Gottfried Wilhelm Leibniz (1646 - 1716) is currently being recognized for his contribution to the development of the computer. He produced the first binary logical number system, invented calculating machines, stated the physical law of conservation, among other achievements [as if that weren't enough!]. He and Isaac Newton independently discovered calculus, which is a mathematical foundation of modern science and engineering.
Leibniz pictured the creation of an artificial language - such as symbolic logic - that could be translated to and from our natural everyday languages. Such an artificial, or "universal," language would have the advantage of being precisely calculated and corrected.
Leibniz was serious about the prospect of encoding human thought into an abstract form. As such a feat would require a rigorous system of organization, he dedicated much of his effort the systematic organization of existing knowledge across the disciplines. He worked to establish major libraries and organize scientific societies.
Throughout history Leibniz has often been identified with his work on the problem of evil in his book Theodicy. The problem of evil is an ancient issue that continues to create controversy today. In it's theological version, the problem has to do with whether the idea of an omnipotent (all powerful) and perfectly benevolent (all-good) God is consistent with the existence of evil in the world.
Some people respond to this argument rather immediately with a response such as "Don't blame God! Humans cause evil, not God." That is a fair point, but it is not germane to the argument. The argument says nothing about blame or causes, only capacities. If God has the capacity to prevent evil and does not do so, then God does in fact allow evil to happen. One can go further to explain why this is so, but the fact that it is so conflicts with the idea of God as perfectly good (i.e. with no evil at all). Which such an account, we may be pressed to formulate a dualistic concept of God that is both good and evil (rather than perfectly and only good).
Leibniz sought to solve the problem of evil by showing that the existing world is consistent with an omnipotent and perfectly benevolent God. He did so in two ways:
1) Leibniz points out that an omnipotent God will be concerned with creating an actual world, not an imaginary one. The actual world is governed by physical and mathematical laws. Those laws set boundaries as to what is possible and what is not, within the world system that we have. This is not to say that God is subject to or limited by those laws, only that this created world is so subject. To picture a world that violated those laws would be to project an imaginary world. So, when someone throws a rock from a bridge causing a tragic accident, we lament that as an evil. God, being all-powerful, could suspend the law of gravity and prevent the accident. But to do so would be to create a different world than this one - one in which the law of gravity did not always apply. Leibniz described the world as an infinite nexus (network) of interacting parts and principles. If God were to undo any of those parts, the existing world would no longer be. Thus to project upon God the motive to prevent evil is to appeal to an imaginary world, not the actual one. This actual, existing world works as it does because it is the best possible arrangement of parts. Our world is the best possible world.
2) One may object (and many have) that representing this world as the best possible world is ridiculous given all of the senseless evil that exists in it. Leibniz anticipated this objection by pointing out that people assume that the world was made for them, so that God would naturally seek to maximize the benefit and happiness for humans. The is no reason to think that the world is made for human happiness. On the contrary, human beings have such a limited viewpoint (largely centered around self-interest and self-preservation) that it is unlikely that we shall be able to judge the ultimate value of any event. We tend to presume that a world is only good if each part is good, taken by itself. Yet, we can all think of instances in which what was regarded as a negative at one point turns out to be a positive from a larger perspective.
Leibniz's view that ours is the best of all possible worlds has been vigorously debated. Voltaire (1694 - 1778) parodied Leibniz's solution in his famous play Candide. Still, the problem of evil continues to rage and Leibniz's contribution to the conversation retains value.