Gottfried Wilhelm von Leibniz was born in Leipzig in 1646 and died at the age of 70 in 1716. His philosophy was in part a rejection of the philosophies of Descartes and Spinoza and what he saw as their inadequate explanation of the relationship between "God, man, and nature, each of which Leibniz wanted to keep separate." Leibniz seems to have been determined to create a philosophy which was as positive as possible, rather than to rigorously explore reality scientifically and objectively and declare what he had found whatever it might be. It is no surprise, in that context, to find that Leibniz not only argues for the existence of God, but also goes on to argue that God has essentially created the best of all possible worlds here, despite any evidence to the contrary. Leibniz's optimism seems to fly in the face of all the evidence that this is hardly a perfect world. He means that everything makes sense in the world, whatever happens, if only human beings could have the same perspective which God has.
Leibniz bases his argument for the existence of God on the principle of sufficient reason. He believed that the universe was in a state of harmony, based on the fundamental unit of energy called the monad. The monad is an "unextended" metaphysical entity, with no shape or size, "independent of other monads," with "no causal relation to each other." As odd as this may sound, Stumpf points out that these basic units of energy do call to mind the scientific discoveries of the modern world with respect to the nature of matter. However, Leibniz proposes that these monads are not related causally to one another. Instead, each monad has "its own created purpose."
Clearly, Leibniz had no proof or any evidence for such a claim that the universe was in harmony and that the basis of that universal harmony were invisible entities, each with its own purpose which was not related causally to any other monad. Again, it would seem that this mona...