One of the most well-known doctrines of Leibniz is the doctrine of possible worlds. It is essential to understanding Leibniz’s system. Furthermore, everyone is familiar with his book Theodicy in which he attempts to demonstrate that this world in which we live is the best of all possible worlds, in spite of the evil that we cannot escape. He attempts to solve, in this book, the problem of evil. The problem of evil is, essentially, how could an all-knowing, omnibenevolent, all-powerful God create a world in which there is evil of all kinds. Eleonore Stump, who recently published what is probably the most important modern work on the problem of evil, explains that “It has become customary to divide evil into natural evil and moral evil...But so-called natural evil would not raise the problem of evil if there were no sentient creatures who suffered from hurricanes, viruses, and the rest. It is the fact of suffering, not its origin, that raises the problem of evil in connection with so-called natural evil.” She goes on to show that the same fact is also true of moral evil. That is, in the cases of both natural evil and moral evil, “what is in need of justification is God’s allowing suffering.” So, the problem of evil primarily concerns the suffering of sentient beings. I raise the problem of evil, in this paper, because it is the question that comes immediately to mind once we have understood Leibniz’s claim that this world in which we live is the best of all possible worlds.
The primary purpose of this paper is to explain Leibniz’s doctrine of possible worlds, and as a corollary to explain, according to Leibniz, the presence of evil, or rather, suffering. In order to do this, I will begin by explaining some definitions and important concepts that Leibniz relies on for his doctrine of possible worlds. Then, I will explain why this world in which we live is, according to Leibniz, the best of all possible worlds. Finally, I will turn to the problem of evil, exposing Leibniz’s solution to this problem, which is, I propose, ultimately, only a problem in Leibniz’s system, and based upon his doctrine of possible worlds.
Definitions and Important Concepts
First of all, according to Leibniz, an Essence, which he frequently equates with the term perfection, or natures, is primarily, “that which includes everything we express...it has no limits and nothing surpasses it.” It is the complete idea of the thing in question. Furthermore, Leibniz describes an essence or perfection as “an urge for existence from which existence indeed follows per se, not necessarily, but from the denial that another thing more perfect prevents it from existing.” This definition coincides with what he says elsewhere, “essence in and of itself strives for existence.” It is important to keep in mind that, for Leibniz, “possibility is the foundation [source, or principle] of essence.” Therefore, an essence, for Leibniz, is a possible thing, including its complete idea or notion, which strives for existence.
We must consider, in relation to the term essence, the terms perfection, possible thing, world, and existence. Perfection, according to Leibniz, can be defined as “the amount of essence”, or, the “degree of essence”. In the Monadology he defines perfection as “being nothing but the magnitude of positive reality considered as such, setting aside the limits or bounds in the things which have it.” In a letter to Wolff he defined perfection in a slightly deeper manner, “Perfection is the harmony of things, or the state where everything is worthy of being observed, that is, the state of agreement or identity in variety; you can even say that it is the degree of contemplatibility.” This is not a contradiction, the application of the preceding definition to the entire universe. For, a perfect state, according to Leibniz, is that in which the greatest amount, or the greatest degree, of essences are brought into existence. It is important to note that, for Leibniz, “the perfection a thing has is greater to the extent that there is more agreement in greater variety.”
Existence, in Leibniz, is equated with actuality, or being actual. He also agrees with Descartes that existence is a perfection. Furthermore, existence is not only a perfection, but it depends upon perfection as a principle or cause. “perfection or degree of essence (through which the greatest number of things are compossible) is the foundation of existence.”
A possible thing is that which expresses essence or possible reality, it is a thing that strives for existence. A thing is possible by (or in) its nature, when, in itself, it “implies no contradiction.” The striving of a possible thing for existence is in proportion to the degree (amount or quantity) of essence (perfection or reality) that it contains in its complete idea. The World is the complete collection of actually existing finite things.
Before we can finish this section we must consider four other concepts that are essential to any explanation of Leibniz’s possible worlds. First of all, metaphysical necessity, or absolute necessity, can be affirmed of a thing, when the contrary of the thing in question implies a contradiction. Physical or hypothetical necessity is affirmed of a thing when the contrary of that thing implies either imperfection or moral absurdity. Decision rule is the choice of “maximum effect at the minimum cost.”
Finally, the Principle of Sufficient reason claims that “nothing takes place without a sufficient reason.” In other words, “that nothing happens without it being possible for someone who knows enough things to give a reason sufficient to determine why it is so and not otherwise.” The principle of sufficient reason is the claim that for anything that exists, or that happens, there is a sufficient answer to the questions “why does this exist? (why did this happen?)” and “why does it exist in this way and not in another way? (why did it happen this way and not another way?)” With these principles in hand we will now expose Leibniz’s theory of possible worlds.
Leibniz’s Theory of Possible Worlds
According to Leibniz there is an infinity of possible worlds. These possible worlds are all found in Gods ideas – the realm of the possible. These possible worlds are, in themselves, complete and coherent, yet, quite obviously, they cannot coexist, as the existence of one possible world implies the non-existence of every other possible world. Therefore, only one possible world could be made actual. There are two questions that we must ask of Leibniz; questions which he actually asks himself. Why does this particular possible world exist? Why are there certain possible things that don’t exist?
Why is this Particular World Actual?
The question has two aspects, we are asking, essentially, what is the sufficient reason for the existence of this particular world (Why does this world exist?)? However, we are also asking Why does this world exist in the way that it does? We will treat these two questions together. Leibniz gives two answers to this question, one is based upon the world itself, and the other on God. First of all, this world is actual based upon the definitions of possibility, perfection and existence. Possibility, as we said above, is the principle of essence, and perfection (which is the degree of essence) is the principle of existence. Now, “all possible, that is, everything that expresses essence or possible reality, strive with equal right for existence in proportion to the amount of essence or reality or the degree of perfection they contain.” Therefore, that possible world that is made actual is the world that contains the greatest amount of perfection or degree of essence. In other words, out of all of the possible worlds realizable this world is the best possible world. We might attempt to imagine a world that is more perfect, but, according to Leibniz’s definitions, if such a world was possible this would be it.
This first answer, by itself, would leave us unsatisfied, but, the second answer guarantees that this is indeed the best of all possible worlds. The second reason, the ultimate sufficient reason, why this world is the best of all possible worlds is that God chose this world out of all the possible worlds. God’s choice, flowing from his infinite wisdom, was made by decision rule and based upon the principle of fitness. The principle of fitness concerns “the degree of perfection that these [any and all possible worlds] worlds contain.” That world is fit for existence, as we noted above, which contains within itself, and the composition of all of its parts, the greatest degree of perfection. Now, decision rule demands that God create that world with the greatest degree of perfection, or, as Leibniz says elsewhere, that world that is “at the same time the simplest in hypotheses and the richest in phenomena.” In other words God creates that world that has the greatest amount of “agreement or identity in variety,” which contains the “greatest variety together with the greatest order,” or “which is the most appropriate,” and “best”. God, in fact, chooses to bring into existence that possible world which contains, “the most power, knowledge, happiness and goodness.” Leibniz explains, in the Monadology, that, through God’s wisdom He knows which possible world has the greatest degree of perfection, through His goodness He chooses to create it, and by His power He produces it. God, then, for Leibniz, is the ultimate sufficient reason for the existence of things.
Yet, is not the introduction of God, as the ultimate source of all existing things, a little gratuitous? Is there not something else that could be the ultimate sufficient reason for the existence of this universe? Something else that answers the question why the world exists and why it exists the way that it does?
Leibniz has an answer to this question as well. If God, a being that is not a part of the universe, is not the sufficient reason for the existence of this world, then what could take His place? One answer that has been given throughout the history of philosophy is: Matter. Leibniz, in the Principles of Nature and Grace, Based on Reason, takes this answer head on. He claims that matter (or energy, protons, neutrons or electrons), could not possibly be the ultimate cause (reason) of the existence of all things, because it is absolutely indifferent to motion or to rest. Pure matter is unable to be the ultimate sufficient reason as it itself is in need of a sufficient reason to be either in motion or at rest. Regardless of how far back we go in the spatio-temporal states of the universe, we will never find a reason, coming from matter, why things are the way they are and not otherwise. Therefore, the ultimate sufficient reason for the why there is something rather than nothing cannot possibly be matter.
We could always just avoid the problem by saying that the universe is eternal. That is, regardless of how far back you go, you will never actually reach a beginning of the universe. There is a constant flow of spatio-temporal, contingent, states of the universe. Leibniz addresses this issue in much the same way that he addresses the question of matter. He says that this answer, positing an infinite regress of finite, or contingent, beings, or spatio-temporal states, still does not give us an ultimate sufficient reason for the existence of this world. Why is this? First of all, the reason for an unchanging thing (a persisting thing) is its own nature or essence. However, the reason for a contingent thing (or even an infinite series of contingent things) is “the superior strength of certain inclinations”, that is, the strength of its striving for existence. But its striving for existence does not give it existence as it is still only possible until it receives existence. Therefore, the ultimate sufficient reason for the existence of the universe, the compilation of contingent essences, cannot be found in any one contingent essence, nor in the total compilation of contingent essences. Therefore, concludes Leibniz, the ultimate sufficient reason for the existence of the universe must depend upon something which is: not contingent, nor part of the continent universe. Such a being, would, according to Leibniz, would exist by its very essence, that is to say, it would be “an entity whose essence is existence.”
These two arguments, which sound very much like the cosmological argument for the existence of God, are used in Leibniz to provide us with that necessary being that is capable of choosing, and producing, the most perfect world. If these arguments are sound and valid, then Leibniz has proved that this is the best possible world that could be created. The questions remains, why are there possible things that don’t exist?
Why are there Possible Things that don’t Exist?
In his letters to Des Bosses, Leibniz can be quoted as saying that “there is a reason why not every possible thing exists.” Furthermore, we know, based upon the principle of sufficient reason, that there must be a sufficient reason for every state of affairs. Leibniz might have attempted to argue to that seeing as possible things that will never be created are not actual, they, are, therefore, not a state of affairs. However, due to the fact that he puts all possibilities, all possible worlds in the ideas of God, he tends to say that they exist, as ideas or notions, in God’s mind. Therefore, he needs to explain how it is possible for there to be possible things in God’s mind which are not made actual. To some, such a question might not seem important, for example, does it really matter that the possibility that I drink two cups of coffee this morning did not come to be? Do I really care why that possible state of affairs does not exist? Put that way, it does sound like a trivial question. However, this question, which will lead us into the problem of suffering, could be worded differently. Why did that state of affairs in which the twin towers were not destroyed, which was certainly possible, not come to pass? They were destroyed, but, it was possible that the terrorists never exist, or that they get caught. Why did the state of affairs, in which a woman is not raped, not exist? Why did the state of affairs in which my grandfather did not get brain cancer, which was entirely possible, not exist? Put this way, this question takes on a whole new meaning.
He answers question in the short article On Freedom and Possibility. Leibniz’s answer is based upon all of the principles that we have already seen. He claims that if X is possible in its nature, but does not exist, or come to pass, it is because it is, or was, “incompatible with other things that include more perfection, that is, with other things that include more reality,” which exist already, have existed, or will exist. Though it was, or is, physically (or hypothetically) possible that X happen, or receive existence, due to the other parts of this actual world, its non-existence is physically, though not metaphysically, necessary. This answer does not seem satisfying to those who have experienced great suffering. This leads us on to our final section in which we will look at how Leibniz answers the problem of evil, based upon the principles of possible worlds.
Possible Worlds and The Problem of Evil
The question that we just finished answering, in Leibniz’s terms, brings us to the problem of evil, or, as mentioned in the introduction, the problem of suffering. The problem, as Franklin Perkins notes, “is not just that we suffer more than necessary but also that the suffering is not fairly distributed.” As I said above, the problem of suffering is that it seems that if there is a God that is all-knowing, omnibenevolent, and all-powerful (at least these three attributes together), then it seems that God should actualize that world in which there is the least amount of suffering. However there is all too much suffering in this world, in fact, we can all imagine a world in which there is at least one less murder or rape victim. If God was such as described above, then He would have created that world, instead. Therefore there cannot possibly be a God, at least as described above. At best, if there is a God, in order to create such a world as this, He couldn’t possibly be either all-knowing or omnibenevolent or all-powerful, or all three. This is the problem of evil.
There are many different philosophers who have attempted to answer this problem, but in this section we will look at Leibniz’s answer to the problem of evil, based upon the principles that we saw above. According to Leibniz, as we saw above, God, through his omniscience and divine wisdom knew which, of the infinity of possible worlds, was the best. Through his goodness God willed to create the best possible world, and through His supreme power He produced the best possible world. This possible world includes all the finite creatures that are found in its idea. Each of these creatures, in each possible world, has a complete idea in the mind of God which includes its entire spatio-temporal possible existence, including, for rational creatures their thoughts and actions. God, knowing all possible worlds, with all possible creatures and all their possible actions, knows which of those possible worlds is the best, and declares that this world exist. From that point on, he simply keeps it in existence – preserving the being of each thing in it. For God to interfere significantly (unless His divine action in contingent affairs is a part of the best possible world) with the being of any one contingent thing would, essentially, be to choose an entirely different world (which would contain less perfection then the best possible world). Therefore, God preserves each being (animate or inanimate), each action or event, guaranteeing that they each accomplish or live out their complete idea. This means that, according to Leibniz, and based upon his principles and definitions, and especially based upon his theory of possible worlds, we are living in the best possible world. Not one evil event or act could be removed without making the world less perfect, because that which exists is based upon the total perfection of the world in question.
Though this answers the problem of evil, on a large scale, it doesn’t answer the problem of evil on a small scale. In other words, it begs the question, which Leibniz asks and immediately answers, “Why is it that this man will assuredly commit this sin? The reply is easy: otherwise he would not be this man.” We might add to his answer, based on the above principles, that, otherwise this would not be the greatest, best, most perfect, possible world, because, each individual part of this world includes within its complete idea the entire possible world.
We could be even more specific, as Leibniz was, “Why does such a Judas, the traitor, [insert anybody here, Hitler, Statesman Mao, the man who raped that girl, Bundy] who is merely possible in God’s idea, actually exist?” He had to exist because he was part of the most perfect, best, possible world realizable. Leibniz says, “Since God found it good that he should exist, despite the sin that God foresaw, it must be that this sin is paid back with interest in the universe, that God will derive a greater good from it, and that it will be found that, in sum, the sequence of things in which the existence of the sinner is included is the most perfect among all the possible sequences. But we cannot always explain the admirable economy of this choice while we are travellers in this world; it is enough to know it without understanding it.” Leibniz’s response is that, though we only consider the contingent act of that person, or this contingent evil, God considers the entire series of contingent things, persons, and acts, in the spatio-temporal universe and this particular moment, that we have in mind (evil as it is), is physically necessary.
One final question, Why must evil, or suffering exist at all? First of all, Leibniz notes that, technically, evil is a necessary fact for created being. He gives many examples of what he means,
Indeed, the most distinguished masters of composition quite often mix dissonances with consonances in order to arouse the listener, and pierce him, as it were, so that, anxious about what is to happen, the listener might feel all the more pleasure when order is soon restored, just as we delight in small dangers or in the experience of misfortune for the very feeling or manifestation they provide of our power or happiness, or just as we delight in the spectacle of ropewalkers or sword dancing for their very ability to incite fear, or just as we ourselves laughingly half toss children, as if we are about to throw them off...On that same principle it is insipid to always eat sweet things; sharp, acidic, and even bitter tastes should be mixed in to stimulate the palate. He who hasn’t tasted bitter things hasn’t earned sweet things, nor, indeed, will he appreciate them. Pleasure does not derive from uniformity, for uniformity brings forth disgust and makes us dull, not happy: this very principle is a law of delight.
We might add that pain is often necessary for good things, for example, a tooth ache alerts us to a cavity, and repairing the cavity, a good, can be painful. Getting in good shape, physically, is painful. Most of the good things of life cannot be appreciated properly without a prior pain or suffering.
This, of course does not answer the question we asked, but it is part of the answer. The reason why evil and suffering exists has to do with the fact that we are limited creatures. “The cause of evil derives from the original limitation of creatures, before all sin.” In the Dialogue on Human Freedom Leibniz takes this question head on. He says that the cause of evil is, in a sense, nothingness. This is so because, “evil is a defect, that is a privation or negation, and consequently, it arises from nothingness or nonbeing.” This limitation, which is part of our nature, is inevitable. It is part of the definition of a created, contingent, being. To be created is to be limited. This limitation is the ultimate source of evil in the universe: limitations in inanimate things, limitations in animals, and limitations in human beings. Due to our limited knowledge, power, wisdom and goodness, human beings can cause evil, hurting and killing others. God could not have created any possible world in which there was no evil, because evil is by definition a negation of being, and all created things are imperfect. Therefore, for contingent, created, beings, evil is a necessity. Without evil there would be no creation.
Leibniz’s answer to the problem of evil, though it may not satisfy that person who is suffering at this moment, does seem, if we accept his principles and definitions, to be true. This personal problem of evil (why did this happen to me?) is not a problem that a philosopher should address, even if, philosophically speaking his answer is true. The personal problem of evil needs a comforting friend, counselor, psychologist or pastor.
The primary purpose of this paper was to expose Leibniz’s doctrine of possible worlds, and to show the coherence of his claim that this is the best possible world. In the process we showed how Leibniz answered, with the theory of possible worlds, the problem of evil. Possibility, as the principle of essence, is found in the mind of God, and God knows all possible worlds and all the parts of all possible worlds. We, however, only know what might be possible based upon what is actual. We only have a posteriori knowledge of possibilities. As such it is difficult for us to accept Leibniz’s claim that this is the best of all possible worlds. However, as, I hope, I have made clear, Leibniz’s system is, if we accept his definitions and the principle of sufficient reason, eminently coherent. I would argue, in fact, that the entire problem of evil, hinges, not on the claim that God, as an all-knowing, omnibenevolent, all-powerful being, could not have made a world with evil, but rather, on the principle of sufficient reason, and the definitions that Leibniz gives to the terms perfection, existence and essence. Without these definitions, and the principle of sufficient reason there is absolutely no reason to think that God could not create a world in which there is evil. The notion of such a God and the notion of evil are not contradictory terms. However, though Leibniz’s problem of evil was caused by his own terms and principles, he dealt with the problem in a coherent and rational way. Though we may not like his answer, unless we take exception to his definitions or principles we cannot reject it.
We began by explaining the terms, and principles, that Leibniz uses in the doctrine of possible worlds. We then used these terms to explain the doctrine of possible worlds and why Leibniz claims that this is the best of all possible worlds. This is, according to Leibniz, the best of all possible worlds because only perfection is the foundation of existence, and because God, who is all knowing chose that possible world that would exhibit the most perfection. We finished by exposing Leibniz’s solution to the problem of evil. Evil is a necessary fact of life that, rather than demonstrate that God (as normally described in Christian literature) could not possibly exist, is a result of creation. God didn’t have to create anything, but, by the fact that He did, he allowed for the existence of suffering.
Eleonore Stump, Wandering in Darkness : Narrative and the Problem of Suffering (Oxford: Oxford University Press, 2010), 4.
Cf. G. W. Leibniz, “On Freedom and Possibility,” in Philosophical Essays, trans. Roger Ariew and Daniel Garber (Indianapolis, IN: Hackett Publishing, 1989), 20. G. W. Leibniz, “On the Ultimate Origination of Things,” in Philosophical Essays, trans. Roger Ariew and Daniel Garber (Indianapolis, IN: Hackett Publishing, 1989),150, 151.
Cf. G. W. Leibniz, “Dialogue on Human Freedom and the Origin of Evil,” in Philosophical Essays, trans. Roger Ariew and Daniel Garber (Indianapolis, IN: Hackett Publishing, 1989), 114.
Cf. G. W. Leibniz, “Discourse on Metaphysics,” in Philosophical Essays, trans. Roger Ariew and Daniel Garber (Indianapolis, IN: Hackett Publishing, 1989), 47.
Leibniz, On Freedom and Possibility, 20.
Leibniz, On the Ultimate Origination of Things, 150.
G. W. Leibniz, “The Monadology,” in Philosophical Essays, trans. Roger Ariew and Daniel Garber (Indianapolis, IN: Hackett Publishing, 1989), 218.
G. W. Leibniz, “From the Letters to Wolff,” in Philosophical Essays, trans. Roger Ariew and Daniel Garber (Indianapolis, IN: Hackett Publishing, 1989), 233-4.
Leibniz, On the Ultimate Origination of Things, 151. Cf. Leibniz, The Monadology, 218.
G. W. Leibniz, “Letter to Countess Elizabeth, On God and Formal Logic,” in Philosophical Essays, trans. Roger Ariew and Daniel Garber (Indianapolis, IN: Hackett Publishing, 1989), 237.
Leibniz, On the Ultimate Origination of Things, 151.
Ibid., 150. Cf. G. W. Leibniz, “On Freedom and Possibility,” in Philosophical Essays, trans. Roger Ariew and Daniel Garber (Indianapolis, IN: Hackett Publishing, 1989), 21..
Leibniz, On Freedom and Possibility, 21.
Ibid., 150, 151.
G. W. Leibniz, “Principles of Nature and Grace, Based on Reason,” in Philosophical Essays, trans. Roger Ariew and Daniel Garber (Indianapolis, IN: Hackett Publishing, 1989), 210.
Leibniz, The Monadology, 220. G. W. Leibniz, “From the Letters to Arnauld,” in Philosophical Essays, trans. Roger Ariew and Daniel Garber (Indianapolis, IN: Hackett Publishing, 1989), 71, 72. G. W. Leibniz, “From the Letters to Johann Bernoulli,” in Philosophical Essays, trans. Roger Ariew and Daniel Garber (Indianapolis, IN: Hackett Publishing, 1989), 170-1.
Leibniz, On the Ultimate Origination of Things, 151. Leibniz, The Monadology, 220. Leibniz, The Letters to Arnauld, 73, 75. I will address a little further on, why God is necessary, not only for the existence of this actual world, but for the possibility of possible worlds.
Two possible worlds may be very similar but between any two possible worlds there is at least one difference, otherwise they would be numerically the same. That difference means that they both cannot be actual. For example: In possible world 1 I was born in Brantford, Ontario, but, in possible world 2 I was born in Hamilton Ontario. Now, these two towns are very to each other, it takes about a half hour to drive between the two towns. The interesting fact about possible worlds is that, if in possible world 1 I have a different birth place than I do in possible world 2, then there are a lot of other things that are going to be different between possible world 1 and 2. Yet, we have only changed one fact, supposedly. Some of the consequences of a difference of birth place are that my parents would have had to either live in a different town, or drive further to get to the hospital in the neighboring town when I was born, etc.
Leibniz, The Monadology, 220.
Leibniz, On Freedom & Possibility, 21.
Leibniz, On the Ultimate Origination of Things, 150.
Ibid., 150-1. Cf. Leibniz, The Monadology, 220. Leibniz, Principles of Nature and Grace, Based on Reason, 210. Leibniz, Letters to Johann Bernoulli, 170-1.
Leibniz, The Monadology, 220.
Leibniz, Discourse on Metaphysics, 39.
Leibniz, Letters to Wolff, 234.
Leibniz, Principles of Nature and Grace, Based on Reason, 210.
Leibniz, Letters to Johann Bernoulli, 170-1.
G. W. Leibniz, “Letter to Coste, On Human Freedom,” in Philosophical Essays, trans. Roger Ariew and Daniel Garber (Indianapolis, IN: Hackett Publishing, 1989), 194.
Leibniz, Principles of Nature and Grace, Based on Reason, 210.
Leibniz, The Monadology, 220.
 Leibniz, Principles of Nature and Grace, Based on Reason, 210.
Leibniz, On the Ultimate Origination of Things, 149.
G. W. Leibniz, “From the Letters to Des Bosses,” in Philosophical Essays, trans. Roger Ariew and Daniel Garber (Indianapolis, IN: Hackett Publishing, 1989), 202.
Leibniz, On Freedom and Possibility, 21.
Franklin Perkins, Leibniz: A Guide for the Perplexed (New York, NY: Continuum, 2007), 41.
All the actions of rational creatures are freely committed, because God is not forcing them to act, rather, in a theory that is very molinistic, God, simply declares that the best possible world exist, along with all the free, contingent, actions of its creatures. This of course is bordering on another subject, the sovereignty of God and human free-will, which is much too involved for us to be able to treat it in this short paper.
Leibniz, Discourse on Metaphysics, 61.
For an explanation of how the changing of even one event, such as, for example, that Hitler die in his childhood, changes the entire possible world in numerous important aspects, see footnote 29.
Leibniz, Discourse on Metaphysics, 61.
Leibniz, On the Ultimate Origination of Things, 153.
G. W. Leibniz, “The Source of Contingent Truths,” in Philosophical Essays, trans. Roger Ariew and Daniel Garber (Indianapolis, IN: Hackett Publishing, 1989), 100.
G. W. Leibniz, “Dialogue on Human Freedom,” in Philosophical Essays, trans. Roger Ariew and Daniel Garber (Indianapolis, IN: Hackett Publishing, 1989), 113.
Leibniz, Letters to Arnauld, 75.