Best of all possible worlds

The phrase "the best of all possible worlds" (; ) was coined by the German polymath and Enlightenment philosopher Gottfried Leibniz in his 1710 work "Essais de Théodicée sur la bonté de Dieu, la liberté de l'homme et l'origine du mal" ("Essays of Theodicy on the Goodness of God, the Freedom of Man and the Origin of Evil"). The claim that the actual world is the best of all possible worlds is the central argument in Leibniz's theodicy, or his attempt to solve the problem of evil.
Problem of evil.
Among his many philosophical interests and concerns, Leibniz took on this question of theodicy: If God is omnibenevolent, omnipotent and omniscient, how do we account for the suffering and injustice that exists in the world? Historically, attempts to answer the question have been made using various arguments, for example, by explaining away evil or reconciling evil with good.
Leibniz outlined his perfect world theory in his work "The Monadology", stating the argument in five statements: 
To further understand his argument, these five statements can be grouped in three main premises. The first premise (corresponding to the first and second statements) states that God can only choose one universe from the infinite amount of possible universes. (The term "one universe" does not necessarily mean a single three-dimensional physical reality, but refers to the sum total of God's creation, and thus might include multiple worlds.) The second premise (the third and fourth statements) states that God is a perfect existence, and he makes decisions based on reason. The third premise (the fifth statement) concludes that the existing world, chosen by God, is the best.
Leibniz used Christianity to back up the validity of all the premises. For the first premise, God's existence and role as the creator of the world was proven by the Bible. The second premise is proven since "God acts always in the most perfect and most desirable manner possible". Therefore, His choice will always be the best, and only perfect existence can make perfect decision throughout time. Since all the premises are right, then Leibniz concluded, "The universe that God chose to exist is the best of all possible worlds".
To begin his argument, Leibniz conceded that God has created a world with evil in it and could have created a world without it. He argued that this is still the best world God could have made by claiming the existence of evil does not necessarily mean a worse world. In fact, he went as far as to claim that evil's presence creates a better world, as “it may happen that the evil is accompanied by a greater good”. In other words, Leibniz argued that the contrast provided by evil can result in the production of a greater good. Without the existence of evil, everything would be good; goodness would no longer appear good, it would simply be normal and expected, no longer praised. As put by Leibniz: “an imperfection in the part may be required for a perfection in the whole”.<ref name="Thomson/Wadsworth"></ref> The reaction people have from evil can allow them to understand and make decisions that bring about a greater good. God allowed evilness in the world for us to understand goodness which is achieved through contrasting it with evil. Once we understood evil and good, it gives us the ability to produce the "greatest possible good" out of all the goodness. Evil fuels goodness, which leads to a perfect system.
Although this appears like God created evil, which would seem to go against his nature, Leibniz borrowed the same idea Augustine used to fix this issue. “Evil, though real, is not a ‘thing,’ but rather a direction away from the goodness of the One”. Evil is the absence of good and exists in the same way the hole of a donut exists. The donut was created, but one would never say the hole itself was made; it was just never filled in. This also means there cannot be evil without more good, as you can never have the hole in the donut without having donut around it. “God is infinite, and the devil is limited; the good may and does go to infinity, while evil has its bounds”. Using Augustine's model of evil, Leibniz set up the foundation for why a world with evil brings more good, and is therefore better, than a world without evil.
Free will versus determinism.
For Leibniz, an additional central concern is the matter of reconciling human freedom (indeed, God's own freedom) with the determinism inherent in his own theory of the universe. Leibniz' solution casts God as a kind of "optimizer" of the collection of all original possibilities: Since he is good and omnipotent, and since he chose this world out of all possibilities, this world must be good—in fact, this world is the best of "all" possible worlds.
Considering the three factors: good, evil, and free will, God created that best possible world he could with the most good and the least evil, with regards to how free will affects people's choices. This is a short summary of Gottfried Leibniz's Best of All Possible Worlds philosophy regarding the "problem of evil” and how the current world can still be the most viable option. Free will is defined as the “power or capacity to choose among alternatives or to act in certain situations independently of natural, social, or divine restraints”. This basically gives anyone the freedom to do whatever is in their capabilities and inclination—whether it be good or evil. When God breathed the world into existence, He accounted for free will to be a factor of human choice and all the issues it could bring alongside it, as addressed by Leibniz.
“According to Leibniz there are three forms of evil in the world: moral, physical and metaphysical...Since He wills what is best, the world he created has the greatest number of compatible perfections”. These “compatible perfections” are referring to the good and bad effects of choices made through free will. Humans are obviously able to tell the difference from right to wrong, but how they act upon their knowledge is what creates a need for compatibility in the world. God is not the creator of evil, evil is simply the lack of human-induced good. Often, humans make the claim that evil exists because God allowed it into the world, however, “God is not the author of sin”. Sin is necessary in creating the best of all possible worlds and is a result of our free will. There has to be a balance between good and evil in order to maintain the gap between humans and God. If humanity were to be perfect, it would put them on the same level as God, which would destroy the need for grace. Instead, humans are weighed down by their own free will, in perfect contrast to the sovereignty of God. God accommodates for this issue with divine grace and endless mercy to solve the consequences of free will.
In his writing "Discourse on Metaphysics", Leibniz first establishes that God is an absolutely perfect being. He says people can logically conclude this through reason since "the works must bear the imprint of the workman, because we can learn who he was just by inspecting them". He calls this the Principle of Perfection, which says that God's knowledge and power is to the highest degree, more so than any human can comprehend. Due to God's omnipotence, Leibniz makes the premise that God has thought of every single possibility there is to be thought of before creating this world. His perfection gives him the ability to think "beyond the power of a finite mind", so he has sufficient reason to choose one world over the other.
Out of all the possibilities, God chose the very best world because not only is God powerful, but he is also morally good. He writes "the happiness of minds is God's principal aim, which He carries out as far as the general harmony will permit", meaning a benevolent God will only do actions with the intention of good will towards his creation. If one supposed that this world is not the best, then it assumes that the creator of the universe is not knowledgeable enough, powerful enough, or inherently good, for an inherently good God would have created the best world to the best of his ability. It would overall be a contradiction to his good and perfect nature, and so the universe that God has chosen to create can only be the best of all possible worlds.
On the one hand, this view might help us rationalize some of what we experience: Imagine that all the world is made of good and evil. The best possible world would have the most good and the least evil. Courage is better than no courage. It might be observed, then, that without evil to challenge us, there can be no courage. Since evil brings out the best aspects of humanity, evil is regarded as necessary. So in creating this world God made some evil to make the best of all possible worlds. On the other hand, the theory explains evil not by denying it or even rationalizing it—but simply by declaring it to be part of the optimum combination of elements that comprise the best possible godly choice. Leibniz thus does not claim that the world is overall very good, but that because of the necessary interconnections of goods and evils, God, though omnipotent, could not improve it in one way without making it worse in some other way.
Giovanni Gentile, in his work "The General Theory of Mind as Pure Act", claimed that if God had created everything to fall into line with the most favorable possible condition, it would suppose that all of reality is pre-realized and determined in the mind of God. Therefore, the apparent free will displayed by both God, by his necessity of being bound by what is the most good, and humanity in their limitations derived from God to be in line with the most good, are not free wills at all but entirely determinate. Thus ultimately relegated to blind naturalistic processes entrapping both God and humanity to necessity, robbing both of any true freely creative will.
Leibniz, unlike Giovanni, does believe humans have free will despite the predetermined nature of the world. His argument revolves around the idea that “if it is certain that we shall perform them, it is not less certain that we shall choose to perform them.” He maintains that God has chosen this universe and that all things will fall in line with the best world, but we still have choice. For example: if you were to either between vanilla or chocolate ice-cream. You choose chocolate, the choice god knew you would. However, there is a separate, non-perfect, universe in which you chose vanilla. This gives you similar results to Multiverse theory.
Leibniz's multiverse acts differently than ones we are accustomed to. Unlike modern multiverse or even unlike the ancient ideas posed by the atomists in ancient Greek times, Leibniz does not believe all the possible universes exist. Decisions do not create branching universes depending on your decision and there is no other, less perfect universe, existing alongside our own. It is only the perfect universe we live in. This is due to the nature of God choosing the universe. It is as if God sees all the possible universes and chooses the one he wants, the perfect one, and creates only that one.
Criticism.
Following the devastating Lisbon Earthquake (1 November 1755), which occurred decades after the publication of the "Essais de Théodicée sur la bonté de Dieu, la liberté de l'homme et l'origine du mal" (1710), Leibniz's philosophical optimism and theodicy incurred considerable criticism both from his fellow Enlightenment philosophers and Christian theologians as well. Critics of Leibniz, such as Voltaire, argue that the world contains an amount of suffering too great to justify optimism. While Leibniz argued that suffering is good because it incites human will, critics argue that the degree of suffering is too severe to justify belief that God has created the "best of all possible worlds". Leibniz also addresses this concern by considering what God desires to occur (his antecedent will) and what God allows to occur (his consequent will). Others, such as the Christian philosopher Alvin Plantinga, criticized Leibniz's theodicy by arguing that there probably is not such a thing as "the best" of all possible worlds, since one can always conceive a better world, such as a world with one more morally righteous person.
The "Theodicy" was deemed illogical by the philosopher Bertrand Russell. Russell argues that moral and physical evil must result from metaphysical evil (imperfection). But imperfection is merely limitation; if existence is good, as Leibniz maintains, then the mere existence of evil requires that evil also be good. In addition, libertarian Christian theology (not related to political libertarianism) defines sin as not necessary but contingent, the result of free will. Russell maintains that Leibniz failed to logically show that metaphysical necessity (divine will) and human free will are not incompatible or contradictory. He also claims that when Leibniz analyzes the propositions, he is “ambiguous or doubtful...” (O’Briant). Leibniz does not sound sure and is unsure of himself when he writes his premises. He says they do not work together without making Leibniz sound unsure of himself.
Another philosopher who weighs into Leibniz's philosophy is Kant. Although Leibniz influenced Kant a great deal, Kant found that Leibnizian philosophy “misleading.” (Kant and Early Moderns). He says that the misleading nature of Leibniz's works is due to the one-sidedness of the theory.
The physiologist Emil du Bois-Reymond, in his "Leibnizian Thoughts in Modern Science" (1870), wrote that Leibniz thought of God as a mathematician:
Du Bois-Reymond went on to argue that even Charles Darwin supported a version of Leibniz's perfect world, since every organism can be understood as relatively adapted to its environment at any point in its evolution.
Nonetheless, the statement that "we live in the best of all possible worlds" drew scorn, most notably from Voltaire, who lampooned it in his comic novella "Candide" by having the character Dr. Pangloss (a parody of Leibniz and Maupertuis) repeat it like a mantra when great catastrophes keep happening to him and Candide. From this, the adjective "Panglossian" describes a person who believes that the world about us is the best possible one.
While Leibniz does state this universe is the best possible version of itself, the standard for goodness does not seem clear to many of his critics. To Leibniz, the best universe means a world that is “the simplest in hypotheses and the richest in phenomena”, in addition to the “happiness of minds” being God's main goal. Voltaire, Bertrand Russell, and other critics seem to equate goodness of the universe to no evil or evil acts whatsoever, presuming that a universe that did not contain evil would be "better" and that God could have created such a universe, but chose not to. According to Leibniz, that is not the case. He believes that if a better alternative existed “God would have brought it into actuality”. Essentially, Leibniz affirms that no human can truly think of a better universe because they lack a holistic understanding of the universe, and God, who has that holistic understanding, has already chosen the best option. All of this shifts the meaning of goodness from morality and actions to the quality and phenomena of this universe's existence. Despite that, the concept of the goodness of the universe is still a point of major contention in Leibniz's argument, as someone could always argue about the lack of goodness in the universe based on those parameters.
While not directly criticizing Leibniz, Spinoza holds a drastically different view on creation and the universe. Spinoza believes “that everything that God thinks or conceives must also exist”, and he combines God's will and God's understanding where Leibniz separates them. In other words, God cannot imagine an infinite number of worlds and “as a separate act of will” choose one of those to create. How does Spinoza explain creation then? To put it simply, everything in the universe “is a direct result of God's nature”. The moment God thinks of something, it exists. As there are not an infinite amount of universes (according to Spinoza and Leibniz) God must have only conceived of one universe. This, however, still runs into the problem of the existence of evil. How can God, in His perfection, create a world capable of evil if the world is an extension of his mind? In any case, Spinoza still tries to justify a non-infinite basis for the universe, where reality is everything God has ever thought of.
Other philosophers.
Stoicism's theory of determinism is also provedentialism. Consequently, this world is not only the only possible world, it is the best of all possible worlds. 
Aquinas, using Scholasticism, treats the "Best of all possible worlds" problem in the "Summa Theologica" (1273):
He counters this in general by the "quinque viae", and in particular with this refutation:
More recently, the theological theory of pandeism has been classed as a logical derivation of this proposition with the contention that: