[oldsj]

I think there's something to this and have been thinking about this for a while too. Just today tried to see if diff.me was available, sadly it's not.

I was thinking something like a git repo with a flat file in it. You list your beliefs / opinions / things you think are facts in a structured way (maybe a tree like structure) going all the way back to some "root". Then you can easily diff this file with someone else and see where you agree and differ. Changing someone's mind could just be a pull request :)