This is definitely one of the most difficult aspects, and already something that we've had some good discussions about on Tildes. There are some people involved already that have been moderators of some of the really divisive subreddits, and I've also had a lot of conversations over the last year with mods from subreddits that work very hard to promote civil discussions even on controversial topics - places like /r/ChangeMyView and /r/AskHistorians.
In terms of pure mechanisms, there are a few things. Tildes doesn't have any downvoting, so that alone takes a lot of the "conflict" out of interactions. Also, for the foreseeable future, new groups won't be user-created, so this means that people can't create very "extreme" little sub-groups (on either side) that treat each other like enemies. We've also been talking a lot about a sort of trust/reputation system (https://docs.tildes.net/mechanics-future), which will make it so that if people get banned for being an asshole, they can't just create a new account and immediately carry on doing the same thing.
In terms of pure mechanisms, there are a few things. Tildes doesn't have any downvoting, so that alone takes a lot of the "conflict" out of interactions. Also, for the foreseeable future, new groups won't be user-created, so this means that people can't create very "extreme" little sub-groups (on either side) that treat each other like enemies. We've also been talking a lot about a sort of trust/reputation system (https://docs.tildes.net/mechanics-future), which will make it so that if people get banned for being an asshole, they can't just create a new account and immediately carry on doing the same thing.