Doctor Pangloss is a character in the 1759 satirical novel, Candide, or Optimism by Voltaire. He is modeled on philosophers such as Gottfried Leibniz, who defended an optimistic view of the universe. Pangloss insists that this is the “best of all possible worlds,” resting on circular reasoning, even if the face of absurdly overwhelming evidence. Voltaire was probably making fun of people who used the pretence of reason to defend a religious dogma, like an omnipotent, benevolent deity, which they would never reject anyway. Voltaire's position in other writings was to separate natural science from metaphysics. While in some ways, this kind of separation of fact and belief is characteristic of modern thought, Voltaire also embodies a critical, skeptical approach which is worth remembering when we encounter latter-day conceptions of “modernity.” In 19th century thinking, modernity was a natural evolution of society away from primitive tradition. Voltaire's Enlightenment attack on superstition ironically has led to a dogma of a new kind. Hence the epithet Panglossian is still handy as a label for anybody who asserts that progress, development and modernity are natural.

Voltaire. 2006 [1759]. Candide, or Optimism. Project Gutenberg. http://www.gutenberg.org/files/19942/19942-h/19942-h.htm