From specific passages in the text of Candide, can you describe Voltaire's vision of human nature?
In particular consider his instance on original sin, the human capacity for violence, the human capacity for reason, and society's potential for reform.
Candide parodies the philosophy of optimism promulgated by Gottfried Wilhelm von Leibnitz that stated that because God created the world, and God is perfect, everthing in the world is perfect. One example of this philosophy, which Voltaire found ridiculous, is in Chapter XXVIII where Candide talks with Pangloss, who personifies Leibnitz's nonsensical reasoning:
"Tell me, my dear Pangloss," said Candide, "when you were hanged dissected, cruelly beaten and forced to row in a galley, did you still think that everything was for the best in this world?"
"I still hold my original opinions," replied Pangloss, "because, after all, I'm a pilosopher, and it wouldn't be proper for me to recant, since Leibniz cannot be wrong, and since preestablished harmony is the most beautiful thing in the world, along with the plenum and subtle matter."
When Cacambo asks him what is human reason, Candide replies in Chapter XIX,
"Alas, it's a mania for insisting that everything is all right when everything is going wrong."
As exemplification of this definition of man's irrational reason, Cacambo and Candide leave Eldorado, the only place where everything is perfect because Candide always wants something else, such as his desire to marry Cunegonde. Ironically, at the narrative's end, even though Cunegonde has become ugly, Candide still desires to marry her, but the barron refuses him saying that his sister will not marry except to a baron of the Empire. Angered, Candide says,
"I've rescued you from the galleys and freed you and your sister; she was wasing dishes here, and she's ugly, and yet when I'm kind enough to offer to make her my wife, you still claim the right to prevent me! I'd kill you again if I listened to my anger!"
"You can kill me again," said the baron, "but you'll never marry my sister while I'm still alive."
In the conclusion, Chapter XXX, Martin decides
that man was born to live in either the convulsions of distress or the lethargy of boredom. Candide did not agree, but he affirmed nothing. Pangloss admitted that he had always suffered horribly, but having once maintained that all was for the best, he still maintained it, without believing it.
According to Voltaire, it seems that without the ability to reason, little ability to reform. After Paquette and Brother Girofee arrive at the farm in abject misery, having squandered their fortunes, quarreled, and been imprisoned, Martin tells Candide that he knew they will spend their money and become worse off than before. Pangloss and the others simply "philosophize more than ever."