"It follows from the supreme perfection of God, that in creating the universe he has chosen the best possible plan in producing the universe" 

From Principles of Nature and Grace, Based on Reason- Leibniz

A remarkable part of Leibniz's philosophy is his argument that we live in the best of all possible worlds. In his Principles of Nature and Grace, Leibniz tells us that God is infinitely good; therefore, his creation is good in that it represents the greatest excess of good over evil in all the possible worlds that God could have created. It was this belief of Leibniz that was savagely criticized by Voltaire in his novel Candide. Here, Voltaire, through the novel characters and themes, highlights the evil and brutality of the world with [his use of] satire, and wit. Voltaire tells us that life is truly a vale of tears and we only have to look around us and see suffering in every person we meet - a message to Leibniz to go out and look at the world we are in.  

Asking us to accept the world as it is because this world is žthe best of all possible worldsÓ provokes many questions. To accept the world as it is as being the best possible, means accepting the evils in it as well. This raises the immediate questions: did God inject the evils in the world for us to accept them, live with them, and indeed spend our lives thanking Him for creating such a world? If the place and role of humankind as mandated by God is to live only to worship Him and pray till the end of our lives, then evil certainly serves a purpose, in making ŽfaithŪ more meaningful (difficult). Yet, if we were to fully accept the evils of the world as part of žthe best of all possible worldsÓ; then, why struggle to improve things? If our work and labour offer to provide a better life, this implies that the existing world was not really the best possible after all, because it left room for improvements resulting from human efforts. Efforts, for instance, to end wars, or ease natural disasters, or alleviate suffering.

It seems that if humanity were to fully embrace LeibnizŪs notion of this as žthe best possible worldÓ, no medicines would have been created to reduce mortality, and no efforts would be made to avert wars and natural disasters.

Or, on a related theme, consider some political games of our times: particularly the game of claiming someone as being evil in order to give oneself the right to destroy them. Take the example of the U.S. invasion and subsequent occupation of Iraq. Over several decades, as many commentators have observed, the Iraqi president waged a pitiless war against his own people, with the active support of the United States government. Then, all of a sudden we found the US invading Iraq and executing its president claiming the actions as mandated by a struggle between Žgood and evilŪ. Of course, many countries have used such games in order to have the right to destroy or plunder enemies Nonetheless, there remains the fact that we do in practice seek and work for a better world in a world that is not, it seems, the best of all.