Staying Optimistic: The Trials and Tribulations of Leibnizian Optimism

Authors: {'first_name': 'Lloyd', 'last_name': 'Strickland'}


The oft-told story of Leibniz’s doctrine of the best world, or optimism, is that it enjoyed a great deal of popularity in the eighteenth century until the massive earthquake that struck Lisbon on 1 November 1755 destroyed its support. Despite its long history, this story is nothing more than a commentators’ fiction that has become accepted wisdom not through sheer weight of evidence but through sheer frequency of repetition. In this paper we shall examine the reception of Leibniz’s doctrine of the best world in the eighteenth century in order to get a clearer understanding of what its fate really was. As we shall see, while Leibniz’s doctrine did win a good number of adherents in the 1720s and 1730s, especially in Germany, support for it had largely dried up by the mid-1740s; moreover, while opponents of Leibniz’s doctrine were few and far between in the 1710s and 1720s, they became increasing vocal in the 1730s and afterwards, between them producing an array of objections that served to make Leibnizian optimism both philosophically and theologically toxic years before the Lisbon earthquake struck.

Keywords: LeibnizOptimismBest worldLisbon earthquakeEvilWolff 
 Accepted on 25 Oct 2018            Submitted on 08 Sep 2018

The oft-told story of Leibniz’s doctrine of the best world, or optimism, is that it enjoyed a great deal of popularity in the eighteenth century until the massive earthquake that struck Lisbon on 1 November 1755 destroyed its support. This story has a long history. More than a century ago, Wilhelm Lütgert claimed that ‘England, France and Germany were dominated by optimism at the beginning of the 18th century’ (Lütgert 1901, 1), but that ‘The [Lisbon] earthquake unsettled the unthinking comfort of optimism’ (Lütgert 1901, 41).1 Decades later, Harald Weinrich wrote: ‘For all of Europe, the Lisbon [earthquake] marks the turning point of the [eighteenth] century, when the optimism of the Enlightenment suddenly turns into pessimism’ (Weinrich 1971, 71). More bluntly still, Jürgen Moltmann claimed that ‘The optimistic conception of the world held by the thinkers of the Enlightenment collapsed in the experience of the Lisbon earthquake of 1755’ (Moltmann 1983, 565). More recently, Thomas P. Saine insisted:

In spite of all the questionable and even naive assumptions that went into making God’s ways intelligible to man, the efforts of Leibniz, Bishop King, and their many successors seem to have satisfied the eighteenth century’s needs for a good while, at least until the 1755 Lisbon earthquake shattered the rosiest glasses of the time (Saine 1997, 103).2

There are two curious features of such claims. First, they are invariably made without any supporting evidence, as if they were somehow self-evident or self-confirming. Second, they are surprisingly vague about how exactly the Lisbon earthquake is supposed to have undermined optimism. It is unclear, for example, whether the claim is that the earthquake led declared optimists to abandon optimism, or whether it resulted in optimism gaining fewer adherents, or both. As it happens, it doesn’t matter which of these possible claims is intended as all are false. Simply put, the idea that optimism was devastated by the Lisbon earthquake is a commentators’ fiction that has become accepted wisdom not through sheer weight of evidence but through sheer frequency of repetition.

In this paper we shall examine the eighteenth-century reception of Leibniz’s doctrine of the best world in order to get a clearer understanding of what its fate really was. As we shall see, while Leibniz’s doctrine did win a good number of adherents in the 1720s and 1730s, especially in Germany, support for it had largely dried up by the mid-1740s; moreover, while opponents of Leibniz’s doctrine were few and far between in the 1710s and 1720s, they became increasingly vocal in the 1730s and afterwards, between them producing an array of objections that served to make Leibnizian optimism both philosophically and theologically toxic years before the Lisbon earthquake struck. As we shall also see, many of these objections stemmed from misunderstandings of Leibniz’s doctrine, which appears to have been better known in outline than in its details. To show this, I shall begin in section I by sketching out Leibniz’s doctrine of the best world, while its reception over the chief part of the eighteenth century shall be the subject of the remaining sections.

I. Leibniz’s doctrine of the best world

Leibniz developed his doctrine of the best world early in his career, certainly by the time he wrote his Confessio philosophi [The Philosopher’s Confession] in 1672/3, but most of his writings on it were left unpublished in his lifetime and in many cases appeared only decades or even centuries after his death. His most extended treatment of the doctrine is to be found in a late work, the Théodicée [Theodicy], which he published in 1710, six years before his death. Although the shorter treatments found in two posthumously-published essays, namely ‘Principles of nature and grace’ (Leibniz 1718) and ‘Monadology’ (Leibniz 1720), were also occasionally drawn upon, the Theodicy became the principal source of information about his doctrine throughout the eighteenth century. Accordingly, the following sketch of his doctrine is drawn entirely from that book.

In the Theodicy Leibniz explains not just why God would create the best world but also which features make our world the best. Let’s begin with why Leibniz thought God would create the best. Key to his thinking is the belief that in God’s mind there exist the ideas of all possible things (that is, those which do not contain or imply contradiction) and of all possible combinations of these things, namely possible worlds (that is, sets of mutually compatible possible things and laws, each set having its own determinate history). Leibniz claims that God would create the best of these possible worlds, arguing that as God is omnipotent he can create any possible world; as he is omniscient he knows which possible world will be the best; and as he is perfectly good he will choose only the very best (Leibniz 1985, 128, §8). Although this argument might suggest that God was necessitated in his choice of the best world, as no other choice would seem to be consistent with his perfect nature, Leibniz insists that God’s choice was in fact free. In the Theodicy, Leibniz defines a free action as one that ‘consists in intelligence, which involves a clear knowledge of the object of deliberation, in spontaneity, whereby we determine, and in contingency, that is, in the exclusion of logical or metaphysical necessity’ (Leibniz 1985, 303, §288), and he argues throughout the book that God’s choice of the best world fits this description. He explains that God’s will is determined to choose the best because his will (like all wills) is naturally attracted to the perceived best course and his supreme intellect ensures that in his case the perceived best and the actual best are one and the same thing (Leibniz 1985, 199, §125; 269, §228; 428). Consequently the determination to the best stems from God’s own (perfect) nature rather than from anything external to him, and therefore he is exempt from constraint (Leibniz 1985, 61; 148, §45; 236, §175; 270, §230). Leibniz also denies that God could have been necessitated in his choice. If he had been, Leibniz supposes, it would follow that only the best world would be possible. Yet, he claims, we know this to be false since many other worlds can be conceived, indicating that they are possible (Leibniz 1985, 148, §45). Consequently, since there are other possible worlds, it cannot be the case that God was absolutely necessitated to choose the best (Leibniz 1985, 271, §234). Nevertheless, Leibniz allows that God’s choice was morally necessary since ‘the wisest should be bound to choose the best’ (Leibniz 1985, 270, §230), in the sense of satisfying ‘an obligation imposed by reason, which is always followed by its effect in the wise’ (Leibniz 1985, 395).

But what is it about our world that makes it the best? Leibniz explains that ‘in forming the plan to create the world, God intended solely to manifest and communicate his perfections in the way that was most efficacious, and most worthy of his greatness, his wisdom, and his goodness’ (Leibniz 1985, 164, §78, translation modified). God thus fills the world with his own perfections, principally power, knowledge, and goodness, which are shared by created things, albeit to an inferior degree:

The perfections of God are those of our souls, but he possesses them in boundless measure; he is an ocean, of which we have received only drops: there is in us some power, some knowledge, some goodness, but in God they are all complete (Leibniz 1985, 51, translation modified).

Accepting the NeoPlatonic idea that created things contain a degree of God’s essence or perfection, Leibniz supposed that the more variety of created things in existence the better, as this would effectively multiply God’s own perfections in the world:

Midas found himself less rich when he had only gold. And besides, wisdom must vary. To multiply only the same thing, however noble it may be, would be superfluity, and poverty too: to have a thousand well-bound Virgils in one’s library, to sing always the airs from the opera of Cadmus and Hermione, to break all the china in order only to have cups of gold, to have only diamond buttons, to eat nothing but partridges, to drink only Hungarian or Shiraz wine, would one call that reason? (Leibniz 1985, 198, §124, translation modified).

Yet the best world is not simply a well-varied collection of things, as Leibniz insists that the best ‘includes the whole sequence, the effect and the process’ (Leibniz 1985, 269, §228). By ‘the process’ Leibniz here means the simplicity of the ways and means God employs in the workings or operation of the world. His decision to identify simplicity as a worldly good owed much to his contemporary, Nicolas Malebranche (1638–1715), who had argued that God, as the artisan or craftsman par excellence, would make use of the simplest possible means to bring about his intended effect, as anything else would not be in keeping with supreme wisdom (Malebranche 1992, 116). This meant that God would instantiate laws of nature, as opposed to acting on caprice, and that these laws of nature would be universal, regular and constant, but also very simple and very fertile in that they would be capable of producing a great variety of effects. Whereas Malebranche thought of simplicity of ways as merely a constraint on God, such that God would have to act in the simplest ways because that is most in keeping with his wisdom, Leibniz thought of it as something that conferred value upon a world in its own right, or rather as a component in the world’s perfection: ‘The two conditions of simplicity and productivity can even be reduced to a single advantage, which is to produce the most perfection possible’ (Leibniz 1985, 257, §208, translation modified). In the Theodicy, Leibniz does not indicate whether variety and simplicity can be simultaneously maximized or whether they are in tension and need to be traded off; unfortunately those writings in which he does discuss this matter more explicitly – in particular the Discourse on Metaphysics (written 1686; published 1846) – were not published until the nineteenth century.3

Although Leibniz often focuses on variety and simplicity in his characterization of the best world, elsewhere in the Theodicy he insists that ‘God was bound by his goodness … to make choice of such a world as should contain the greatest possible amount of order, regularity, virtue, happiness’ (Leibniz 1985, 431). It should be noted that this does not mean God would choose a world without sin and unhappiness:

It is true that one can imagine possible worlds without sin and misfortune, and one could come up with some, like stories of Utopias or Sevarambias, but in any case these same worlds would be very inferior to ours in goodness. I cannot show you this in detail, for can I know and can I represent infinities to you and compare them together? But you must judge with me ab effectu [from the outcome], since God has chosen this world as it is (Leibniz 1985, 129, §10, translation modified).

So stated, Leibniz’s doctrine of the best world is a good example of a priori reasoning in the pre-Kantian sense of reasoning that runs from cause to effect, for it is from a consideration of the nature of God alone (cause) that Leibniz infers that this must be the best world (effect). He does not think it possible to argue in reverse, that is, from the fact that this is the best world (effect) to the supreme perfection of God’s nature (cause), because it is impossible for us to determine, through experience, that ours is the best world. Similarly, Leibniz would not accept that experience could disprove that our world is the best, since our experience does not extend to this world in its entirety, let alone other possible worlds in their entirety.

Nevertheless, one might suppose that Leibniz’s claim that our world contains the greatest happiness sits uneasily with the fact that many people have led unhappy lives. While Leibniz acknowledges such unhappiness, he does not consider it to be evidence against his claim that our world contains the greatest possible happiness, principally because he construes the world as the entire created universe from the point of creation through the remainder of its never-ending existence (Leibniz 1985, 128, §8; 249, §195), which means that it includes what has traditionally been described as the afterlife. While Leibniz accepts (or at least assumes) the traditional Christian view that some people will be consigned to eternal punishment after this life (Leibniz 1985, 288, §263), he holds that for many the afterlife will be an eternity of happiness, apparently supposing that much of the happiness in the best world will occur then. As such, present misery will be vastly outweighed by the eternal happiness to come.

In devising his conception of the best world, Leibniz’s principal concern is to defend God’s justice and holiness in the face of the world’s evils, of which he recognizes three kinds, namely metaphysical, physical, and moral, which are characterized thus: ‘Metaphysical evil consists in mere imperfection, physical evil in suffering, and moral evil in sin’ (Leibniz 1985, 136, §21). Leibniz explains that all creatures possess metaphysical evil by virtue of lacking some of God’s perfections. This in turn leads to moral evil, for as creatures are limited and have insufficient wisdom to always know what the right actions are, they easily fall into sin:

For we must consider that there is an original imperfection in the creature before sin, because the creature is essentially limited, which means that it cannot know everything, and that it can be deceived and make other mistakes (Leibniz 1985, 135, §20, translation modified).

As for physical evils, Leibniz points out that while ‘God can follow a simple, productive, regular plan’ this would not be ‘always opportune for all creatures simultaneously’ (Leibniz 1985, 260, §211). After all, maximizing variety would lead to the creation of predators and parasites, which would naturally cause harm to other creatures, while a network of universal laws of nature would lead to injuries and deaths, for example for those creatures unfortunate enough to lose their footing on cliff edges. However, Leibniz (1985, 137, §23; 276, §241) insists that the physical evils experienced by human beings are not simply accidental by-products or side-effects of variety and simplicity but instead play a specific role in God’s design, serving either as punishments for sins or to prepare us for future happiness, since suffering can lead to the amendment or improvement of character.

Before I finish my sketch of Leibniz’s doctrine of the best world, I will note one aspect of it that was often overlooked in the eighteenth century and indeed is often overlooked even today, namely that it could inspire contentment in this life. Leibniz (1985, 54–55) argues that anyone who understands his doctrine could have no complaint about the way the world is governed, secure in the knowledge that God is so concerned with the welfare of all virtuous human beings that he will ensure all will turn out well for them. The virtuous thus have every reason to feel contentment and satisfaction in this life, even if they suffer inconveniences or come up against other troubles. Hence Leibniz conceives of his optimism not just as a theoretical doctrine but as one with great practical value, having the potential to bring about contentment and satisfaction in those who understand its import.

Having outlined Leibniz’s doctrine of the best world as found in the Theodicy, we turn now to its reception.

II. Early Reception

In the first years after its publication, the Theodicy was widely reviewed in British, French, and German journals, often quite positively. But while each of the reviewers mentioned Leibniz’s doctrine of the best world, they did so neutrally, simply outlining Leibniz’s claims without indicating any support or criticism (see [Anon.] 1710a, 407–408; [Anon.] 1710b, 322–324; de la Roche 1711, 257; Wolff 1711, 113, 116–117, 119, 161, and 164; [Anon.] 1713, 1186–1187). The only major treatment of Leibniz’s doctrine that appeared during his lifetime was a hostile one, in a book entitled Doctrinae orthodoxae de origine mali contra recentiorum quorundam hypotheses modesta assertio [A Modest Statement of Orthodox Doctrine on the Origin of Evil Against the Hypotheses of Certain Recent Authors] (1712), written by Georg Christian Knoerr (1691–1762), who was at the time a Master’s student at the University of Jena, and the Lutheran theologian and philosopher Johann Franz Budde (1667–1729). Despite their hostility to Leibniz, Knoerr and Budde do not object to his claim that God created the best world, even arguing that it can be supported scripturally, something Leibniz himself did not do. Alluding to Genesis 1.31, which states that after creating the world and everything in it ‘God saw all that he had made, and it was very good’, Knoerr and Budde (1712, 4) insist that a lexical analysis of the final two Hebrew words of this passage (טוֹב מְאֹד) reveals that the word often translated as ‘very’ (מְאֹד, Latin valde) is in fact a superlative modifier, making the two-word combination equivalent to the Latin ‘optimum’ (best).4 But while they accept that the world God originally created was the best, they flatly deny that it remained so. Knoerr and Budde claim (1712, 4; cf. 6, 79, and 85) that what made the world the best when it left God’s hands was the complete absence of any moral or physical evil therein. The world today is of course overrun with such evils, and in true Augustinian fashion they blame this on the fall of man, which plunged the world into corruption. Thus for Knoerr and Budde, the true best world is the one that existed prior to the fall of man; had the fall not occurred the world would have remained free of evil and hence remained the best, but since the fall did occur, our world ceased to be the best. According to them, Leibniz’s mistake is to ignore the fundamental Christian dogma of the fall, which enables him to suppose – wrongly – that a world without evil would in fact be worse than ours:

The illustrious gentleman [sc. Leibniz] allows that a world without sin and misfortune can be imagined but that such a world would be inferior to ours…5 Our response: not only can a world without sin and misfortune be imagined but in fact it actually existed in the state of integrity, and indeed that world was not inferior to ours but was in fact the best. For the prelapsarian world must be set against the postlapsarian world (although, as said above, these things are not granted by this excellent man) because the state of the present world does not flow harmoniously from the nature or the idea of the antecedent world (Knoerr and Budde 1712, 78).

Moreover, they argue that to declare our world the best simpliciter, as Leibniz does, leaves no room for another key Christian dogma, that Christ incarnated and sacrificed himself in order to redeem a corrupt world and bring it back to its original state: ‘according to the testimony of Holy Scripture, Christ came, sent by God, to restore the best world that beforehand had been corrupted by sin’ (Knoerr and Budde 1712, 81). As we shall see, the charge that Leibniz’s doctrine of the best world is at odds with key Christian dogmas was to become a common one among his opponents.

III. Acceptance and Denial (1720s)

However, this early attack did not prevent Leibniz’s doctrine of the best world gaining a foothold, especially in Germany, where it became a popular doctrine in the 1720s. This was to no small extent due to its endorsement in Christian Wolff’s Vernünfftige Gedancken von Gott, der Welt und der Seele des Menschen, auch allen Dingen überhaupt [Reasonable Thoughts about God, the World, the Human Soul, and Just About Everything Else] (1720).6 Of course, the doctrines of the master rarely remain pure in the hands of his disciples, and so it is with Leibniz’s optimism, which was often reshaped to a greater or less extent by the sympathetic hands through which it passed. In Wolff’s case, Leibniz’s understanding of perfection – couched in terms of variety and simplicity – was replaced by Wolff’s own definition:

The perfection of the world consists in the agreement of everything that is simultaneous and successive, that is, in the particular grounds, which everything has, always resolving into some sort of common ground. The greater this agreement, the greater the perfection of the world (Wolff 1720, 386, §701).

Wolff apparently based this definition on one given to him by Leibniz in a letter written in 1715 where he had advised Wolff that ‘the perfection a thing has is greater, to the extent that there is more agreement in greater variety, whether we observe it or not’ (Leibniz 1989, 233). This echoes Leibniz’s longstanding definition of harmony as unity in variety or plurality, as found, for example, in his Confessio philosophi of 1672/3 (Leibniz 2005, 45). Wolff’s definition of worldly perfection was subsequently adopted in the first full-length defence of Leibnizian optimism, namely De origine et permissione mali, praecipue moralis, commentatio philosophica [Philosophical Treatise on the Origin and Permission of Evil, Especially of Moral Evil] (1724)], by the philosopher and mathematician Georg Bernhard Bilfinger (1693–1750). Bilfinger condenses Wolff’s definition of perfection to ‘agreement in variety’ (Bilfinger 1724, 39, §78), and goes on to define imperfection as an absence of agreement (Bilfinger 1724, 66, §114). Lacking the means to illustrate how this manifests in the world, Bilfinger resorts to a legal example: the choice of twenty senators may be said to possess supreme perfection if it is made by unanimous consent, while abstentions or dissent will introduce imperfection (Bilfinger 1724, 66–67, §114). Bilfinger also departs from Leibniz when claiming that the best world is the one with the least amount of evil (Bilfinger 1724, 53–54, §97), but otherwise he stays very close to the Theodicy, often citing it to reinforce his definitions and arguments.

Four years later, Bilfinger’s aim of producing a more orderly presentation of many of the key claims of Leibniz’s Theodicy was taken to its extreme by the philosopher, theologian, and mathematician Michael Gottlieb Hansch (1683–1749) in his Godefridi Guilielmi Leibnitii, principia philosophiae, more geometrico demonstrata [The Principles of Leibniz’s Philosophy, Demonstrated in the Geometric Manner] (1728). As the title indicates, the aim of Hansch’s book is to demonstrate the principles of Leibniz’s philosophy in the geometric manner, which involves utilising the apparatus of definitions, axioms, theorems, demonstrations, corollaries, and scholia.7 Notably, Hansch bases his claims about the best world not on the Theodicy but on the ‘Monadology’, in which Leibniz (2014, 25) suggests that the greatest perfection is to be found in a world containing an infinity of monads each expressing the others from its own particular point of view, a thought not found in the Theodicy. This leads Hansch to claim that ‘The greatest perfection of the world is the absolute reality of all parts of the world connected to each other as much as possible’ (Hansch 1728, 56), which in turn leads him to suppose that the best world is the one in which there is ‘a universal pre-established harmony of things’ (Hansch 1728, 62). However, Hansch understands by this not Leibniz’s famous pre-established harmony between the soul and body, but rather such a universal connection between all simple and composite beings ‘that God’s intellect observes, in any simple or composite being whatsoever, all the things that have been, are, and will be in all other simple and composite beings’ (Hansch 1728, 62).

Not all defences of Leibniz’s optimism were as fully-fledged as those of Bilfinger and Hansch, however. In 1725, there appeared an essay entitled ‘Demonstratio theologico-philosophica, quod idea electi mundi optimi a Deo, salva ejus sapientia & libertate, removeri nequeat’ [Theological-Philosophical Demonstration that the Idea of the Choice of the Best World by God Cannot Be Discarded without Detriment to His Wisdom and Freedom], credited to Almonius Utinus, the pseudonym of Johann Christoph Harenberg (1696–1774), an evangelical theologian who was at the time Rector of the seminary in Gandersheim. As the title of his essay suggests, Harenberg’s aim is merely to defend the idea that God would choose the best. Harenberg’s defence is not especially novel, largely echoing Leibniz’s own position that an infinitely wise and infinitely good God would surely choose the best. After all, he says, ‘If this world … is not the best then God the creator has employed insufficient wisdom and insufficient goodness: blasphemous nonsense!’ (Harenburg 1725, 70).

While Leibniz’s doctrine of the best world gained traction in Germany during the 1720s, support was slow to develop elsewhere. During this time, the only advocate of note outside of Germany was the Oratorian Claude François Alexandre Houtteville (1686–1742), who defended optimism in his Essai philosophique sur la providence [Philosophical Essay on Providence] (1728). Curiously, despite drawing many of his ideas from Leibniz’s Theodicy, Houtteville mentions Leibniz just once, in the preface (Houtteville 1728, xvi), and otherwise gives no indication of the source of his ideas. Houtteville (1728, 226–228) reaches the doctrine of the best world in the same way Leibniz had, but differs in his understanding of what makes the world the best. Indeed, his descriptions of the best world are numerous but invariably abstract. For example, he describes the best world as ‘the most beautiful, the most ordered’ (Houtteville 1728, 181, cf. 193), the one that has ‘a prevalence of grandeur and goodness over the others’ (Houtteville 1728, 188), ‘the most regular of all those possible’ (Houtteville 1728, 190), and the one in which ‘everything is the best ordered, the most symmetrical’ (Houtteville 1728, 264). Unfortunately, he does not develop or offer any further detail on any of these claims. Houtteville also departs from Leibniz on the question of the place of evil in the best world. While Leibniz had supposed that physical evils contribute to the perfection of the best world, Houtteville (1728, 249–250) appears to accord them no positive value, seeing them as just necessary parts of the best plan.

While support for Leibniz’s optimism was growing, its rise did not go unchallenged, and by the mid-1720s it had come under its first concerted attacks since 1712. This occurred both in Germany, through Christian Eberhard Weismann (1677–1747), then associate professor of theology at the University of Tübingen, and in France, through Du Pont-Bertris, the pseudonym of an author whose identity is still unknown. Weismann’s chief objection is that optimism leaves no room for God’s freedom:

It is not apparent how the will of God is a free cause of existence of all things if God, by the perfection of his own wisdom, is determined to the choice – or rather to the acceptance – of only one [world], which alone is called the best, and if there is no indifference of freedom in that (Weismann 1725, 148).

Weismann considers Leibniz’s attempts to preserve God’s freedom but finds them unsatisfactory. He rejects Leibniz’s distinction between moral and absolute necessity on the grounds that God’s choice can be traced back to his essential – and hence necessary and immutable – attributes, which makes his choice not only morally but also absolutely necessary. He also dismisses Leibniz’s claim that worlds other than the best are possible inasmuch as they involve no contradiction, arguing that what matters when determining whether a world is possible or not is whether God is actually able to create it:

Therefore, because all other worlds that can be imagined are not the best world, and not to choose the best world conflicts with all decency and all divine perfections, especially God’s wisdom and goodness, it is most correctly concluded, in accordance with the rule of theologians … that all other worlds, which can only be less perfect, are in fact impossible with respect to God, and indeed cannot be chosen by him (Weismann 1725, 150).

Like Knoerr and Budde, Weismann also charges that Leibniz’s doctrine of the best world is theologically problematic, ignoring as it does the central event of the fall. ‘[T]he first state of integrated nature,’ he explains (Weismann 1725, 164), was free of vice, sin, and imperfection, but that cannot be said of the world after the fall: ‘we firmly deny that the world remained the best with vice and sin added, as though vice and sin were a condition without which the best world would not exist’ (Weismann 1725, 167).

In a not dissimilar vein, Du Pont-Bertris expressed incredulity that a world without evil was not possible, evidently assuming in the process that such a world would be better than ours:

No matter how ingenious Leibniz’s idea is, it seems that it does not put a stop to the objections. For ultimately, in all these possible worlds, evil is always assumed to be mixed with good, and it is far from clear why it is. Is there, then, no possible world wherein all evil is banished? And is the idea of an infinite goodness assisted by a power that is also infinite going to lead us to conclude that such a world cannot come out of the hands of God? (Du Pont-Bertris 1726, 441–442)

As it happens, Leibniz (1985 129, §10) had addressed this very point in the Theodicy, as we have seen, claiming there that a world without sin and evil was possible but was evidently not as good as our world since it had not been chosen by God, who would choose only the best. Du Pont-Bertris’ oversight naturally leads one to wonder whether he had actually read the Theodicy, or got his information about it from a different source. As we shall see, such a question could be asked about many of those who joined in the eighteenth-century debate about optimism.

IV. Mixed Fortunes (1730s)

In many ways, the fortunes of Leibnizian optimism in the 1730s differed little from its fortunes in the 1720s, in that it attracted plenty of support and not a little censure. But while opponents of optimism in the 1720s trained their fire on Leibniz’s version of the doctrine or some close approximation thereof, this was not always the case in the 1730s and afterwards, following the appearance of a new form of optimism in 1733, in a work by the English poet Alexander Pope (1688–1744). In his poetic masterpiece Essay on Man, Pope sought to vindicate God’s ways to man, which in part involves acknowledging that the world God created was the best:

Of Systems possible, if ’tis confest,

That Wisdom infinite must form the best (Pope 1733, 5).

Pope (1733, 6, 14) linked the notion of the best world with the old idea of the great chain of being, in which every creature was thought to occupy a unique place as part of a harmonious and perfect whole wherein all possible degrees of perfection, from nothingness up to God, were exemplified.8 Since in such a system nothing could be changed or removed without detriment to the whole, Pope was led to the conclusion that ‘Whatever is, is RIGHT’ (Pope 1733, 16).

Speculation soon arose as to whether Pope had been influenced by Leibniz. Pope (1956, IV: 164) himself later insisted that he had not read a line of Leibniz at the time he composed his poem, but not all were convinced by this. Voltaire (1784, 110–111) claimed that in framing his poem Pope had expounded Leibniz, Shaftesbury, and Bolingbroke. Others sought to stress the differences between the poet and the philosopher. Lessing and Mendelssohn (1755, 55–56), after comparing Pope’s view with Leibniz’s and noting a number of areas of disagreement, argued that Pope was inspired not by Leibniz, or even much by Shaftesbury (who – they claim – Pope misunderstood), but by William King’s De origine mali [On the Origin of Evil] (1702).

Nevertheless, after 1733, it was not uncommon for Leibniz’s form of optimism to be discussed alongside Pope’s or for the two to be conflated, this being helped in no small part by the writings of the Swiss theologian and philosopher Jean Pierre de Crousaz (1663–1750). In 1737 and 1738, Crousaz published two books against Pope, in which he also occasionally attacked Leibniz, albeit without ever citing him. Crousaz’s chief complaint against Leibniz was that his doctrine of the best world destroys divine freedom, for God ‘is conceived under the necessity of creating such a world as we see, and deprived of freedom of choice’ (Crousaz 1737, 106). Crousaz’s decision to discuss Leibniz and Pope together inspired others to do the same, even some supporters of optimism. For example, in a short essay entitled ‘A View of the Necessitarian or Best Scheme: Freed From the Objections of M. Crousaz, in His Examination of Mr. Pope’s Essay on Man’ (1739), Scottish philosopher William Dudgeon (1705/6–1743) sought to defend the optimism of both Leibniz and Pope against the objections of Crousaz, although like Crousaz he does not cite Leibniz once. Nevertheless, Dudgeon confidently construes both Leibniz and Pope as modern proponents of the Stoic doctrine of the world’s necessity, thereby ignoring Leibniz’s claims for the contingency of both the world and God’s choice thereof. Dudgeon’s cheerful acceptance that God had created the best world out of necessity (‘His essential goodness necessarily determined him to will creation’) certainly was unusual in the eighteenth century, but his decision to construe Leibniz and Pope as advocates of the same doctrine certainly was not (Dudgeon 1739, 7, cf. 12).

While Leibniz’s form of optimism would eventually be weakened by its association with Pope’s, it continued to flourish in Germany throughout the 1730s, though some of the ways in which it was presented would not have met with Leibniz’s approval. For example, in Erste Grunde der gesammten Weltweisheit [First Grounds of Whole Worldly Wisdom], Johann Christoph Gottsched (1700–1766) suggested that one could ascertain that our world is the best a posteriori:

He who wishes to observe with all his genius and attention everything that has happened in the world, and what he has encountered, will find that everything in it is very orderly arranged, and aims throughout at a greater perfection of the parts, or at least of the whole (Gottsched 1735, 230, §429).9

Gottsched’s claims were inspired by the flourishing natural theology movement and in particular the design argument, which to many proponents demonstrated the great perfection of God’s handiwork (even if few wanted to go as far as Gottsched and connect this claim with optimism). Gottsched’s book would be reprinted four times between 1735 and 1778, ensuring that his presentation of optimism won a great deal of exposure in Germany. Yet it was by no means the most influential apology for Leibnizian optimism that had appeared since the Theodicy. That accolade arguably belonged to Christian Wolff’s Theologia naturalis, methodo scientifica pertractata [Natural Theology Treated According to the Scientific Method]. Until 1725, Wolff had elaborated his philosophy in a series of lengthy German works, but in 1728 he began recasting his philosophy in a series of even lengthier Latin works. In 1736 there appeared the first volume of his Theologia naturalis, with the second emerging a year later. In this work, Wolff defends a broadly Leibnizian account of ‘the hypothesis of the best world’, as he calls it, albeit with a few adjustments of his own (Wolff 1736, 628–629, §672). For example, his claim that God, being sufficient unto himself, was indifferent as to whether to create or not (Wolff 1736, 401–402, §430), would have struck Leibniz as too strong, despite it being made in order to show that God was not necessitated. Nevertheless, Wolff is much closer to Leibniz in his account of God’s choice of the best. Wolff explains that God was able to survey all possible worlds on account of his omniscience (Wolff 1736, 114, §141). Because his will tends towards the best, which serves as his motive for acting, he ‘chooses this world over all the others on account of the greater perfection that belongs to it rather than to the others’ (Wolff 1736, 322, §325). Moreover, this qualifies as a free decision according to Wolff’s definition of freedom as ‘the faculty of spontaneously choosing, from many possibles, that which is pleasing’ (Wolff 1736, 402, §431), for as God is free from any internal and external constraint he determines himself to will whatever he wills (Wolff 1736, 320, §322), and so spontaneously wills whatever he wills (Wolff 1736, 320, §323). According to Wolff, that God is so constituted to be most pleased by the best does not prevent him from choosing it spontaneously, by his own determination (Wolff 1736, 320, §§322–323).

Wolff also sides with Leibniz in identifying God’s ultimate aim or end in producing the best world as ‘the disclosing of himself, that is, of his absolutely supreme perfection’ (Wolff 1736, 567, §608) in order to manifest his own glory (Wolff 1736, 570, §611; Wolff 1737, 331, §371). He further claims that God decided to permit moral evil in the best world for precisely the same reason (Wolff 1736, 570, §613). Interestingly, despite Wolff’s well-deserved reputation as an arch rationalist who drily and methodically deduces his claims from definitions, he opts to support key parts of his ‘hypothesis of the best world’ through appeals to scripture as well, something Leibniz and other proponents of optimism did not do. Thus he borrows Knoerr and Budde’s Hebraic lexical analysis of Genesis 1.31 in order to defend the general claim that God created the best world (Wolff 1736, 374, §406), while to bolster his claim that God’s ultimate end was to manifest his own glory he cites Romans 1.20 (Wolff 1736, 568, §609; 647, §687), John 2.11 (Wolff 1736, 570, §612), and Proverbs 16.4 (Wolff 1736, 647, §687). To support his assertion that God also permits evils for the same end he appeals to Romans 9.22–23 (Wolff 1736, 647, §687).

Wolff’s support for the best world doctrine in his Latin works inspired his supporters and expositors to come out in its favour also, though none sought to duplicate Wolff’s attempts to ground the doctrine in scripture, which is perhaps surprising in an age in which demonstrating conformity with scripture was still prized. Chief among Wolff’s expositors was Alexander Baumgarten (1714–1762), who endorsed optimism in his oft-reprinted Metaphysica [Metaphysics], first published in 1739. Baumgarten’s treatment of optimism is notable principally for its highly abstract characterization of the best or most perfect world (these being one and the same, he says): ‘the most perfect world embraces as many (1) simultaneous, (2) successive, and (3) as great beings as are compossible in the best world’ (Baumgarten 2011, 183 §437).10 Baumgarten also weaves the idea of interconnectedness into his understanding of the best world: ‘In the most perfect world there is the greatest universal nexus,11 harmony, and agreement that is possible in a world’ (Baumgarten 2011, 183, §441).

Despite the popularity of Baumgarten’s Metaphysica – it would be reprinted a further six times between 1743 and 1779 – it had much less impact on the optimism debate than Wolff’s Theologia naturalis. Indeed, Wolff would increasingly become the figurehead of optimism, supplanting Leibniz, at least in Germany. In this regard, a dissertation entitled De bonitate mundi biblica [On the Biblical Goodness of the World], published in 1737 by Immanuel Ernst Hahn (1711–1746), who would later become preacher at the orphanage in Dresden, was a sign of things to come. In this text Hahn defends and elaborates the position that had been first developed by Knoerr and Budde twenty-five years before, namely that God created the best world but the world did not remain the best. Hahn agrees with Knoerr and Budde that a lexical analysis of Genesis 1.31 proves that God created the best world, and he insists, as they had, that those who suppose our world is still the best have overlooked the fall and its effects. For ‘as Moses [in Genesis] spoke only of the state of the world that existed before the fall, it does not thereby follow that the present condition of the world is still the best’ (Hahn 1737, 37). Whereas Knoerr and Budde had levelled the objection against Leibniz, Hahn’s target throughout is Wolff, with Leibniz not mentioned once. While this would become increasingly common in the 1750s and 1760s, as we shall see, Hahn shows that even in 1737, optimism had ceased to be thought of as a peculiarly Leibnizian doctrine, at least in Germany.

Outside Germany, however, Wolff’s defence of optimism passed almost unnoticed, and what critiques of optimism there were invariably focused on either Leibniz or Pope or both. While Pope’s version of optimism attracted a lot of attention, Leibniz’s came back into the spotlight following the reprinting of his Theodicy in 1734. The reprinting prompted the Jesuit journal Mémoires pour l’histoire des sciences & des beaux-arts [Memoirs of the history of sciences and fine arts] to publish an extended review in 1737. Whereas an earlier review in the same journal (see [Anon.] 1713) was broadly positive, the later one, probably written by Louis-Bertrand Castel (1688–1757), a Jesuit mathematician and natural philosopher,12 was anything but. Castel’s review is notable for its introduction of the term optimism into the philosophical vocabulary. Suggesting that tant mieux [so much the better] adequately sums up Leibniz’s philosophy, Castel writes: ‘he [Leibniz] calls it the reason of the best or more cleverly still … the system of the best [l’Optimum], or optimism [l’optimisme]’ (Castel 1737, 207). Although ‘optimism’ may appear a straightforwardly descriptive term, it is quite clear that Castel intended it as pejorative, and it retained this association throughout the eighteenth century.13 Aside from this neologism, Castel’s review contributed little new to the debate over Leibniz’s doctrine, but it did round up a number of objections that heretofore had been scattered in the work of other opponents.

Castel’s chief concern is that Leibniz’s optimism strips God of free will and effectively reduces God to an automaton, leaving him ‘neither freedom of choice nor any kind of freedom’ (Castel 1737, 209–210). To Leibniz’s claim that supreme wisdom cannot fail to choose the best, Castel responds ‘The term choose is improper here: a necessary choice is not a choice’ (Castel 1737, 448). Castel also takes issue with Leibniz’s claim that our world, with all of its sin and evil, could be the best:

How can a learned man, a Christian … think that a world in which there is evil and sin could be the best world God can make? Sin alone is such a great evil that all the perfection of a world infinitely superior to this one could not even counterbalance it (Castel 1737, 214).

These two objections would continue to dog Leibnizian optimism in the decades that followed. The repetition of such stock objections would undoubtedly play a big part in the downfall of Leibniz’s doctrine of the best world, chipping away at its credibility.

Another factor that shaped the fate of Leibnizian optimism was that Leibniz’s Theodicy was, as Castel eloquently put it, ‘so vaunted and perhaps so little known’ (Castel 1737, 197). Nowhere is this more apparent than in Britain, where the book was rarely cited and seems to have been better known through the handful of extracts in English translation that had been published in the Memoirs of Literature in 1711 (see de la Roche 1711) than from first hand acquaintance with the book itself. These extracts were cited almost three decades later by Edmund Law (1703–1787) in his extensive notes on the English translation of William King’s De origine mali. When elaborating on King’s claim that there were more goods than evils in the world, Law refers his readers to a host of other thinkers, including ‘Leibnitz, Essais de Theodicee, or Memoirs of Lit. Vol. 3’ (King 1739, 475 note, cf. 445 note). Law cited the English-language extracts not because he had not read the Theodicy (in fact he cites it at times) but most probably because he was aware that they would be more accessible to his readers than Leibniz’s own book, which was not widely available in Britain and not at all in English translation. The lack of an English translation may explain, at least in part, not only why Leibniz’s doctrine of the best world failed to make many inroads in Britain but also why its British opponents were apt to conflate Leibniz’s optimism with that of Pope. It may also explain why those British thinkers who did not conflate these two versions of optimism nevertheless had a very sketchy understanding of Leibniz’s version, as we shall see in due course.14

V. The Last Hurrah (1740–1744)

While support for Leibniz’s doctrine had remained strong in the 1720s and 1730s, at least in Germany, it dissipated in the 1740s, with the doctrine making its last hurrah in the first half of that decade. It is curious that, despite the opposition that Leibnizian optimism had encountered in France and Switzerland (principally through Castel and Crousaz) and the great support it had enjoyed in Germany, the last extended defences of it were made by French and Swiss authors. The first of these defences appeared in Emilie du Châtelet’s (1706–1749) Institutions de physique [Foundations of physics] (1740), the first chapters of which contain an outline of ‘the principal opinions of M. Leibniz on metaphysics’ which, she claims, were ‘drawn … from the works of the celebrated Wolff’ (du Châtelet 2009, 123). Certainly, some elements of her optimism are distinctly Wolffian. For example, du Châtelet echoes Wolff’s remarks in his Theologia naturalis when claiming that God’s choice of our world from an infinity of other possible worlds was a free one inasmuch he chose it because it pleased him the most (by virtue of containing more perfection than any other), and ‘to act following the choice of one’s own will is to be free’ (du Châtelet 2009, 143). However, other claims are more Leibnizian in tone, such as when du Châtelet characterizes the best possible world as ‘the one where the greatest variety exists with the greatest order, and where the largest number of effects is produced by the simplest laws’ (du Châtelet 2009, 144). In characterizing it thus, she appears to have borrowed from Leibniz’s ‘Principles of Nature and Grace,’ in which he states that the best possible plan for the universe is the one in which ‘there is the greatest variety together with the greatest order; … the greatest effect produced by the simplest ways’ (Leibniz 2014, 275). However, du Châtelet does not elaborate on her characterization of the best world, which leaves it unclear whether her reference to ‘the largest number of effects … produced by the simplest laws’ is an intentional revision of Leibniz’s ‘the greatest effect produced by the simplest ways,’ or a misunderstanding thereof.

A year after du Châtelet’s book there appeared in Switzerland an apology for a more obviously Leibnizian form of optimism in Défense du système leibnitien contre les objections et les imputations de Mr. de Crousaz [Defence of the Leibnizian System Against the Objections and Imputations of Mr de Crousaz] by Emer de Vattel (1714–1767), a Swiss jurist. Vattel explains that he was moved to write his apology for Leibniz because, although ‘Everyone now talks about the Leibnizian philosophy, yet few people have a proper idea of it; the majority know it only through the various writings for or against it that they have seen in the journals’ (Vattel 1741, preface, unnumbered page). By way of a corrective to this general level of ignorance, Vattel quotes huge chunks of the Theodicy and elaborates on them, as well as defending their principal ideas, though he does deviate on occasion. Most notably, he argues (1741, 39, §38) that Leibniz’s endorsement of eternal punishment for some conflicts with his optimism, and that to resolve the problem the doctrine of eternal punishment needs to be rejected in favour of Origenism, which takes pain and suffering to be purely medicinal in character and holds that through this medicine all creatures will eventually be saved. Vattel also inadvertently helped cement the association between Leibniz’s version of optimism and the more simplistic form outlined by Pope, which was often referred to under the rubric tout est bien. For when explaining the idea of the best world, Vattel argues that since each part is inseparable from the whole, and since God turns everything to a greater good, ‘we may conclude that ALL IS GOOD [TOUT EST BIEN] in relation to God’ (Vattel 1741, 49, §48).

It is worth noting that in the 1740s, Leibniz’s doctrine of the best world enjoyed belated support not just in France and Switzerland but also in Britain, where it was endorsed in a poem entitled The Pleasures of Imagination (1744), by the poet and physician Mark Akenside (1721–1770). When explaining how God came to choose our world, Akenside explains:

…from the wide complex
Of coexistent orders, one might rise,
One order, all-involving and intire.
He too beholding in the sacred light
Of his essential reason, all the shapes
Of swift contingence, all successive ties
Of action propagated thro’ the sum
Of possible existence, he at once,
Down the long series of eventful time,
So fix’d the dates of being, so dispos’d,
To every living soul of every kind
The field of motion and the hour of rest,
That all conspir’d to his supreme design,
To universal good: with full accord
Answering the mighty model he had chose,
The best and fairest of unnumber’d worlds
That lay from everlasting in the store
Of his divine conceptions (Akenside 1744, 63–65).

In a note, Akenside identifies ‘the vision at the end of the Theodicée of Leibnitz’ as one of his sources of inspiration for this passage, giving him the rare distinction of being a British thinker who supported Leibniz’s version of optimism rather than Pope’s (Akenside 1744, 64).

There were, as we shall see, a handful of later defences of optimism from the second half of the 1750s, at least in Germany, but to all intents and purposes the doctrine had ceased to attract any heavyweight support after the early 1740s. In the next section we shall see why.

VI. All Downhill from Here (1741–1753)

The last wave of spirited defences of optimism in the early 1740s made little impact. Vattel and Akenside’s work drew no comments, favourable or otherwise, while du Châtelet’s book fared little better. In the anonymous review in the Mémoires pour l’histoire des sciences & des beaux-arts just one paragraph is devoted to her endorsement of optimism, in which the reviewer simply notes the difficulty of harmonizing the system of optimism with the pure freedom of God ([Anon.] 1741, 907), thereby repeating an objection made by Castel in his 1737 review of the Theodicy in the same journal.

By this time, such breezy dismissals of optimism were not uncommon in either France or Britain. In the thousands of pages that comprised his multi-volume popular work Le spectacle de la nature [The Spectacle of Nature], Abbé Noël-Antoine Pluche (1688–1761) devoted a single paragraph to Leibniz’s doctrine of the best world, complaining that there is no way to compare our world with any others to establish that it is indeed the best (Pluche 1746, 155–156). In his 180+ page Apologie de la métaphysique [Apology for Metaphysics], David Bouiller (1699–1759), a Reformed pastor in Amsterdam, speedily dismissed the ‘Leibnizian’ principle tant mieux [so much the better] on the grounds that it undermines the moral order by removing the need to amend one’s inclinations or conduct (Bouiller 1753, 83–84). And the doctor of the Sorbonne Franc?ois Ilharat de La Chambre (1698–1753), over the course of three brutal pages in his Abregé de la philosophie [Abridgement of Philosophy], rattled off a list of objections to Leibniz’s optimism that were by now commonplace: that optimism destroys God’s freedom, that in any case a better world was possible (namely one without sin and pain), and that the world of today is not the same as the one God created in the beginning on account of it now containing sin and suffering following the fall (de la Chambre 1754, 287–289). Things were little better in Britain; the churchman and philosopher George Turnbull (1698–1748), a devotee of Popean rather than Leibnizian optimism, located Leibniz’s error ‘in his saying most unphilosophically, that God could not do otherwise than he hath done’ (Turnbull 1740, 38). And in a book which sought to defend Pope against Crousaz’s ‘misrepresentations,’ the churchman William Warburton (1698–1779) demolished Leibniz with a charge of fatalism in a single paragraph:

Plato said, God chose the best: Leibnitz said, he could not but chuse the best. Plato supposed Freedom in God, to chuse one of two Things equally good: Leibnitz contended that the Supposition was absurd; but however, admitting the Case, God could not chuse one of two Things equally good. Thus it appears the first contended for Freedom; and that the latter, notwithstanding the most artful Disguises in his Theodice, was a rank Fatalist (Warburton 1740, 18).15

Presumably, British and French detractors did not feel the need to offer more in-depth treatments of Leibnizian optimism because the doctrine had by then lost whatever loose hold it had had over their compatriots. This was not the case in Germany, however, and detractors there took optimism much more seriously, crafting thoughtful and sustained critiques. One such was to be found in a short book entitled De hoc mundo optimo non perfectissimo [On this best world that is not the most perfect] (1752), a youthful work by Georg Christian Croll (1728–1790), then a teacher (later professor) at the Zweibrücken grammar school. Croll’s book is notable for two reasons. First, he mentions Leibniz just once, in passing, while other optimists, in particular Wolff and Bilfinger, are discussed at length, thus indicating yet again that optimism was not always seen as a quintessentially Leibnizian doctrine, even in his native Germany. Second, Croll draws a distinction between the best world and the most perfect world, which till that point both optimists and non-optimists had assumed to be the same thing. Croll (1752, 15 and 18) argues that our world cannot be the most perfect because a more perfect one is possible, namely one without physical and moral evils, that is, one in which Adam did not fall. Yet Croll (1752, 18) insists that this does not mean our world is not the best; in fact, he supposes that it must be, inasmuch as God always wills the best and so must have decreed the creation of the best world. Our world is the best in the sense that it completely fulfils the end that God proposed to himself in creation, and it does so using the most perfect means at his disposal. As to what God’s end is, Croll does not say, though clearly it was not to create the most perfect world; for as he did not create that world it may be inferred that he did not want it (Croll 1752, 16).

A much more influential German critique appeared in the mid-1740s in the work of philosopher and Lutheran pastor Christian August Crusius (1715–1775), who by that time had already developed a reputation as a trenchant critic of Leibniz and Wolff. In his Entwurf der nothwendigen Vernunft-Wahrheiten, wiefern sie den zufälligen entgegen gesetzt werden [Outline of the Necessary Truths of Reason, Insofar as They Are Opposed to Contingent Truths] (1745), Crusius attacks Leibniz’s suggestion that ours is the best possible world on multiple fronts. He first dismisses the idea that there is such a thing as a best possible world: ‘such a best world, in which there would be all possible perfection, is impossible. For every world is necessarily finite; consequently its perfection is also finite, and God can constantly add even more to it through a progressive infinity’ (Crusius 1745, 743, §386). He claims that to insist a world could be infinite (and hence contain infinite perfection) is ‘absurd and contradictory’ (Crusius 1745, 744, §386), this being the preserve of God alone. Having undermined a key conceptual foundation of optimism, Crusius moves on to consider the doctrine’s argument structure, which he takes to be this:

If someone knows and wants the best, and is also capable of doing it, he will do the best. Now, since God, when he wanted to create a world, knew the best by virtue of his omniscience, was capable [of creating it] by virtue of his omnipotence, and wanted [to do so] by virtue of his wisdom, he necessarily created the best world (Crusius 1745, 748, §388).

He makes short shrift of the argument, noting that it presupposes there is such a thing as a best of all possible worlds, a presupposition he believes he has already shown to be unjustified (Crusius 1745, 748–749, §388). Not content with showing the conceptual incoherence of optimism and the weakness of its supporting argument, he carries on to argue that even if there were a best possible world, to suppose – as Leibniz does – that God could or would choose only that world is to destroy God’s freedom. He holds that to be truly free, a will must be entirely unrestricted in its operations, being ‘neither externally compelled nor internally necessitated’, and so have a genuinely open choice between available alternatives (Crusius 1744, 44, §38). Despite Leibniz’s attempts to finesse the issue, his notion of freedom, which sees God morally bound to choose the best, is rejected by Crusius as unsatisfactory precisely because it places severe restrictions on what God is able to choose (‘For what kind of choice is there where only a single action is possible?’) (Crusius 1745, 753, §388). Hence Leibniz’s doctrine must be rejected because it utterly destroys divine freedom. With optimism abandoned for all these reasons, Crusius is left to concede that ‘A world that God creates is therefore only very good’ (Crusius 1745, 753, §389).

VII. The Prize Essay Contest (1753–1755)

By the early 1750s, optimism had become something of a philosophical punching bag, even in Germany, site of its most fervent support in earlier decades. In the mid-1750s, the depth of the opposition that had formed against it became even more apparent thanks to the activities of the Royal Academy of Sciences and Belles-Lettres in Berlin, an institution that had been established by Leibniz in 1700 but had suffered from neglect and underinvestment until being revitalized in 1743 by Frederick the Great (1712–1786). Frederick’s reorganization brought in renowned figures such as Pierre-Louis Maupertuis (1698–1759), as perpetual president, and the mathematician Leonhard Euler (1707–1783); it also saw the approval of new statutes and funding, and the creation of an annual prize essay contest on a topic selected by the Academy’s members. In the 1740s and 1750s, the anti-Leibnizian faction of the Academy, led by Maupertuis and Euler, often used the prize contest to solicit (and reward) essays that were critical of Leibniz’s philosophy. In 1745 Leibniz’s doctrine of monads was chosen as the topic of the essay contest; in 1749 his determinism; and in 1753 it was decided that the focus of the contest of 1755 would be optimism. The official minutes of the Academy for 7 June 1753 record the decision:

The question proposed for the prize of 1755 was stated in these terms.

We request an examination of Pope’s system, contained in the proposition “All is good”.

It is a matter of: (1) determining the true meaning of that proposition according to the hypothesis of its author; (2) comparing it with the system of optimism, or the choice of the best, to indicate the connections and differences between them; (3) lastly, to put forward arguments that will be thought most fitting to confirm or destroy this system.16

Announcement of the contest prompted a number of complaints. Gottsched (1753) published a short tract against what he perceived to be the negative and trivializing tone of the Academy’s question, his concern even extending to the use of the term ‘optimism’, which he correctly noted had been invented as a term of abuse (though he mistakenly thought it had been invented by Crousaz). Another attack came from Lessing and Mendelssohn (1755), who ridiculed the juxtaposition of Pope and Leibniz in the Academy’s question, noting that the aims and approaches of the poet and philosopher were too different to warrant the sort of comparison the Academy proposed. Nevertheless, these concerns were not widely shared, judging from the number of entries the academy received: at least 18 (see Buschmann 1989, 199). Of these, it is notable that only one is known to have been sympathetic to optimism (namely [Künzli] 1755), this being a highly unoriginal piece containing little more than a statement of Leibniz’s own arguments for optimism and an account of his responses to objections. Despite its lack of novelty, this piece won the support of the Academy’s small Wolffian contingent, but was eventually awarded second place to appease Maupertuis, who had insisted the prize be given to an essay critical of Leibniz’s philosophy (see Winter 1957, 58). The prize was thus awarded to the essay by Adolf Friedrich Reinhard (1726–1783), chamber secretary to the Duke of Mecklenburg-Strelitz.

The first half of Reinhard’s essay is concerned to show that Pope and Leibniz taught the same doctrine (‘No difference; same mind, same ideas, same system’ (Reinhard 1755, 8)), though his methodology is somewhat questionable. Reinhard expounds Pope’s ideas at length, supporting his detailed exposition with numerous quotations from the poet while occasionally interjecting that Leibniz held precisely the same ideas, though Reinhard does not offer any textual evidence to support these claims (while he cites Pope frequently, he does not cite Leibniz at all). In this part of the essay, Reinhard demonstrates an impressive knowledge of Pope’s poem and an unfamiliarity with Leibniz that is equally noteworthy. In one of the more egregious examples, he states that on the principles of Leibniz’s optimism ‘it necessarily follows that God has created all possible substances’ (Reinhard 1755, 12).

The second half of Reinhard’s essay contains a critique of optimism, which consists of two main points. The first is directed at Leibniz’s claim that there is a single best possible world, which Reinhard dubs ‘the dogma of the unique greatest perfection’ (Reinhard 1755, 29), while the second is the oft-made objection that Leibniz’s doctrine strips God of free will. The first objection, which is unique to Reinhard, is worth outlining in some detail. In a novel move, he claims that the quantity of perfection is determined either by ‘the degree to which a being accomplishes a certain proposed end’ or by ‘the number and variety of ends that a thing is capable of obtaining’ (Reinhard 1755, 23–24). So stated, perfection is more a property of the range of available ends or the means used to attain them than a property of a thing or system of things. With that established, Reinhard supposes that an intelligent being’s primary end, or chief goal, is usually served by multiple secondary or tertiary ends, and that all of these ends can be attained in many different ways:

An intelligent being striving for perfection in its works can find, in the execution of the ends and rules it has proposed, several ways of acting that are equally in keeping with its intentions. These ways are consequently of equal perfection, and the intelligent being is indifferent about whether to choose one or the other (Reinhard 1755, 29).

Reinhard then slides from saying that there can be a number of equally good ways to attain any given end to saying that in fact there typically are, a slide he justifies on the basis of experience; there are, he notes, many different ways to build a pleasure house, by varying location, decor, arrangement etc., all of which are equally good and hence equivalent insofar as achieving the principal end (building a good pleasure house) is concerned. World-creation, he supposes, is no different, since in addition to the many different primary and secondary ends God could propose, there are likely many different ways of attaining each and every one of them and the optimist is in no position to deny that some of these will be just as good as others, leading to worlds of equal perfection (Reinhard 1755, 41). Hence there is no single best world and thus no requirement – moral or otherwise – for God to create one world in particular.

Reinhard’s critique prompted a number of responses,17 though curiously none pointed out that his definition of perfection was one of his own invention rather than one that any optimist actually accepted. Shortly after the announcement of the winning essay, André-Pierre Le Guay de Prémontval (1716–1764), who was on the voting committee for the prize essay, wrote to Reinhard to tell him that despite his misgivings about Reinhard’s essay he had voted for it anyway, neglecting to mention that in so doing he had bowed to pressure from Maupertuis.18 Nevertheless, Prémontval (1757, 75–136) also sent Reinhard a lengthy point-by-point rebuttal of the prize-winning essay and duly published it along with his letter.19 Publishing these pieces afforded Prémontval the opportunity to rehearse his own anti-Leibnizian cosmogony, first outlined in his Du hazard sous l’empire de la providence [On Chance under the Rule of Providence] (1755), which was published a few months before Reinhard’s essay was crowned by the Academy. In his book, Prémontval drew a sharp distinction between God’s choosing the best course and this being the best of all possible worlds, affirming the former but denying the latter. He agreed with Leibniz that, on account of God’s perfect nature, God would always choose the best course of action (Prémontval 2018, 120), and was even happy to suppose that God must thereby be necessitated, at least internally. But while Prémontval accepted that the world is the best as regards that which depends upon God, who ensures that the world contains as much perfection as possible at each moment, he held that it is not best as regards that which depends upon free beings, which routinely act in ways that despoil the world rather than enhance it (Prémontval 2018, 94).20

VIII. Post-Lisbon

If the aim in setting the 1755 prize question was to generate attacks on optimism, it succeeded, with the contest bringing a lot of the latent hostility towards optimism out into the open. By the time the Lisbon earthquake struck in November 1755, it was already open season on optimism in Germany just as it had been in France and Britain for some years beforehand. Contrary to what a number of scholars have claimed, the earthquake made little discernible impact on the debate about optimism, aside from Voltaire’s ‘Poème sur le déstruction de Lisbonne’ [Poem on the destruction of Lisbon] (1756),21 in which he complained that Leibniz had failed to explain why the best world had to contain evil, or at least evil that fell upon the innocent:

Leibnitz can’t tell me from what secret cause
In a world govern’d by the wisest laws,
Lasting disorders, woes that never end
With our vain pleasures real suff’rings blend;
Why ill the virtuous with the vicious shares?
Why neither good nor bad misfortunes spares? (Voltaire 1781, 57).

Voltaire’s poem did, however, earn a robust response from the Swiss philosopher Jean-Jacques Rousseau (1712–1778), who informed the Frenchman ‘This optimism which you find so cruel yet consoles me amid the very pains which you depict as unbearable’ (Rousseau 1997, 233). Quite what form of optimism Rousseau cleaved to is unclear, however. At times it seems quite Leibnizian, such as when he states:

Instead of saying All is well, it might be preferable to say The whole is good or All is good for the whole. Then it is quite obvious that no human being could give direct proofs pro or con; for these proofs depend on a perfect knowledge of the world’s constitution and of its Author’s purposes, and this knowledge is indisputably beyond human intelligence (Rousseau 1997, 240).

Yet some of Rousseau’s claims are much less obviously Leibnizian in tenor, such as when he puts the blame for many of Lisbon’s human casualties on the house builders (for erecting multi-storey houses) and the victims themselves (for choosing to run into burning houses to save their possessions) (Rousseau 1997, 234).

As atypical as some of Rousseau’s claims were, his deviation from Leibniz’s own doctrine was itself far from atypical. Indeed, in the 1750s, the few who were still prepared to defend optimism did not defend a recognizably Leibnizian form of it, although they deviated from it in their own idiosyncratic ways. In 1756, for example, the Benedictine monk Cölestin Schirmann (1724–1793) published his dissertation, De mundo optimo libertati, potentiae, et sapientiae dei convenientissimo [On the Best World, Most Agreeable to the Freedom, Power, and Wisdom of God] in which he defended a recognizably Wolffian notion of the best world without mentioning either Wolff or Leibniz once over the course of 200 pages. Instead, he littered his book with citations of Aquinas, making it appear as though the Angelic Doctor had given his blessing to the Wolffian doctrine of the best world. A year later, Johannes Christian Förster published his dissertation, Notio et demonstratio doctrinae de mundo optimo [Examination and Demonstration of the Doctrine of the Best World] (1757), in which he rehearsed Wolff’s doctrine of the best world, albeit with the occasional innovation (or misunderstanding), such as his claim that ‘the best world requires the best parts’ (Förster 1757, xxxiv), namely ‘the most perfect substances’ (Förster 1757, xvii), which rather suggests that the best world would be composed of angels or minor deities rather than human beings and animals.

While the remaining supporters of optimism cleaved to forms of it that differed from Leibniz’s own in significant ways, opponents sometimes attacked forms of optimism that no optimist had upheld. For example, in his De l’origine du mal [On the Origin of Evil] (1758), Viscount Pierre-Alexandre d’Alès de Corbet (1715–1770?) insisted that optimism places limits on God’s omnipotence, for insofar as it entails that ‘he [God] has created all possible beings… he cannot add any to them, nor remove any from them, nor overturn the universe’ (d’Alès 1758, I: 154). D’Alès identified the key proponents of optimism as Leibniz, d’Houteville, Wolff, and du Châtelet (d’Alès 1758, I: 142), none of whom had held or even implied that God had created all possible beings.

Despite his shaky grasp of optimism, D’Alès did at least take it seriously enough to develop his critique over twenty pages or so. Others were far more dismissive, supposing that the doctrine was so obviously flawed that it could be rejected in a handful of sentences. In 1760, for example, Georg Ludwig von Bar (1701–1767), a poet and literary critic, argued that Leibniz’s concerted efforts to bring about reform in theology, philosophy, and language demonstrated that he clearly ‘did not find all universally good in the best of imaginable worlds’ (1760, 99), with similar barbs levelled against Pope and Wolff. A few years later, the Jesuit mathematician-physicist François Para Du Phanjas (1724–1797) argued that a simple thought-experiment would refute Leibniz’s optimism: just conceive the same world, the same laws, and the same human race but without the majority of evils and it is clear that this world could be more perfect (or less imperfect) than it actually is (Du Phanjas 1767, 149). Equally dismissive was the Catholic theologian Nicolas Bergier (1718–1790), who needed just two sentences to refute optimism in his Examen du matérialisme [Examination of Materialism]:

The system of optimism is false in that it supposes this world is the best and most perfect that God could produce: this is to needlessly limit divine power. If God was not able to create a world in which there were more goods and fewer evils he is not infinitely powerful (Bergier 1771, 257).

Over the course of the 1760s and 1770s, many of the same objections that had been levelled against optimism earlier in the century were repeated, but opponents continued to develop new objections, especially in Britain. In his An Essay on the Future Life of Brutes, Richard Dean (1726/7–1778), a curate of Middleton near Manchester, advanced a number of concerns against Leibniz’s doctrine. He complained that the very idea of possible worlds with complete histories was unsustainable, since it was absurd to suppose that there was any fact of the matter about the free actions of human beings until they actually happened (Dean 1767, I: 40–41). He complained also that it was implausible to think that evils render the world more perfect (Dean 1767, I: 50–51), even if they do sometimes have their uses (for example by inspiring us to avoid sin and practise piety and virtue). This latter point was echoed by James Rothwell (1723–1798), master of Blackrod grammar school, who granted that Leibniz was right to say that ‘The method which God pursues in every thing he does, is certainly the best’, but insisted that ‘Leibnitz loses himself, when he asserts that the world is more excellent on account of evils’, while allowing, like Dean, that ‘natural evils have their use’ (Rothwell 1769, 27).

It would be possible to multiply examples of reactions to optimism in the second half of the eighteenth century, but to do so would yield ever-diminishing returns, merely confirming the pattern we have already seen, namely that of infrequent support and rampant attacks (often casually dismissive) from opponents. It is sufficient to note that, of the opponents discussed in this section, all of whom published after 1755, it was only Voltaire who mentioned the Lisbon earthquake in connection with optimism.

IX. The Caricature of Optimism

On the basis of our survey, it should be clear that the fate of Leibnizian optimism was not decided by the Lisbon earthquake, an event which did not even represent a turning point in the fortunes of the doctrine. As we have seen, support for optimism was waning from the early 1740s onwards, and what support there was after that was typically found in the dissertations of university students or in the reprints of works originally published in the 1730s, such as Baumgarten’s Metaphysica and Gottsched’s Erste Grunde der gesammten Weltweisheit. Moreover, there was a great deal of vocal opposition to optimism in the first half of the eighteenth century, especially from the 1730s onwards. And it is surely worthy of note that opposition to optimism, both before and after the Lisbon earthquake, was usually philosophical and theological in nature, with Voltaire alone seeking to reject it on account of its inconsistency with events in Portugal (if indeed that is what he was doing). On the basis of this, the most plausible conclusion to draw is that optimism was levelled philosophically and theologically rather than seismically.

We may also draw two further conclusions. First, eighteenth-century supporters of optimism often did not endorse Leibniz’s own particular brand of the doctrine, either because they did not fully understand it or because they deliberately modified it. Second, many eighteenth-century opponents of Leibnizian optimism did not fully understand the doctrine they opposed. Indeed, some opponents had such a slender grasp of Leibnizian optimism that they unwittingly presented something that verged on a caricature of it. In fact, this problem ran much deeper than is apparent from the thinkers we have discussed thus far. It was also a problem that did not go unnoticed in the eighteenth century. Samuel Formey asked ‘How many adversaries have risen up against Leibniz’s best world and Wolff’s chain of things without having understood what these philosophers meant by that, and by attributing ideas to them which they never cease to disown?’ (Formey 1741, 105). Such ignorance of key details of Leibniz’s doctrine resulted in a number of caricatures of it that were every bit as grotesque as that which Voltaire would draw in Candide. In 1746, Abbé Pluche misconstrued Leibniz’s claim that ours is the best possible world as a claim about our planet rather than about our universe:

The partisans of Leibniz, the optimists … decide, against Plato, that all is good and even for the best; that man is such as he should be, and that from this motley assortment of states, inclinations, and actions, both bad and good, there results a variety of arrangements which delight God and enrich the universe in his eyes, by putting in our abode a constitution different from that of the other planets. From this sublime comparison of our planet with the other worlds, of which they [sc. the optimists] certainly have no reports or information, they derive the so-called principles of our morality and the motives of our tranquillity (Pluche 1746, 155–156).

Thirty years later, Pierre-Louis-Claude Gin would make a similar mistake in his own examination of Leibniz’s optimism: ‘By what right do we make ourselves the centre of the universe? Why would this small globe we inhabit be the best of the infinite worlds of which the universe is composed?’ (Gin 1778, 129). Betraying just as little grasp of the Theodicy, de La Chambre insisted that, ‘According to Mr Leibniz, there is no evil in the world’ (de La Chambre 1754, 286). But if there was a prize for the most egregious misrepresentation of Leibniz’s view, it would undoubtedly have been awarded to David Hume (1711–1776). In dialogue 10 of his Dialogues concerning Natural Religion (1751/1779), Hume has the character Philo stress the sheer scale of human misery; when the character Demea asks whether anyone had been so extravagant as to deny human misery, Hume has Philo respond: ‘Leibniz has denied it; and is perhaps the first who ventured upon so bold and paradoxical an opinion;22 at least, the first, who made it essential to his philosophical system’ (Hume 2007, 69).23 Given how often and how acutely Leibniz’s doctrine of the best world was misunderstood, it is difficult to escape the thought that its fate was decided more by unintended parodies than by its own internal flaws.24


1Unless otherwise stated, all translations in this paper are my own. 

3See Leibniz 1989, 39. It should be noted that the Discourse on Metaphysics has been interpreted in completely different ways on this matter. For example, Rescher (1981, 4) argues that it says variety and simplicity are in conflict and so God must seek the optimal trade-off of the two, while Wilson (1983, 775–6) argues that it says variety and simplicity are simultaneously maximized in the best world. I have sided with the latter view; see Strickland (2006, 72). 

4Although Knoerr and Budde do not indicate the source of their lexical argument, it can be found in the work of language specialist Matthias Wasmuth (1625–1688). See Wasmuth 1691, 35. 

6In the eighteenth century this work was often referred to as the German Metaphysics, as is the case now. 

7Although Leibniz did not present his work this way, Hansch claims that ‘None of the things in these demonstrations are my own, they are all Leibniz’s’ (Hansch 1728, preface, unnumbered page). 

8There are texts in which Leibniz endorses the great chain of being also (e.g. Leibniz 1906, II: 558–559; Leibniz 1996, 473), though as these were not published until much later they would not have been available to Pope. 

9This passage is not in the first edition of 1733. 

10The translation follows the fourth edition of Baumgarten’s work, from 1757. 

11Baumgarten defines a universal nexus as ‘one that is among each and every thing’ (Baumgarten 2011, 109, §48). 

13The term ‘optimism’ would later be defined in a disparaging way in the Dictionnaire de Trévoux of 1752 and 1771, where it is described as a ‘didactic term … given to the system of those who claim that all is good, that the world is the best that God could create, that the best possible is found in everything that exists and happens. Even crimes are accessories to the beauty and perfection of the moral world, since goods result therefrom. The crime of Tarquin, who violated Lucretia, produced the freedom of Rome and consequently all the virtues of the Roman republic. See Mr Leibniz’s Theodicy. But in the best of worlds, why does it have to be that virtues are produced by crimes? Besides, optimism determines God like an automaton. How is this opinion harmonized with his freedom? It seems that it is only a disguised materialism, a spiritual Spinozism’ (Dictionnaire de Trévoux VI: 359). 

14Leibniz had in fact tried unsuccessfully to have the Theodicy translated into English, indicating in 1715 that his first choice of translator would be the editor of the Memoirs of Literature, Michel de la Roche (c. 1680–1742), with the theologian and linguist William Wotton (1666–1727) as a possible alternative. Samuel Clarke (1675–1729) was also mooted for the role, but Leibniz was not comfortable with the idea since Clarke was a known associate and sympathiser of Isaac Newton (1643–1727), with whom Leibniz was in dispute at the time over the invention of the calculus. For more information on Leibniz’s efforts to have the Theodicy translated into English, see Strickland 2016, 72 and 79–80. 

15The same passage, with a few minor differences in phrasing, is also to be found in Warburton 1742, 26. 

16From the register for 7 June 1753 held by the Archiv der Berlin-Brandenburgischen Akademie der Wissenschaften under the shelfmark I IV 31/06, Bl. 48. 

17See for example Formey 1756, 29–32, and Kant 1992. 

18‘Know, then, that with the votes equal between your piece and another, I – as much a supporter of optimism as I am – twice tipped the scales on your side’ (Prémontval 1757, 69). The other piece Prémontval refers to here is likely the pro-optimism essay ([Künzli], 1755). Prémontval’s claim to be a supporter of optimism was somewhat disingenuous, as we shall see. 

19Both pieces were subsequently republished in German translation along with a number of other pieces prompted by Reinhard’s winning essay; see Ziegra 1759. 

20Despite Prémontval’s vocal opposition to Leibniz and his rejection of Leibnizian optimism, he has sometimes been incorrectly pegged as endorsing an optimism not dissimilar to Leibniz’s own. See Barber 1955, 168. 

21The poem’s subtitle – ‘Examination of this axiom: all is good’ – is likely an allusion to the Academy’s prize question. 

22Such a remark suggests Hume had not read the Theodicy, which in part seeks to show how the world can be the best in spite of human misery, and that therefore he had second-hand acquaintance of Leibniz’s doctrine at best. Possibly the source of Hume’s misunderstanding was one of Edmund Law’s annotations on King’s De origine mali, in which Law states that ‘I believe that there’s no Evil in Life but what is very tolerable’ before referring the reader to the Theodicy as containing a proof that the good of this world exceeds the evil (see King 1739, 475 note). However, Hume clearly goes well beyond that in attributing to Leibniz the denial of human misery. 

23Nor ought we to suppose that such caricatures are confined to the eighteenth century, as a number of recent thinkers have claimed that Leibniz denied the existence of evil (see Griffin 2004, 131 and 135; van Inwagen 2006, 60–61; Dombrowski 2016, 65–66). 

24I would like to thank Daniel J. Cook, Nicholas Jolley, Julia Weckend, and two anonymous reviewers for helpful feedback on an earlier version of this paper. A shortened version of this paper was also read at the University of Liverpool on 11 October 2018 and attracted insightful comments from the staff and students in attendance. Their remarks were greatly appreciated. 

Competing Interests

The author has no competing interests to declare.


  1. Akenside, Mark. The Pleasures of Imagination. A Poem. In Three Books. London: R. Dodsley, 1744. 

  2. [Anon.]. “Essais de Theodicée.” Mémoires pour l’histoire des sciences & des beaux-arts (1713), 1178–1199. 

  3. [Anon.]. “Essais de Theodicée.” Nouvelles de la Republique des lettres (1710b), 314–342 and 363–396. 

  4. [Anon.]. “Essais de Theodicée.” Unschuldige Nachrichten (1710a), 405–410. 

  5. [Anon.]. “Institutions de physique.” Mémoires pour l’histoire des sciences & des beaux-arts (1741), 894–927. 

  6. Barber, W. H. Leibniz in France from Arnauld to Voltaire. Oxford: Clarendon Press, 1955. 

  7. Baumgarten, Alexander. Metaphysics. Edited and translated by Courtney D. Fugate and John Hymers. London: Bloomsbury, 2011. 

  8. Bergier, Nicolas. Examen du matérialisme: ou Réfutation du système de la nature. Tome second. Paris: Humblot, 1771. 

  9. Bilfinger, Georg Bernhard. De origine et permissione mali, praecipue moralis, commentatio philosophica. Frankfurt and Leipzig: Theodore Mezler, 1724. 

  10. Bouiller, David Renauld. Apologie de la métaphysique: à l’occasion du discours préliminaire de l’encyclopedie. Amsterdam: Jean Catuffe, 1753. 

  11. Buschmann, Cornelia. “Die Philosophischen Preisfragen und Preisschriften der Berliner Akademie der Wissenschaften im 18. Jahrhundert.” In Aufklärung in Berlin, edited by Wolfgang Förster, 165–228. Berlin: Akademie-Verlag, 1989. 

  12. Castel, Louis-Bertrand. “Essais de Théodicée.” Mémoires pour l’histoire des sciences & des beaux-arts (1737), 5–36, 197–241, and 444–71. 

  13. Croll, Georg Christian. De hoc mundo optimo non perfectissimo. Zweibrücken: Hallanzy, 1752. 

  14. Crousaz, Jean Pierre de. Examen de l’essay du Monsieur Pope sur l’homme. Lausanne: Bousquet, 1737. 

  15. Crousaz, Jean Pierre de. Commentaire sur la traduction en vers, de Mr. l’Abbé du Resnel, de l’Essai de M. Pope sur l’homme. Geneva: Pellissari, 1738. 

  16. Crusius, Christian August. Anweisung vernünftig zu leben, Darinnen nach Erklärung der Natur des menschlichen Willens die natürlichen Pflichten und allgemeinen Klugheitslehren im richtigen Zusammenhange vorgetragen werden. Leipzig: Gleditsch, 1744. 

  17. Crusius, Christian August. Entwurf der nothwendigen Vernunft-Wahrheiten, wiefern sie den zufälligen entgegen gesetzt werden. Leipzig: Gleditsch, 1745. 

  18. d’Alès, Viscount. De l’origine du mal, ou examen des principales difficultés de Bayle, sur cette matiere, &c. 2 vols. Paris: Duschesne, 1758. 

  19. de la Chambre, Franc̨ois Ilharat. Abregé de la philosophie, ou Dissertations sur la certitude humaine, la logique, la métaphysique, et la morale. Tome premier. Paris: Delaguette, 1754. 

  20. de la Roche, Michel. “Essais de Theodicee.” Memoirs of Literature (1711), 237–239, 241–243, 257–259, and 261–263. 

  21. de Vattel, Emer. Défense du système leibnitien contre les objections et les imputations de Mr. de Crousaz, contenues dans l’Examen de l’Essai sur l’homme de Mr Pope. Leiden: Jean Luzac, 1741. 

  22. Dean, Richard. An Essay on the Future Life of Brutes. 2 vols. Manchester: J. Harrop, 1767. 

  23. Dictionnaire universel françois et latin, vulgairement appelé Dictionnaire de Trévoux. 8 vols. New ed. Paris: Compagnie des libraires associés, 1771. 

  24. Dombrowski, Daniel A. A History of the Concept of God. New York: State University of New York Press, 2016. 

  25. du Châtelet, Emilie. Selected Philosophical and Scientific Writings. Edited by Judith P. Zinsser. Translated by Isabelle Bour and Judith P. Zinsser. Chicago: University of Chicago Press, 2009. DOI: 

  26. Dudgeon, William. A View of the Necessitarian or Best Scheme: Freed From the Objections of M. Crousaz, in His Examination of Mr. Pope’s Essay on Man. London: T. Cooper, 1739. 

  27. Du Pont-Bertris. Éloges et caractères des philosophes les plus célèbres: depuis la naissance de Jésus-Christ, jusqu’à présent. Paris: Henry-Simon-Pierre Gissey, 1726. 

  28. Fonnesu, Luca. “Der optimismus und seine Kritiker in Zeitalter der Aufklärung.” Studia Leibnitiana 26 no. 2 (1994), 131–162. 

  29. Formey, Samuel. “Dissertation qui a remporté le prix proposé par l’Académie Royale des Sciences & Belles-Lettres de Prusse, sur L’OPTIMISME.” Nouvelle bibliothèque germanique 18 (1756), 22–32. 

  30. Formey, Samuel. La Belle Wolffienne. The Hague: Charles le Vier, 1741. 

  31. Förster, Johannes Christian. Notio et demonstratio doctrinae de mundo optimo. Halle: Grunertian, 1757. 

  32. Gin, Pierre-Louis-Claude. De la religion, par un homme du monde; seconde partie. Paris: Moutard, 1778. 

  33. Gottsched, Johann Christoph. De optimismi macula diserte nuper Alexandro Popio anglo, tacite autem G. G. Leibnitio, perperam licet, inusta. Leipzig: Breitkopf, 1753. 

  34. Gottsched, Johann Christoph. Erste Grunde der gesammten Weltweisheit. 2nd ed. Leipzig: Breitkopf, 1735. 

  35. Griffin, David Ray. God, Power, and Evil. Louisville: Westminster John Knox Press, 2004. 

  36. Hahn, Immanuel Ernst. De bonitate mundi biblica. Wittenberg: Eichsfeld, 1737. 

  37. Hansch, Michael Gottlieb. Godefridi Guilielmi Leibniti, principia philosophiae, more geometrico demonstrata: cum excerptis ex epistolis philosophi et scholius quibusdam ex historia philosophica. Frankfurt and Leipzig: Monath, 1728. 

  38. Houtteville, Claude François Alexandre. Essai philosophique sur la providence. Paris: Gregoire Dupuis, 1728. 

  39. Hume, David. Dialogues concerning Natural Religion and Other Writings. Edited by Dorothy Coleman. Cambridge: Cambridge University Press, 2007. 

  40. Kant, Immanuel. Theoretical Philosophy, 1755–1770. Edited and translated by David Walford and Ralf Meerbote. Cambridge: Cambridge University Press, 1992. 

  41. King, William. An Essay on the Origin of Evil. Edited and translated by Edmund Law. 3rd ed. Cambridge: William Thurlbourn, 1739. 

  42. King, William. De origine mali. London: Benjamin Tooke, 1702. 

  43. Knoerr, Georg Christian and Johann Franz Budde. Doctrinae orthodoxae de origine mali contra recentiorum quorundam hypotheses modesta assertio. Jena: Müller, 1712. 

  44. Künzli, Martin. “Discours sur cette question, tout est-il bien? proposée par l’Académie Royale des Sciences et Belles Lettres de Berlin, pour le prix de l’année 1755.” In Dissertation qui a remporté le prix proposé par l’Académie Royale des Sciences et Belles Lettres de Prusse, sur l’optimisme, avec les pieces qui ont concouru, 1–31. Berlin: Haude and Spener, 1755. 

  45. Leibniz, Gottfried Wilhelm. Confessio Philosophi: Papers Concerning the Problem of Evil, 1671–1678. Edited and translated by Robert C. Sleigh, Jr. New Haven: Yale University Press, 2005. 

  46. Leibniz, Gottfried Wilhelm. Hauptschriften zur Grundlegung der Philosophie. Edited by Artur Buchenau. 2 volumes. Hamburg: Verlag von Felix Meiner, 1906. 

  47. Leibniz, Gottfried Wilhelm. Lehr-Sätze über die Monadologie: ingleichen von Gott und seiner Existentz, seinen Eigenschaften und von der Seele des Menschen. Frankfurt and Leipzig: Johann Meyer, 1720. 

  48. Leibniz, Gottfried Wilhelm. Leibniz’s Monadology: A New Translation and Guide. Edited and translated by Lloyd Strickland. Edinburgh: Edinburgh University Press, 2014. 

  49. Leibniz, Gottfried Wilhelm. New Essays on Human Understanding. Edited and translated by Jonathan Bennett and Peter Remnant. 2nd edition. Cambridge: Cambridge University Press, 1996. DOI: 

  50. Leibniz, Gottfried Wilhelm. Philosophical Essays. Edited and translated by Roger Ariew and Daniel Garber. Indianapolis: Hackett, 1989. 

  51. Leibniz, Gottfried Wilhelm. “Principes de la nature & de la grace, fondez en raison.” L’Europe savante. Novembre M.DCC.XVIII. Tome sixieme. Premiere partie, 101–123. The Hague: A. de Rogissart, 1718. 

  52. Leibniz, Gottfried Wilhelm. Theodicy. Edited by Austin Farrer. Translated by E. M. Huggard. Chicago: Open Court, 1985. 

  53. Lessing, Gotthold Ephraim and Moses Mendelssohn. Pope—ein Metaphysiker! Danzig: Johann Christian Schuster, 1755. 

  54. Lütgert, Wilhelm. “Die Erschütterung des Optimismus durch das Erdbeben von Lissabon 1755.” In Beiträge zur förderung christlicher Theologie, edited by D. A. Schlatter and D. H. Cremer, 1–41. Gutersloh: Bertelsmann, 1901. 

  55. Malebranche, Nicolas. Treatise on Nature and Grace. Edited and translated by Patrick Riley. Oxford: Clarendon Press, 1992. 

  56. Moltmann, Jürgen. “Theodicy.” In A New Dictionary of Christian Theology, edited by Alan Richardson and John Bowden, 564–566. London: SCM Press, 1983. 

  57. Paice, Edward. Wrath of God: The Great Lisbon Earthquake of 1755. London: Bloomsbury, 2008. 

  58. Phanjas, François Para Du. Éléments de métaphysique sacrée et profane, ou Théorie des êtres insensibles. Paris: Jombert, 1767. 

  59. Pluche, Antoine. Le spectacle de la nature, ou entretiens sur les particularités de l’histoire naturelle, tome sixième. Paris: Estienne, 1746. 

  60. Pope, Alexander. An Essay on Man. Part 1. London: J. Wilford, 1733. 

  61. Pope, Alexander. The Correspondence of Alexander Pope. Edited by George Sherburn. 5 vols. Oxford: Clarendon Press, 1956. 

  62. Prémontval, André-Pierre Le Guay de. The Philosophical Writings of Prémontval. Edited and translated by Lloyd Strickland. Lanham, MD: Lexington, 2018. 

  63. Prémontval, André-Pierre Le Guay de. Vues Philosophiques; ou protestations et declarations sur les principaux objets des connoissances humaines, 2 vols. Berlin: Joachim Pauli, 1757. 

  64. Reinhard, Adolph Friedrich. Le système de Mr Pope sur la perfection du monde, comparé à celui de Mr de Leibnitz, avec un examen de l’optimisme. Berlin: Haude and Spener, 1755. 

  65. Rescher, Nicholas. Leibniz’s Metaphysics of Nature. Dordrecht: D. Reidel, 1981. DOI: 

  66. Rothwell, James. A Letter to the Rev. Mr. Dean, of Middleton; Occasioned by Reading his Essay on the Future Life of Brute Creatures. n.p.: n.p., 1769. 

  67. Rousseau, Jean-Jacques. The Discourses and Other Political Writings. Edited and translated by V. Gourevitch. Cambridge: Cambridge University Press, 1997. 

  68. Saine, Thomas P. The Problem of Being Modern, Or, The German Pursuit of Enlightenment from Leibniz to the French Revolution. Detroit: Wayne State University Press, 1997. 

  69. Schirmann, Cölestin. De mundo optimo libertati, potentiae, et sapientiae dei convenientissimo. Styrae: Menhardt, 1756. 

  70. Strickland, Lloyd. Leibniz Reinterpreted. London: Bloomsbury, 2006. 

  71. Strickland, Lloyd. “The reception of the Theodicy in England.” In Leibniz, Caroline und die Folgen der englischen Sukzession, 69–90. Edited by Wenchao Li. Stuttgart: Franz Steiner Verlag, 2016. 

  72. Turnbull, George. Christian Philosophy: or, the Christian Doctrine concerning God, Providence, Virtue, and a Future State, Proved to be Agreeable to True Philosophy. London: J. Noon, 1740. 

  73. Utinus, Almonius Johann Christoph Harenberg. “Demonstratio theologico-philosophica, quod idea electi mundi optimi a Deo, salva ejus sapientia & libertate, removeri nequeat.” In Bibliotheca Historico-Philologico-Theologica. Classis octavae fasciculus primus, 47–78. Bremen: Hermann Brauer, 1725. 

  74. van Inwagen, Peter. The Problem of Evil. Oxford: Oxford University Press, 2006. DOI: 

  75. Voltaire. Oeuvres complètes de Voltaire. Tome douzième. Kehl: La Société littéraire typographique, 1784. 

  76. Voltaire. The Works of M. de Voltaire. Translated from the French. Volume XXXIII. Edited and translated by T. Smollett and others. New edition. London: S. Crowder, 1781. 

  77. von Bar, Georg Ludwig. Babioles littéraires & critiques en prose et en vers. Hamburg: Jean Charles Bohn, 1760. 

  78. Warburton, William. A Critical and Philosophical Commentary on Mr. Pope’s Essay on Man. London: John and Paul Knapton, 1742. 

  79. Warburton, William. A Vindication of Mr. Pope’s Essay on Man, from the Misrepresentations of Mr de Crousaz. London: J. Robinson, 1740. 

  80. Wasmuth, Matthias. Grammatica Ebraeae Linguae Wasmuthiana. Leipzig: Lanckisch, 1691. 

  81. Weinrich, Harald. “Literatur eines Weltereignisses: das Erdbeben von Lissabon.” In Literatur für Leser, edited by Harald Weinrich, 64–76. Stuttgart: Kohlhammer, 1971. 

  82. Wilson, Catherine. “Leibnizian Optimism.” Journal of Philosophy 80 no. 11 (1983), 765–783. DOI: 

  83. Winter, Eduard. Die Registres der Berliner Akademie der Wissenschaften 1746–1766. Berlin: Akademie Verlag, 1957. 

  84. Wolff, Christian. “Tentamen theodiceae.” Acta Eruditorum (1711), 110–121 and 159–168. 

  85. Wolff, Christian. Theologia naturalis, methodo scientifica pertractata. Pars posterior, qua existentia et attributa dei ex notione entis perfectissimi et natura animae demonstrantur, et atheismi, deismi, fatalismi, naturalismi, spinosismi aliorumque de deo errorum fundamenta subvertuntur. Frankfurt and Leipzig: n.p., 1737. 

  86. Wolff, Christian. Theologia naturalis, methodo scientifica pertractata. Pars prior, integrum systema complectens, qua existentia et attributa dei a posteriori demonstrantur. Frankfurt and Leipzig: n.p., 1736. 

  87. Wolff, Christian. Vernünfftige Gedancken von Gott, der Welt und der Seele des Menschen, auch alien Dingen überhaupt, den Liebhabern der Wahrheit mitgetheilet. Halle: Renger, 1720. 

  88. Ziegra, Christian. Sammlung der Streitschriften über die Lehre von der besten Welt, und verschiedene damit verknüpfte wichtige Wahrheiten, welche zwischen dem Verfasser der im Jahr 1755. von der Akademie zu Berlin gekrönten Schrift vom Optimismo, und einigen berühmten Gelehrten gewechselt worden. Rostock and Wismar: Berger and Boedner, 1759.