Has anyone ever tried to create a forum for rational political discussion and achieved:
- At least some level of popularity or usage
- A diverse set of opinions. For example not dominated by either liberal or conservative views.
Is it theoretically possible?
It is theoretically possible, but you would need to take an incredibly hard line about certain kinds of behaviors. Politics tends to actively encourage taking sides (pick your party, pick your candidate, etc), so this would likely remain an uphill battle for all eternity. But there is a lot to be gained by fostering genuinely civil discourse between people with very different views and backgrounds.
I have a long history of promoting the ability for people to share diverse views in online discussion. So, I know how that happens and how to make it happen. I don't do as much of that as I used to, because it makes me a target, benefits other people and seems to mostly bite me in the ass. So, based on personal experience, I will say it can be done, but it is incredibly hard.