This is a linkpost for https://dyno-might.github.io/2020/09/29/doing-discourse-better-stuff-i-wish-i-knew/
Beware mixing up different kinds and purposes of communication. Your friend's LOLOLOLOLOL is understating the complexity by a long way.
For two-person conversations, where both (claim to be) seeking truth rather than signaling dominance or quality, and where both are reasonably intelligent and share a lot of cultural background, and where there's time and willingness to invest in the topic, https://www.lesswrong.com/tag/double-crux is an awesome technique. Very often you won't resolve the answer, but you'll identify the un-resolvable differences in model or weight of utility you each have. And you'll be able to (if you're lucky) identify portions of the topic where you can actually change your beliefs (and your partner may change some beliefs as well, but it's important for this not to be a goal or a contest - it doesn't matter who started out more wrong, if you can jointly be less wrong).
Where these conditions do not hold (more than two people, some participants less committed to truth-seeking, no face-to-face communication to help reinforce the purpose of this part of the relationship, not everyone with similar background models or capability of understanding the same level of discussion, etc.), the mix between truth-seeking and signaling changes, and there is a tipping point at which truth-seeking becomes obscured. Your failure mode list is not sufficient, even if we had working counters to them - there are unique modes for every site, and they blend together in different ways over time. To paraphrase Tolstoy: great communities are all alike, bad communities fail each in it's own way.
I recommend you also include temporal value in your analysis of success or failure of a site/community/forum. Even if the things you list do succumb to death spirals, they were insanely valuable successes for a number of years, and much of that value remains long after they stop generating very much good new discussion.
Totally agree that the different failure modes are in reality interrelated and dependent. In fact, one ("necessary despot") is a consequence of trying to counter some of the others. I do feel that there's enough similarity between some of the failure modes at different sites that's it's worth trying to name them. The temporal dimension is also an interesting point. I actually went back and looked at some of the comments on Marginal Revolution posts years ago. They are pretty terrible today, but years ago they were quite good.
Logic and reason indicate the robustness of a claim, but you can have lots of robust, mutually-contradictory claims. A robust claim is one that contradicts neither itself nor other claims it associates with. The other half is how well it resonates with people. Resonance indicates how attractive a claim is through authority, consensus, scarcity, poetry, or whatever else.
Survive and spread through robustness and resonance. That's what a strong claim does. You can state that you'll only let a claim spread into your mind if it's true, but the fact that it's so common for two such people to hold contradictory claims indicates that their real metric is much weaker than truth. I'll posit that the real metric in such scenarios is robustness.
Not all disagreements will separate cleanly into true/false categorizations. Godel proved that one.
Sometimes people have useful ideas, but give them in a long, boring, hard to read form. Can we allow users to edit each others' content?
You need a lot of shared agreement for that working well. Wikipedia technically allows users to edit each others content in discussions but has strong social norms against doing so for reasons of someone expressing themselves in a way that's too long. On the other hand StackOverflow does allow for editing of questions and answers.
When it comes to a forum like this, it's important to incentivise people who write posts. Part of the incentive is that people control the posts they write to say what they want to say. A system that works like Google Docs where the author can choose to accept or deny requests for change would likely work better.
These ideas are all probably terrible. I'm just trying to say that there's a lot of possibilities, and some of them are surely good.
I thought those ideas were good. (A design might not serve the intended purpose, but it might have other benefits/work well doing something else.)
journal publications. For all their imperfections, these have done a decent job of uncovering truth for several hundred years. What lessons do these offer?
It might be good to look at the other systems around that, that might have also led to progress. (Correspondence, coworkers, collaboration, Conferences, not to mention education (by others or by self), just to name a few.
There is also the universal Girardian mimetic failure mode. It is a spiral of ever increasing desire for things and status, where we want things because someone other wants it. I once wrote an essay on that in the context of internet discussions: https://blog.p2pfoundation.net/online-conflict-in-the-light-of-mimetic-theory/2009/11/25
Another failure mode: the replication crisis in science - where only new and surprising theses are being published, but there is no mechanism for reinforcing existing theories. This also happens in social media - people always want to learn new things. And probably more generally all the other things from https://www.gwern.net/Littlewood
Nick and Maria want to talk about sugar. Does it reduce lifespan? They disagree, but are honest and principled. They want to find the truth and agree on it.