John Rawls' "Veil of Ignorance" is still one of the most intriguing though experiments to me:

"Suppose that you and a group of people had to decide on the principles that would establish a new society.

However, none of you know anything about who you will be in that society. Elements such as your race, income level, sex, gender, religion, and personal preferences are all unknown to you.

After you decide on those principles, you will then be turned out into the society you established."