Gottfried Wilhelm Leibniz's Essais de Theodicee sur la bonte de Dieu, la liberte de l'homme et l'origine du mal (Essays on Theodicy: on the Goodness of God, the Freedom of Man, and the Origin of Evil), published in 1710, coined the word 'theodicy' and constituted the most systematic Enlightenment attempt to reconcile the existence of evil with belief in a good and omnipotent God. Leibniz drew extensively on the biblical narrative of creation and on Pauline theology to argue that this is the best possible world - that God, being perfectly rational and perfectly good, necessarily chose from all possible worlds the one containing the greatest possible balance of perfection. Voltaire's savage satirical response in Candide (1759), written after the Lisbon earthquake of 1755 killed tens of thousands, made 'the best of all possible worlds' a philosophical shorthand for dangerous optimism. The debate between Leibniz and his critics remains one of the most important in the philosophy of religion.
The Thinker and His Work
Leibniz (1646-1716) was the co-inventor of calculus (independently of Newton), the developer of the binary number system, the designer of a mechanical calculator, a diplomat, a historian, and arguably the last person who knew all the knowledge of his era. The Theodicy, his only book-length philosophical work published during his lifetime, was written in French for a general educated audience and is more accessible than his technical philosophical writings. It emerged from conversations with Queen Sophia Charlotte of Prussia, who had challenged Leibniz to respond to the skeptical arguments of Pierre Bayle, particularly Bayle's claim in the Historical and Critical Dictionary that evil provides an insuperable objection to rational theism.
Biblical Texts Engaged
Romans 9:20 - 'But who are you, O man, to answer back to God? Will what is molded say to its molder, "Why have you made me like this?"' - is Paul's response to the implied objection against divine election, and Leibniz uses it as a model for the proper human posture before the mystery of divine governance. The clay-potter image acknowledges that God's ways are not always transparent to human reason, but Leibniz does not rest there - he argues that reason can in fact vindicate God's choices, that the best possible world defense is rationally coherent.
Genesis 1:31 - 'And God saw everything that he had made, and behold, it was very good' - is the biblical affirmation of creation's goodness that Leibniz takes as his starting point. If God declared creation very good, then whatever evils exist within it must be compatible with this judgment. Leibniz distinguishes three kinds of evil - metaphysical evil (imperfection, finitude, the limitation of any created being), physical evil (suffering, pain), and moral evil (sin) - and argues that all three are permitted by God because a world without them would be a worse world overall.
Romans 8:28 - 'And we know that for those who love God all things work together for good, for those who are called according to his purpose' - provides the Pauline warrant for the providential claim that apparent evils serve the greater good. Leibniz reads this verse as a theological statement of the principle he is trying to demonstrate philosophically.
Core Argument
Leibniz's argument proceeds from his metaphysics of possible worlds. God, as the perfectly rational creator, surveyed all possible worlds before creation - all internally consistent configurations of reality - and chose the one with the greatest perfection. Perfection is measured by the greatest variety of phenomena produced by the simplest laws, the greatest amount of virtue and happiness compatible with the structure of reality, and the greatest overall harmony.
Evil is permitted in the best possible world because its elimination would require creating a less perfect world. Moral evil (sin) is permitted because genuine freedom - which is itself a great good, and whose exercise is necessary for genuine virtue - includes the possibility of choosing evil. Physical evil (suffering) is permitted partly as the consequence of moral evil, partly as the means of moral development, and partly because a world of greater perfection overall requires some suffering as the price of its structure. Metaphysical evil (finite imperfection) is simply the necessary condition of anything being created at all; God alone is infinite and perfect, and any creature is by definition limited.
Intellectual Context
Leibniz was writing against the background of seventeenth-century debates about God's relationship to evil, particularly the debate about Descartes's account of God as the creator of eternal truths (which seemed to make morality arbitrary) and the debates within Catholicism between Jansenists (who emphasized God's absolute sovereignty and human depravity) and Jesuits (who emphasized human freedom and divine condescension). His Theodicy attempts to chart a middle course: God is sovereign, creation is genuinely good, human freedom is real, and evil is a permitted by-product of the best possible arrangement.
Reception and Critique
Voltaire's Candide (1759) is the most devastating literary response to Leibnizian optimism. The novel's catalogue of catastrophes - the Lisbon earthquake, the Inquisition, war, slavery - is presented as a satirical refutation of the claim that this is the best possible world. 'If this is the best possible world, what are the others like?' The earthquake of 1755, which killed between 30,000 and 60,000 people and destroyed one of Europe's most prosperous cities on All Saints' Day while the churches were full, crystallized philosophical doubt about providential optimism in a way that pure argument could not.
Kant's early essay on the problem of evil and his later essay 'On the Failure of All Philosophical Attempts at Theodicy' (1791) argued that Leibniz's project was misconceived: human reason cannot access the divine perspective from which the overall balance sheet of creation would be visible. Any theodicy that claims to justify God from the human standpoint is guilty of presumption.
In contemporary philosophy, Alvin Plantinga's free will defense agrees with Leibniz that moral evil is compatible with divine goodness (because genuine freedom requires the possibility of evil), but rejects the strongest Leibnizian claim that this is the best possible world - arguing instead for the more modest claim that the existence of evil is not logically incompatible with the existence of an all-good, all-powerful God.
Legacy
The word 'theodicy,' which Leibniz coined, has become the standard term for the philosophical problem of evil's relationship to theism. The question Leibniz raised - whether it is possible to justify God in the face of evil - has generated the most sustained literature in the philosophy of religion. His insistence that any answer must be both philosophically rigorous and faithful to the biblical testimony to God's goodness continues to define the terms of the debate.
Key Passages
'It is true that one may imagine possible worlds without sin and without unhappiness, and one could make some like Utopian or Sevarambian romances: but these same worlds again would be very inferior to ours in goodness.' (Theodicy, Part I, sect. 10, trans. Huggard)
Contemporary Relevance
The problem of theodicy has been sharpened in the modern era by the Holocaust and other genocides, which have made Leibnizian optimism seem not merely philosophically naive but morally offensive. Elie Wiesel's Night and the literature of Holocaust testimony constitute a lived refutation of any theology that too quickly resolves the question of evil into a higher harmony. The contemporary philosopher Eleonore Stump's Wandering in Darkness (2010) attempts a new theodicy grounded in the narrative theology of Job, Samson, Mary of Bethany, and Abraham - acknowledging the reality of suffering while arguing for a providential framework. Whether any theodicy can succeed after the twentieth century's catastrophes remains one of philosophy of religion's most urgent and unresolved questions.