Leibniz’s effort to solve the “problem of evil,” to provide a rationale for the existence of evil in a world governed by an omnipotent and benevolent God, can seem overly acrobatic to modern audiences. It must be viewed in the context of a time period that not only recognized Christian doctrines as concrete but also afforded value to the human mind as being able to unravel the mysteries of the universe. Leibniz emphasizes the role of reason as a motive in God’s decisions. While earlier Christian thinkers such as Thomas Aquinas had done this to an extent, Leibniz seems to assert that God’s mind might be understood clearly in the terms of human reason and logic, a notion that pre-humanist thinkers were undoubtedly less comfortable with. For early Christian philosophers such as Saint Augustine and Irenaeas, both of whom had produced influential theodicies of their own, the “problem of evil” was about finding a way of reconciling God’s perfect qualities with an imperfect world, while for modern thinkers, especially for atheists, “the problem” is showing that the world’s imperfection in fact proves that there is no God at all. Leibniz’s “theodicy” does not see the “problem of evil” as posing the danger of atheism but rather sees it as challenging the traditional view of God as a being who knew everything, could do everything, and willed good in everything—a notion he wanted to uphold.

Leibniz’s logic relies heavily on the assumptions of a society still overwhelmingly Christian. Some of his arguments, for instance his assertion that God had created the “best possible world,” thus rely on the premises that “God exists” or “God is good,” which modern audiences might view with somewhat greater skepticism than their historical equivalents. Moreover, some of his linguistic choices, such as his insistence that God can create only one “universe,” a word he uses interchangeably with “world,” might seem alien to modern audiences, for whom universe connotes a limited physical and temporal space. For Leibniz, this term simply referred to everything in existence, or more specifically, to everything that God had created.

Leibniz breaks with earlier medieval thinkers, who asserted that while God was complicit with everything in reality, evil was not a reality but rather a lack or “privation” of reality. His argument is that God “permits” evil because evil is a necessary part of larger events that bring about good. For example, the closer cooperation and friendship between nations and the advancement in medical science means that the world wars are justified, with all their horrors. This seems a theological application of the utilitarian principle championed by theorists such as Jeremy Bentham and John Stuart Mill in the nineteenth century (the greatest good for the greatest number).

While for some this permissive conception of God detracts from God’s goodness, it was Leibniz’s only way of addressing the old argument that a metaphysically perfect being like God could not create metaphysically imperfect beings like humans. Leibniz has to subscribe to a certain interpretation of God’s omnipotence, namely that he can only do what is logically possible. To intervene and make humans perfect would, for Leibniz, not be logically possible for God if he wanted to maintain humans as separate beings. If humans were all perfect, we would become one and the same. Understanding omnipotence in this way is sufficient for many philosophers, but for others it does not equate to true omnipotence, since it limits God’s power by the very laws he is said to have put in place.