These were philosophers who confronted a world of superstition and feudalism and sought to expose it to the clarifying light of reason. Inspired by the scientific revolution, they had great faith in the power of individual reason to detect error and logically arrive at universal truth.

Their great model was Descartes. He aimed to begin human understanding anew. He’d discard the accumulated prejudices of the past and build from the ground up, erecting one logical certainty upon another.

What Descartes was doing for knowledge, others would do for politics: sweep away the old precedents and write new constitutions based on reason. This was the aim of the French Revolution.

But there wasn’t just one Enlightenment, headquartered in France. There was another, headquartered in Scotland and Britain and led by David Hume, Adam Smith and Edmund Burke. As Gertrude Himmelfarb wrote in her 2004 book, “The Roads to Modernity,” if the members of the French Enlightenment focused on the power of reason, members of the British Enlightenment emphasized its limits.

They put more emphasis on our sentiments. People are born with natural desires to be admired and to be worthy of admiration. They are born with moral emotions, a sense of fair play and benevolence. They are also born with darker passions, like self-love and tribalism, which mar rationalist enterprises. We are emotional creatures first and foremost, and politics should not forget that.

These two views of human nature produced different attitudes toward political change, articulated most brilliantly by Thomas Paine and Edmund Burke. Their views are the subject of a superb dissertation by Yuval Levin at the University of Chicago called “The Great Law of Change.”

As Levin shows, Paine believed that societies exist in an “eternal now.” That something has existed for ages tells us nothing about its value. The past is dead and the living should use their powers of analysis to sweep away existing arrangements when necessary, and begin the world anew. He even suggested that laws should expire after 30 years so each new generation could begin again.

Paine saw the American and French Revolutions as models for his sort of radical change. In each country, he felt, the revolutionaries deduced certain universal truths about the rights of man and then designed a new society to fit them.

Burke, a participant in the British Enlightenment, had a different vision of change. He believed that each generation is a small part of a long chain of history. We serve as trustees for the wisdom of the ages and are obliged to pass it down, a little improved, to our descendents. That wisdom fills the gaps in our own reason, as age-old institutions implicitly contain more wisdom than any individual could have.

Burke was horrified at the thought that individuals would use abstract reason to sweep away arrangements that had stood the test of time. He believed in continual reform, but reform is not novelty. You don’t try to change the fundamental substance of an institution. You try to modify from within, keeping the good parts and adjusting the parts that aren’t working.

If you try to re-engineer society on the basis of abstract plans, Burke argued, you’ll end up causing all sorts of fresh difficulties, because the social organism is more complicated than you can possibly know. We could never get things right from scratch.

Burke also supported the American Revolution, but saw it in a different light than Paine. He believed the British Parliament had recklessly trampled upon the ancient liberties the colonists had come to enjoy. The Americans were seeking to preserve what they had.

We Americans have never figured out whether we are children of the French or the British Enlightenment. Was our founding a radical departure or an act of preservation? This was a bone of contention between Jefferson and Hamilton, and it’s a bone of contention today, both between parties and within each one.

Today, if you look around American politics you see self-described conservative radicals who seek to sweep away 100 years of history and return government to its preindustrial role. You see self-confident Democratic technocrats who have tremendous faith in the power of government officials to use reason to control and reorganize complex systems. You see polemicists of the left and right practicing a highly abstract and ideological Jacobin style of politics.

The children of the British Enlightenment are in retreat. Yet there is the stubborn fact of human nature. The Scots were right, and the French were wrong. And out of that truth grows a style of change, a style that emphasizes modesty, gradualism and balance.