Gottfried Liebniz has three claims to fame. First, he was an outstanding mathematician who developed the mathematics of differential calculus independently at about the same time as Newton did. Second, he was a noted philosopher. And third, he was ridiculed by Voltaire in his play Candide [later made into an opera by Leonard Bernstein]. Not by name, of course, but the character Dr. Pangloss is always proclaiming that those in the play “live in the best of all possible worlds,” even as he and Candide suffer disaster after disaster.
In his philosophy, Leibniz asserted [and I’ve simplified the steps] that because God is perfect, and made the world, we must live in the best of all possible worlds. Obviously, many people, including Voltaire, have disputed this, particularly those who have suffered disasters clearly not of their own making.
Even during his own time, many disputed Leibnitz, but from what I’ve been able to discover, most of those disputes were about the logic and structure of Liebnitz’s proposition, rather than the key assumptions underlying the assumptions. Those assumptions, and they are assumptions, because no empirical proof exists to support or, for that matter, to refute any of them are: (1) There is a God; (2) God is perfect; (3) God created the world; (4) a perfect God would not or could not create an imperfect world, or at least not a world representing less than his best efforts. Therefore, we live in the best of all possible worlds.
While many might have liked to dispute those assumptions, in the seventeenth century, publicly disputing any of them was potentially courting a death sentence, or at the least, economic, political, and social ruin.
Voltaire did the best he could to highlight what he thought was the absurdity of the proposition, simply by contrasting the extremes of what happened to people in real life every day, but that observation and others like it had Voltaire in trouble with the religious and secular authorities on and off throughout his life.
But the problem of inaccurate assumptions isn’t just limited to philosophers of past centuries; inaccurate and unfounded assumptions appear to be the bedrock of current politics.