Leibniz was a German mathematician, inventor, and philosopher born in Leipzig in 1646. He is best known for his work the Monadology, where he puts forth the idea that the world is fundamentally composed of entities he calls monads. As these monads are immaterial entities, each with it’s own particular consciousness, Leibniz is considered an Idealist. Leibniz is also known for his work Theodicy, where he explains how it is possible for there to be evil in the world if God is all-knowing and good. Leibniz believed that we live in the best possible world, where everything has been arranged by God by the principle of “pre-established harmony.” Along with Descartes and Spinoza, Leibniz is one of the most famous rationalist philosophers in the 17th century.
Living in the 17th century, Leibniz did practically everything. He was a mathematician, invented calculus at the same time that Newton, although this was famously disputed in his day). He was an inventor, having invented a calculating machine which led him to become an honorary member of the Royal Society of London. He was a statesman, who crafted a plan for France to attack Egypt instead of Germany at a time when France under Louis XIV was strong and Germany was weak (originally considered, the plan was ultimately passed up, although used over a century later by Napoleon).
Descartes’ philosophy had made a large impact on Europe in the 17th century. Descartes put forth a view of the world in which there were thinking substances (mind) and extended substances (matter), known as mind-body dualism. This view of the world brought up the tricky question of how the mind and body relate to each other. In response, some materialist philosophers suggested that there is only matter, and that consciousness can be explained as being a physical process. Leibniz did not think this was true. He was himself an inventor and mechanical engineer, and didn’t believe it was possible for the human mind to be a machine, even a highly complex machine. Instead, he would offer his own alternative, whereby he explains that the world is made of only one type of substance, which is immaterial.
In his Monadology, Leibniz explains that the world is made up of indivisible units known as “monads.” Rather than being material entities, such as atoms, Leibniz’ monads are immaterial. Their defining characteristic is that they are forces. Each monad has its own consciousness, which reflects or “mirrors” the rest of the universe. These monads are arranged in a way such that they don’t interact with each other, but exist in perfect harmony. Leibniz explains that God, who is also a monad, in his infinite wisdom arranged all monads to create what is the best of all possible worlds according to the principle of “pre-established harmony.”
Leibniz explains that the natural world appears to us to consist of material objects, but in reality these are merely combinations of monads. While all monads have consciousness, certain monads such as the human spirit have a “higher” form of consciousness, while other monads such as rocks have a “lower” form of consciousness. The human body is therefore not the combination of mind and spirit, as Descartes believed, but the combination of monads of higher and lower forms of consciousness. In this way, Leibniz was able to show that in reality (i.e. metaphysically), everything in the universe was immaterial (this form of idealism, based on their being one substance, is known as monism).
The philosophy of the Monadology is optimistic. God, who is perfect, naturally created what Leibniz believes is the best possible world. Leibniz will go on to explain in his work Theodicy how, therefore, evil can exist in the universe. Leibniz explains that as human beings, we are limited. In his language, as monads we can only reflect the nature of the universe from our particular point of view. God, as the greatest Monad with the greatest degree of consciousness, of course is able to reflect on the entirety of the universe, which he arranged according to the principle of “pre-established harmony.” Therefore, God created the best possible world, we just aren’t able to recognize that from our limited vantage point.
Leibniz believed philosophies such as his own could be employed to support Christian theology. Influenced by medieval scholastic thinking, he saw faith and reason as compatible, as both are “gifts from God.” In addition to giving a rational account for God existence, creating a system which shows his relationship to the rest of the world, and demonstrating how God can be perfect and yet evil exists in the world, Leibniz also sought to reconcile the schism that had formed between Catholics and Protestants. He believed his philosophy could serve as a common ground for all Christians.
In the 18th century, the French writer and philosopher Voltaire would ridicule Leibniz and his philosophy, in particular his belief that we are living in the “best of all possible worlds.” In his famous work Candide, the character Pangloss, a professor of “metaphysico-theologo-comonigology,” explains that no matter what happens, everything is for the best. When his friend Candide asks him “When you were hanged, dissected, thrashed on the wheel, cruelly beaten, and forced to row in the galleys, did you still think that everything in this world is for the best?” Voltaire has Pangloss reply, “I always hold to my original opinion, because after all, I’m a philosopher.” Likewise, since “everything was made for a purpose,” Pangloss will explain how “noses were made for spectacles, legs were made to wear pants,” and when Jacques the Anabaptist drowned in Lisbon harbor, “the harbor was formed expressly for the Anabaptist to drown in.”
Leibniz was constantly active in thinking and working on projects. As an engineer, he worked on hydraulic presses, submarines, clocks, and even invented a steam engine. He came up with an idea for a computer based on a system of marbles, as well as created the binary number system which is used in most computers today. He was also the first major European philosopher to show an interest in Chinese philosophy, noticing the similarities between his binary system and the I Ching (“Book of Changes”). In politics, he called for the creation of a European Federation, while as a scientist he called for the creation of a “community of minds” which is seen as having been realized in our time with the invention of the internet.
Leibniz was also before his time in his understanding of physics and logic. Unlike Newton, who saw space and time in absolute terms, Leibniz viewed them as simply pragmatic concepts which help us to understand the world as it appears to us (i.e. science). Leibniz’ relative understanding of time and space would be demonstrated by Einstein in the 20th century. In logic, he put forth several principles, including the principle of contradiction which states that if a proposition is true, it’s opposite must be false, which would also be picked up and built upon in the 20th century. More immediately, Leibniz’ ideas would influence Hume, who opposed rationalism with his own understanding of the world based on sensory experience (known as empiricism), as well as Kant, who at the end of the next century would transcend this debate in modern philosophy.