The only place people are “intellectually mature” or fair is during structured debates where other people are judging them.
Or if they’re in a close relationship I suppose. And even then it’s going to be hard.
It doesn’t exist outside of that because people rarely have any motivation to be either intellectual or fair. Do you know what a Pyrrhic victory is? If someone is actually actively trying to be intellectual, they are probably not mature. It’s almost like an oxymoron.