Can you name some social engineering experiments that worked?

Hawthorne effect studied this in college.

The Third Reich

Traffic lights.

Universal healthcare, public housing. public law and order (police), fire departments, libraries. free education. Social Security. Public roads. Public transport. The Post Office. I’m not saying that they have necessarily worked out for every country, but the ones worth living in. Oh, and of course, given what’s going on the US right now, I have to add, The National Park Service. (they rock right now. My dad would be so proud)

Finland is trying one now. They have selected 2,000 unemployed people to give a uniform basic income (UBI), It is too early to tell if the experiment will be successful, but I think it is interesting that they are doing it on a limited basis to test the idea, instead of rejecting the idea outright or risk disastrous results by applying it to everyone.

Oh, I have to add one in for New Zealand. Their Plunket Society was incredibly successful. https://www.plunket.org.nz/what-we-do/who-we-are/our-history/

China’s one child policy was draconian but successfully kept the population low. The demographics of the country are now a bit skewed however with too many older people.