Pushing Back

What happens when Reason shows that we are unreasonable? I think this dilemma represents the higher conflict of the middle enlightenment pretty well.

Voltaire and those intellectuals within the controlling aristocracy (the monarchy and the propertied elite) solved the problem by constructing a paradigm in which civil authority enforced the reasonable behavior of the citizen. But the sacrifice of Liberty was contrary to the highest principles of the cause. A couple of young idealists sought ways to fight back.

Diderot was a country boy, the son of a cutler. Rousseau was the son of a watchmaker; he grew up in the austere climate of Calvinist Geneve. Both were gifted enough to work their way to the highest levels of Enlightenment society, but they never lost their practical affection for the common citizen. Tough living had given them something Voltaire didn't have: a backbone of realism that helped form and support their ideas. Barzun states it like this:

Diderot ranks as the pivotal figure of the century because his
thought evolved, passing from critical effort based on reason to a
conception of man and society in which impulse and instinct are seen as stronger than reason. The pivot for Diderot's gradual turn is the Encyclopdie. It was toward the end of its production that Diderot began to write the masterpieces embodying his doubts and his new inferences.

If men are apt to behave like animals rather than scientists, how do we elevate them and at the same time preserve Liberty? This had become the question of the day. Rousseau's answers would not make the aristocracy happy.