Adams, Leibniz: Determinist, Theist, Idealist (Oxford: Oxford University Press, 1994); Maria Rosa Antognazza, Leibniz: An Intellectual Biography (Cambridge: Cambridge University Press, 2009); G.W. Leibniz, Dissertation on Predestination and Grace (= The Yale Leibniz), translated, edited, and with an introduction by Michael J. Murray (New Haven, CT: Yale University Press, 2011).

5 A VI, 3 127.

6 A VI, 4 1460.

7 See, e.g., Leibniz to Goldbach (Mar. 15, 1713) in Opera Omnia, vol. 5 ed. L. Dutens (Geneva: Fratres De Tournes, 1768), 169: “Because an infinite number of worlds can be represented and distinctly conceived…and it is only the choice of the best…our world is contingent and not necessary absolutely but only morally…”.

8 A VI, 4 1639 (written ca. 1689 or 1690).


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