The Bayesian Conspiracy podcast hosted by Eneasz Brodski (the HPMOR radiodrama guy) and Steven Zuber (from We Want MoR) has a Discord. By virtue of being smaller, it is easier to keep up with and imo easier to have conversations in.
There's the SlateStarCodex subreddit and a politics spinoff or something called The Motte
The LessWrong Community Weekend has a Telegram group, mostly for information about the next LWCW.
I'm in quite a few rationalist discussion groups. Once in awhile people in various groups express surprise that other groups exist, followed by the question how they could have possibly known these groups exist.
So I tried to search for a list of rationalist discussion groups online. With 1 minute of effort I found exactly nothing. So maybe the list exists but it's "hard" to find for anyone who wants to dip in their toes without doing deeper searches.
I can solve that problem!
Here is my list.
It is very short. Much shorter than I expected.
The List
That's all?
I'm not sure. I didn't include adjacent or subcommunities like the prediction market chats or the rational ficiton communities. People can go there directly if that is their vibe. These are the only public rationality chat groups I know online.
Did I miss any? Please add them in the comments. Thanks! <3