Jonathan Haidt gave a talk at the Center for Compassion and Altruism Research and Education at Stanford University. It is available on video, here. From that video I personally typed a verbatim transcript of that talk.  This is an excerpt from it:

Elapsed time on video: 1:03:48

The unconstrained vision, I believe, has the worst track record in the history of ideas. This is a terrible and really dangerous idea, quite frankly. Um, in the French Revolution I’ve been stunned to read this, for the book that I’m writing, to read on the French Revolution. My beef with them is that they’re rationalists, they think that reason is a reliable way to find truth, it’s great in the natural sciences, but once you care about something, if you have passions, if it’s a moral issue, reasoning is the slave of the, uh, is the servant of the, wait what is it, David Hume said that “Reasoning is the slave of the passions and can pretend to no other office but to serve and obey them.”I think Hume was right. So I’m really concerned about rationalists, but what I discovered is that in one of the few places on earth where the rationalists got control of an entire country and were able to do with it what they wanted, they created a cult of reason, they banned the clergy, they killed the nobles, ah, and what we had wasn’t oh, let’s get rid of ah, let’s get rid of nations and religion and then people will be one, no what they had was most people didn’t, or a lot of people didn’t want to go along with the revolution, and of course they’re wrong because we know we’re right we have reason on our side, they called themselves the party of reason, also the party of humanity, the French Revolutionaries ended up murdering hundreds of thousands of people. They committed a genocide in the Vendee region lining people against the walls and shooting them, putting them out into boats and sinking the boats. The French Revolutionaries committed genocide. They committed, they would round people, anybody who was accused of anything, rounded up, pronounced guilty, guillotined. We don’t usually say, “Well yeah they committed genocide but other than that oh the French Revolution was great.”So the French Revolution was based on the ex, the most extreme unconstrained view, the philosophes, Condorcet, Sam Harris (gesture, admitting the joke), people like that.

Um, other research, on 19th century communes. Richard Sosis, anthropologist compared, he found the records of communes in the 19th century. Many were organized, were socialist communes based on equality and openness, many were religious communes. And he looked to see how long did they last. Answer, the religious ones tended to last two to three times longer than the liberal, than the secular ones. Because, if you bind people in, you, it turns out the active ingredient was demanding sacrifice. Making them change their names, wear funny clothes, cut all contact with the outside, give up certain foods. If you ask for sacrifice, if you constrain people, they form a community of trust, and they don’t cheat each other.

And if you say, “Welcome everyone. Constraints are bad.“ It quickly decays into a moral, into moral chaos. Again, the unconstrained vision, when it gets a chance to run things, screws it up.

Twentieth century communism, fascism, any any movement that tried to create a new man ends up committing atrocities, ends up committing mass murder. Um, if any, if there are any historians here, but as far as I understand it most left wing revolutions have ended with mass murder, because, you have this utopia, people don’t go along, because you got human nature incorrectly, they don’t go along, but you know you’re right because you have reason on your side, so you use force, and you use more force, and you use more force, and you end up like Cuba, or North Korea, or the other communist revolutions. It doesn’t work.

The unconstrained vision in the sciences and social sciences has denied that there’s human nature. They’re just wrong about that, it’s a really terrible idea scientifically. They’ve denied evolutionary psych. Evolutionary psych has some problems which I think are being fixed, but the idea that our behavior is not influenced by evolutionary history is bizarre.